Welcome to Introduction to programming. My name
is Steven in my name is Shawn. Over the next 90 minutes, we'll be taking you through this series
consisting of 21 different segments that hope to cover the basics of computer programming, which
can apply to any and all programming languages you might want to learn. We'll be starting with the
simplest question of what is programming. And from there, we will be working our way up as we talk
about common features of computer science such as loops and arrays, we'll discuss how to read
and write code, debug code that you've written some strategies to help you plan out your code
and much, much more. The complete list of topics that are going to be covered in this lecture style
video are shown on the screen. Now, additionally, there will be timestamps in the description,
so feel free to skip around. If you're already proficient in some areas of computer science, or
just want to know about a specific topic we will be covering. Hopefully, by the end of the series,
you'll have a basic understanding of what computer science is, along with an armory of useful skills
that will help you unravel whichever programming language you decide to learn. First, we'll only
be covering the major key points that apply to all programming languages. So we'll be shying
away from topics such as object oriented coding, and command line navigation, as those are things
which are language specific. Additionally, there will be no software required for you to download
in order to follow along with this tutorial, as we won't be writing any code in an ID to
keep things simple and concentrated. This video is meant for those who are interested in computer
science and programming but have no idea where to start and have little to no background information
on coding. And so if that sounds like you, then strap in, as Shawn and I work our way
through the wacky world of computer science, starting with the biggest question probably on
your mind, which is what even is programming? Well, the dictionary defines it as the process of
preparing an instructional program for a device. But that's a really confusing definition. So
in layman's terms, what exactly does that mean? Essentially, it is attempting to get a computer to
complete a specific task without making mistakes. Imagine this for example, you want your less
than intelligent friend to build a Lego set, except he has lost the instructions and can only
build based on your commands. Remember, though, your friend is far from competent. And so if they
are not given very specific instructions on how to build the set, there are many mistakes that they
could make. If he thinks like a computer, then if there's even one piece that you have not told him
specifically where to place and how to place it, the entire Lego set will be ruined, and you will
be left to suffer a complete mental breakdown, causing the whole goal of the project to be
corrupted. giving instructions to your friend is very similar to how programmers code. Instead
of a less than intelligent friend, you have a less than intelligent computer. And instead
of instructions on how to build a Lego set, we are feeding information on how to complete a
program like a game or a web application. And an important thing to note is that computers are
actually very dumb. We built them up to be this super sophisticated piece of technology, when in
actuality, a computer's main functionality comes from how we manipulate it to serve our needs.
Now, programming isn't as simple as giving your friend instructions. Since in a programmers case,
the computer doesn't speak the same language as you. The computer only understands machine
code, which is a numerical language known as binary that is designed so that the computer can
quickly read it and carry out instructions. Every instruction fed to the computer is converted into
a string of ones and zeros and then interpreted by the computer to carry out a task. Going back to
the Lego example, this process wouldn't be like if he was not only less than intelligent. But
to make matters worse, he could not understand English and only speaks in Mandarin Chinese.
In order to speak with him, you have to convert the instructions that you understand in English
into the language that your friend understand. This process is essentially what you must do for
your computer in order to make it understand the instructions that you give. The big difference
between the two examples, however, is that it is very difficult for people to understand machine
code in binary. Directly translating what you want the computer to do into machine code is
extremely difficult, in fact, almost impossible, and will take a very long time to do it if you
could. Each program is composed of millions upon millions of those ones and zeros. So how exactly
are we supposed to translate our instructions into machine code. This is where programming
languages come into play. programming languages are fundamentally a middleman for translating a
program into machine code. These languages are much easier for humans to learn than machine code,
and thus are very useful for programmers. Going back to our Lego example, a programming language
would sort of be like an interpreter that's able to take the instructions you give them in English
and translate them into instructions your non English speaking friend can understand. This makes
programming languages extremely useful and the backbone of any good program. Think of programming
languages as not English and not machine code, but somewhere in the middle. There are many different
programming languages out there that each have their own unique uses. languages such as Python
and Java, are just general purpose languages that can perform a variety of computational tasks, or
robots C or HTML or CSS, or languages designed for more specific purposes, such as moving a robot
or constructing a website. languages can also vary and how powerful they are. For instance,
JavaScript is a scripting language that is designed for smaller tasks, or Java or Python
can carry out much more computationally taxing processes. We can measure a programming languages
power, or level by how similar it is to machine code, the series of zeros and ones we talked
about earlier. low level programming languages, such as assembly, or C, are closer to binary than
a high level programming language, such as Java or Python. The basic idea is that the lower the level
of your programming language, the more your code will resemble what the machine can interpret as
instructions. Aside from the different purposes that each language fulfills, choosing a language
typically comes down to a matter of preference, as are usually many languages that can accomplish
similar tasks. Try different languages, and decide which ones rules interface and
level of simplification you like best? So now that we know what programming is, how do we
actually write code? It sounds like we can simply type words into a text document and automatically
assume that the computer can translate it into machine code, read it and carry out a task
like opening up a browser. And additionally, we can't just write down rubbish in certain
programming languages mentioned in the previous segment, and expect the computer to understand.
So how are we supposed to write code then? Well, the answer is with an ID. And ID, which stands
for integrated development environment allows the facilitation of code by a computer. It is provide
a graphic interface on your computer in which the programmer can easily write, run and debug code
without having to worry about problems with complication or interpretation of the program.
Think of an ID is any other program on your computer, such as a game browser, or even the file
explorer, except we'll be using it to write code, IDs are able to turn your code into machine
code and run it through the computer to produce results. In addition to providing a place for
programmers to develop their code IDs provide some extremely useful tools for programmers
to ease the job of writing code, such as built in error checking, because as we'll talk about
later, code doesn't always run correctly. Auto filling for frequently used words or phrases, and
a project hierarchy, which will help you organize and manipulate the files within your project.
Back in the olden days before IDs code used to be written on punch cards and then fed into
computers, which would take hours and cause a lot of pain. IDs nowadays act as sort of a fast
track to writing code and make things a whole lot easier for programmers. An example of a specific
ID can be seen on your screen now. In the center, you can see the program that is currently being
written. And right below it is the console, which can print out useful information for the
programmer. This specific ID is used to write Java code. IDs are extremely powerful and will be
used in almost 100% of your programming projects. So through these IDs, we are finally able to write
and compile code smoothly without worrying about the computer not being able to understand it.
The next problem we run into then becomes how do we write this code in the ID. Because it's not
like we can just type random words from a certain programming language and expect the computer to
understand this is where a programming languages syntax comes into play. Now, just as if you were
learning a real language, learning a computer language can be very similar. Some have different
styles that may seem odd. Some may make you use weird or abstract concepts which may be confusing.
And like all languages, programming languages have a set of rules that you must follow when writing
code in that language. And at the forefront of those rules is grammar. Programming grammar is
referred to as syntax and is very similar to real world grammar. Each programming language has
its own syntax or rules that you have to follow to a tee if you want your program to run correctly,
just as if you were speaking in real life. These can be things such as how you type out certain
functions, what you put at the end of the line of code, and how you set up certain functions. Each
language is unique in its syntax, and while some may share similar rules, all will have some quirk
which makes it stand out from the rest. syntax is something that catches a lot of people off guard
since many expect every programming language to follow the same set of rules. But as we spoke
about in the last segment, because each language is specialized for a specific task, each needs
its own set of rules to function. Breaking or disregarding these rules will result in an error.
Just how breaking or disregarding rules in real life will result in an unintended message. As an
example, if you wanted to do something simple, such as initialize a variable, which is something
that we haven't covered yet, but the example is still relevant. In Java, you'll notice how we have
to specify what type of variable we're defining, in this case an integer and also add a
semi colon after the statement. In Python, we don't even need to define that we are trying
to create a variable and just have to type what we want to create. And in JavaScript, we
just specify that we are making a variable, but we don't include what type of variable we want
to make like in Java. Even in this simple example, you can see how much a syntax matters when
learning a new language. Since while the goal of our program remained the same, which
was to define an integer with the value three, all the programming languages shown took different
approaches. All these languages require that you follow this syntax because remember, computers
are extremely dumb. If you forget one semi colon or misplace a character, the entire program
will not run and send you back a syntax error, which is something we'll talk about later. Think
of this as if you forget a comma in a sentence and the entire context of what you're trying to say
gets misinterpreted. For example, in the sentence, let's eat grandma. If you were to forget that
comma. While it may seem like a small mistake, it changes the entire context of the sentence,
making it sound like you're going to eat your grandma. The same rules follow for programming.
If you forget a semi colon, the entire context of your program can be corrupted and misinterpreted
by the ID. Now another thing which makes it so useful is that they will let you know if and
when there are syntax errors in your code. syntax errors, of course, being parts of your code, which
do not follow the same rules where we talked about previously, the ID will tell you where in your
code the errors, and also won't let you run your program until the error has been fixed. Because
of how important syntax is to writing code and learning a new language. It's recommended that
you learn the rules and syntax of a language before beginning to write complex programs in
that language. Most of the rules are tedious to learn but easy to master. And as soon as you
can do that, you'll be able to easily identify syntax errors and take care of them easily and
be writing code in no time. That covers the basic gist of syntax and programming rules. So now that
we know how to write code and where to write code, we next need to cover what happens after we
have typed out our program and run our code. Because writing a piece of code for a game or for
a database is cool and all. But after the computer interprets the program, how will we know what's
happening and whether or not is working? Well, programmers do this by looking at the console. The
console is a text interface within your computer that us programmers can use for a variety
of different purposes. If you remember, a short while ago, we heard a picture of a basic
ID. And one of the main parts of the picture was the console. The main use of the console is to
output text from the program. This is usually done by using a print statement. A print statement is a
command that does exactly what it sounds like. It prints text to the console. The print statement
is the first piece of actual code we've talked about in this series. And it's about as simple
as the print statement. Despite its simplicity is one of the most important functions in
programming and exists in some form in just about every programming language. The most basic
thing you can ask the print statement to do is to just simply make it Say something. This
is done by instructing the console to print, and then include wherever you want to be printed
inside the parentheses. For example, in Python, the segment of code print hello world will cause
a message reading HelloWorld to appear onto the console. Pretty neat. The print statement is also
vital for viewing interpreting the computer's output from program. For instance, if you could
tell a computer to run a simple calculation. For example, to determine what four plus three is,
they will run the program internally and compute an answer. However, what is the purpose of having
the computer run this program if you will not be able to tell what the result is, instead of simply
telling the computer to perform this calculation, instruct the computer to print the
output of the program to the console, and upon the program's completion, seven
will appear on the console. As you can see, the console allows us to easily print information
out to the developer for a variety of uses. It is important to note that the print statement varies
depending on the programming language being used. For example, in Java, there are multiple versions
of the print statement depending upon whether you would like a line break after the printed text
or not, as well as specialized print statements which make your code run more efficiently. Also,
the general syntax of using a print statement and certain nuances of its function contains between
languages. However, you can generally rely on it to carry out the same overall function as it
is a foundational statement for programming in general. All of its functionality makes a print
statement along with the console and very useful developer tool. However, it is important to
remember that that is all it is the developer tool. The console is not really meant to be viewed
by the end user of your program. It tends to be hidden away behind the scenes and other methods of
displaying information, such as displaying text, graphics, or images are used to convey information
to the user instead, think of it like this. When you're using your phone, you see the console
and none of the programs you use. So while you can use the console to give yourself information
about how your program is performing, don't try to implement it in the final product because it
fundamentally just isn't meant for that. Overall, remember to use the console to its fullest extent
when writing and fixing problems in your programs, as it is a great tool to use to tell how
your program is performing behind the scenes. So now that we know a bunch of information about
programming languages, and how and where to write them, along with the print statement under our
belts, let's go over some intuitive things that the computer can do all by itself without you
having to tell it how To. More specifically, we'll be covering some basic number mathematics
as well as string math. Starting off with basic mathematics, the computer already knows how to
do simple arithmetic. This includes addition, subtraction, multiplication, and division, all of
which are represented by the symbol shown on the screen now, in any ID that you may install, you'll
be able to print out the answer to simple math problems using the print statement. Which may seem
counterintuitive, because why would you use the computer to do math when you have a perfectly good
calculator on your phone. But you have to remember that computers are dumb. And anything we want a
computer to do, we have to build up from scratch. basic arithmetic, while simple helps out in almost
any program you may write. For example, if we wanted to build a basic calculator app, we need to
utilize this functionality in order to correctly display the answer to an arithmetic problem when
our user tries to add, subtract, multiply or divide two numbers. Now in addition to the four
basic math equations, most programming languages include an additional operator known as modulus.
If this is your first time hearing this word, don't worry, since it's not usually taught in math
classes. modulus allows us to get the remainder of a divisional operation. For example, when we take
10 modulus three, we're essentially telling the computer to take 10 divided by three, ignore the
actual answer and just give us the remainder of the operation. In this case, one, since when we
divide 10 by one, the answer is three remainder one. The one in this case is what gets printed
out to the console. If there is no remainder, say in the case that we take 50 modulus two, since
the remainder is zero, the function would return zero if we were to print it out to the console.
This can be extremely useful. In many cases, the most obvious being if we want to determine
whether or not a certain integer is even or odd. If we take a certain number, modulus two, and it
returns zero, then we know that is even because any number divided by two will always result in a
full answer without a remainder. But if the system returns one, then we know that the integer is
odd, you will find yourself using the basic math operators a lot more than you think. So it's good
to keep them in mind when running your program. Now, not only can our computer work with numbers,
but it can also work with strings. strings, by the way, are just another way to say text. For
example, hello world is a string, the letter A is a string, and anything enclosed by quotation marks
is denoted as a string in programming languages. We'll cover more about strings in a bit when we
talk about variables. But for now, let's continue. We already talked about printing strings to the
console. But let's say we're making a game and we wanted to print out the statement, game over
for was your final score. Now while we could just make a string that says that exact phrase
and print it out to the console, in some cases, it would be more useful to print out the actual
integer value, especially in the case of a game where the score can change each time you play.
Because score definitely isn't always going to be for. Well, we're also able to print out multiple
strings of text and even integers by adding them together in the print statement. This is known as
concatenation. Continuing with our score example, if we wanted to print out the statement gameover
for was your final score, using four as an integer rather than a string. We could do this by
breaking down the statement into two strings and an integer like so. Print game over plus
four plus was your final score. We of course begin with a print statement, which again will be
different across all languages. But in this case, we're using Python. Inside the print statement,
we start off by printing the string game over. Now here comes the important part. From there, we use
a plus sign and add four to the print statement. Just like if you were adding two numbers, then
we can repeat this process with another plus sign for the final string was your final score.
And we're able to print out the entirety of our statement easily. Doing this we can easily
print out multiple different strings and integers together in one print statement. We could
also combine the two lessons we've learned thus far and do something such as game over plus four
plus four plus was your final score. In the case, let's say where you have a game which gives you
a base score and then four points for a certain task that you complete it. This demonstration also
displays Another important part of programming, which is that oftentimes to get your program
to be the most efficient, you have to combine aspects of code. Now it's important to note
that the computer will take whatever you put in the parentheses and print it out character for
character. So oftentimes programmers will forget to add a space onto the end of their strings. This
can result in a small mistake in which the string from the previous example would be printed out
as if to say gameover four was your final score, which isn't that appealing when displayed on the
screen to the user. So it's a good practice to always put a space after and before your strings
to make sure this doesn't happen, and your string doesn't end up like that. Another important
thing to note is the difference between four in quotation marks, and four without quotation marks.
Now for in quotation marks is treated as a string, rather than a four without quotation marks, which
is treated as a number. This may not seem like a big deal, but again, computers are dumb. And if
you try to do math with a number in quotation marks, it will return an error. Because the
computer doesn't understand that you're trying to perform the operation on a number and thinks
you're trying to add an integer to a string, which is a big no no in programming when you're
adding numbers. So when you're programming, make sure to make a mental note of whether or not
you want to make something an integer or string, because that type of stuff makes a big difference.
All right, that concludes our segment on the base power of computers. Now Next up, we're going to
be covering one of the most important components of computer science. So make sure you pay
attention because next up we're going to be discussing variables, what they are and how
we use them. First of all, what exactly is a variable? A variable is simply something that
can store information and can be referenced and manipulated. Think of variables like a cardboard
box. cardboard boxes, servers means to store items in them, which can be changed that replaced and
modified variables are like cardboard boxes to store information for the programmer to reference
or manipulate. each variable simply has a type, a name, and a piece of information stored inside
of it. The type and piece of information will be covered next, and the name is simply a name for
the variable. Think of it as writing out a label on the cardboard box in Sharpie. Now there
are many different types of variables that a programmer can use, or right now, we will just
be covering what are called primitive variables, which include integers, Boolean, floats, and
doubles, strings, and characters. We'll start off by talking about an integer. An integer
or int for short, is as simple as it sounds, a variable that can store an integer value.
This includes all whole numbers from negative 2,147,483,648 to 2,147,483,648. Notice how I
said whole numbers, integer values can not and will not hold any decimal values. So keep that in
mind when using variables. Secondly is a Boolean. A Boolean is very primitive variable which can
store a value of either true or false. Boolean variables can only hold these two values, and
are extremely useful for conditional statements, which we will cover soon. The next few types of
variables are floats and doubles. Both of these variable types are floating point data types,
which essentially means that these variables can store numbers with decimal places. Whereas
integers values cannot hold decimal values, floats and doubles can. The main difference
between the two is that a float variable can store numbers of our precision up to 32 bit. All
doubles can store numbers with a precision up to 64 bit. Essentially, a double can store more
decimal places than a float. So it all comes down to how precise you want the variable to be.
Up. Next, we have string variables, which are like the strings we've talked about beforehand, except
store somewhere in a value. String variables can store strings of letters, which are just words and
sentences. Strings are useful for displaying text and storing input information. Strings can also
be concatenated together to form combinations of string variables and pre written strings. This
can be very useful for outputting information in a readable format for the user. For example, imagine
we have a string called name. The code asked for input and storage that string of text and name.
To output this information to the user. Rather than simply displaying their name, you can add the
phrase Your name is and make it into a sentence by concatenating. Your name is plus a name plus a
period. This makes it easier to read your code, while also adding variability to your code, which
always makes things more interesting for the end user. Finally, we have char variables. char
stands for character, and just as a name suggests, they can each hold one character. This is useful
when a programmer wants to read one button press or one character in a string without using a
string variable. a specific example is being a game that is controlled by the keyboard, the
program needs to recognize the character that is pressed and translate that into carrying out some
function. Now strings can also hold one character, but chars can hold more than one character. So
keep that in mind when defining variables. Now, why are variables so useful? Well, being
able to store information in a format that can be easily referenced later is essential
for any good program. Oftentimes, in code, you're going to want to keep track of things such
as a user's name, or score. And so by creating a variable called name or score, you store this
information in the variable and then reference it, add to it or modify it. Also, many times to
program will want to take input from the user, which cannot be pre programmed into the code,
and thus the variables required to store the information. A program may also rely on factors
that will change as the program progresses, in which case a variable is once again required.
Also, taking these variables and manipulating them is quite necessary for carrying out many
of the tasks you want to program to carry out. For instance, multiplying in variables or
concatenating string variables. Overall variables are the backbone of any program, and you'll find
yourself using them often if you want to clean and efficient code. So it's best that you learn what
types of variables you need to use and when. So now that we know all about the different variable
types, and we've talked about them a little bit, we're going to delve further into what happens
when we actually define or create a variable, how we reference them, and how we can
manipulate them for our programs. To start, let's go over what happens when we actually define
a variable. Now when we write a line of code, which initializes a variable, and that code is
executed, the computer essentially creates a little space in memory that stores your variable
name and its contents so that it can be referenced later. Going back to our cardboard box example
from the previous segment. Think of this as if you had your own storage facility, and you make a
new cardboard box labeled name. And inside of it, you put a piece of paper with the word no
pointer exception on it. Now, anytime you want to know the contents of your name box, you
could simply look inside and see that it has the contents no pointer exception. This is what
the computer does, except the storage facility is the memory in your computer. The box is a
variable and the contents of the box or whatever the variable is set to be equal to. Anytime you
want to know the contents of the name variable, you can simply call it and the computer will pull
the information that is stored in that variable, and use it how the user see fits. Another thing
to note really quickly is that you can actually make a variable without putting information inside
of it. This would simply be like if you built up a new cardboard box, gave it a label with a sharpie,
but just didn't put information inside of it. You're simply saving that space in your storage
facility for later. This can be maybe because you want to store information in it later down
the road. Or if you're going to use it to store information given to you by the user, in which
case you can't give it information since you don't know what the user will input. Just to note that
if you try to reference or point to a variable, which does not have any information in it, you'll
get what's known as a null pointer exception, which despite being an amazing name for a YouTube
channel is something you generally want to avoid when programming. Now programming languages allow
us to do some pretty cool things with these boxes that we've created. For example, let's say we
created a second variable called channel name. And instead of setting it equal to no pointer
exception, we instead set it equal to our already created named variable. This doesn't create a
space in memory for this new variable. However, it simply points to the same location of memory we
have already created for the name variable. Going back to our storage facility example, this would
be like instead of creating a whole new box label channel name and storing sheet of paper with the
word no pointer exception on it, we instead simply added another label below the name box, and
titled channel name. Now we have two variables which point to the same contents, that being
the string no pointer exception, we usually do this to save space in our code for things that we
know are going to have the same value. variables can also be updated throughout your code. For
example, let's say you had an age variable, and inside of it was the integer 17. Then you
celebrated a birthday and wanted to update your age, all you would have to do is reference the
variable and set it equal to whatever new integer you want the variable to hold. In this case, 18.
This would be the same as having a box labeled age with a sheet of paper eating 17 inside of it, and
then taking that piece of paper out, erasing 17, replacing it with 18 and then placing it back in
the box. Doing this we are able to easily update the contents of our variables throughout the code
as things dynamically shift. As another example, if you were making an RPG, your character would
likely have stats such as attack, defense manner, etc. As the game progressed, you could
continuously update the variables so that the player could get more powerful, the further along
they went through the game. And you wouldn't have to create new variables, you would simply need
to just keep grabbing that box from your storage facility, erasing and replacing the numbers on
the piece of paper and then continue along with your code. Just keep in mind that these variables
are nothing more than places in memory in which a certain value is stored. So we can easily update
the numbers and their place will remain constant. After the code has run its course the place in
memory is deleted until you run the code again, and the program dedicated space for the variable
again, each time you run the code, you're making new boxes in your storage facility. And at the end
of the code, you destroy them all to make room for the new boxes next time. Another cool thing you
can do with integer float and double variables is add them subtract them, divide them, multiply
them and even modulus them. For example, if you're making a calculator app and you store the first
number, the user entered as number one and the second as number two. You could then multiply
num one and num two together and either print them or store them in a new variable entitled
result. Then each time you run the program, the user could input new numbers into the number
one and number two variables. And they would simply be set to those new integers that the user
inputted and return the result that correspond Through those specific numbers, this allows you
to keep easy track of which numbers are which, and what's going on in your program, which is
extremely useful. Also, while you cannot subtract, multiply, divide or take the modulus of strings,
you are able to add them. Like we said previously, let's say you had a string str one with the
contents Hello, and a string str two with the contents there, you could add str one and str
two to create a string that had the contents Hello there, either storing it in a third
variable or printing it out to the console. The last topic we'll be covering on the topic of
variables is the naming conventions of variables, which will be it may seem odd, but it's extremely
important when trying to read your code. So we'll be covering it now. Now variables have to be one
continuous string. And so if you wanted to make a variable that store the player score, you'd have
to find some way to combine the words player and score. Since you can't have the phrase player
score be the name of a variable. All programmers have their own personal preference when it comes
to naming variables. But the one we'll be using in this lecture is called camelcase, which is
the process of not capitalizing the first word, but capitalizing every word that follows
it. Going back to the player score example, using the camel case method, the variable
would be called player score. This allows us to easily see and identify each word and
becomes really useful for long variable names, like the player score before the final boss.
Whereas if we just type it out without camelcase, it would be really confusing and hard to read.
This will help you out a ton when we start finding bugs in our code and need to quickly scan through
our program to figure out what is wrong and adds to the overall readability of the program.
Other programmers might use different naming conventions like using underscores to separate the
words in a phrase. But for now, and this series, we'll be sticking with camel case. Next,
we'll be moving on to conditional statements, which at their core, are statements that change
the path of our code depending on certain conditions. For the sake of keeping things simple
for this section, where Atlanta will connote that our code will not be following the specific path.
In Greenland's I mean, our code is following the path. The main type of conditional statement
that programmers use is the if statement, and this will show up countless amount of times
in any program you write. It is as simple as it sounds, if some condition is true, and usually
that condition will be enclosed by braces, then carry out the instructions located within the if
statements brackets, else do another thing. Now, brackets are used in most programming languages
to indicate a segment of code which will run it works like this. If the condition in parentheses
is true, then all of the code contained within the brackets will run. And if the condition within
the parentheses is not true, then it will skip over all the statements within the brackets. A
quick note is that while this is the case, with most programming languages, some, like Python,
use columns and whitespace to determine where a piece of code starts and ends. But for the sake of
this series, we'll be using curly braces. Now, the condition within the parentheses can take on 1000s
of different forms, such as if the value of the string variable name is equal to Steven, or if the
player score stored in an int variable is greater than five. The list goes on and on. Each of these
statements is evaluated as a Boolean, which you will remember from when we talked about variables
is either true or false. If the Boolean is true, we run the code inside the curly braces. If it's
not, we pretend everything inside the curly braces never existed, and move on with our code. The
if statement comes with two more additional statements that go with it elsif and eltons.
elsif is a conditional statement used directly after an if statement, and carries out mainly
the same function as an if statement. However, the elsif statement will only be evaluated if the
proceeding F or the preceding elsif statement is bypassed due to its condition being false. So we
will run through it like so. If something is true, we will run the code inside of that statements
curly braces out if that's something is not true. But another statement inside of the parentheses
is true, we would then run that code segment. And if neither of them are true, we would skip both
segments of code and move on in our program. This can be a hard concept to wrap your head around
to so let's do an example. If we had a program that evaluated the if statement, if age is equal
to 10, we then have a statement under that which stated outs if age is equal to 12. Now, if the age
variable was 10, which we can see from the example that it is, then the code immediately following
that conditional statement in the brackets would run. The Ultra statement we made will not even
be tested. Since we know that it is going to be false. And thus the print statement inside of that
conditional statements brackets will be ignored, and the code will move on to the rest of the
program. Now for example, let's say we change the age variable to be 12 instead of 10. Now instead
of the first conditional statement being true, it actually evaluates as false since age is no
longer equal to 10. So what we do now is first skip over the print statement, which prints out
that ages 10 and does not. And then we evaluate the elsif statement, we check if age is equal to
12, which again it is. And so now we run all the code inside of that conditional statement before
finally moving on to the rest of our program. So as a review, we check the initial if statement.
If it's good, then we run all the code within that if statements curly brackets and move on with our
program. If the initial if statement is not true, we then move on to any elsif statements and
evaluate if those conditional statements are true. We can have as many elsif statements as we
want, although this could lead to clutter amongst your code. So we'll talk about some alternatives
later to help us out. Now that takes care of the FL statement. So now we'll move on to the
else statement. The out statement, once again, it comes after an IF or an elsif statement,
and we'll carry out its instructions no matter what. As long as the proceeding statement slash
statements are evaluated as false. If we went back to our previous program, we could add an
elf statement, which would only have the code in his brackets run at the age variable wasn't 10,
or 12. This will catch all cases of the program that didn't fit into our parameters. It's good
practice to always have another statement at the end of your conditional statements to catch any
weird cases that may come up in your program. Now remember back to the fact that we could have
1000s of Elif statements after a while that can get pretty cluttered. And so another very useful
conditional statement helps circumnavigate this problem is a switch statement. A switch statement
is functionally similar to many if and else statements together, you write a switch statement
in the form of switch variable. And then below that you write out how many cases the variable
can be. For instance, if we wrote switch var, and then under read write out five cases that the
variable var could be and then the instructions listed under each case would be carried out
if the var variable it would be equal to that case. Now switch statements are different sets.
Instead of using brackets, they use a column to signify the start of a set of instructions and a
break statement to end them. This is very useful, because you are able to essentially use many if
and else if statements without having to write nearly as much. In switch statements, you just
always have to remember to include default case at the bottom of the expression to denote any and
all cases that don't meet the above requirements. There simply catches all the inputs that don't fit
within the program's main cases. It's very similar to just case the end of an if else chain. Now,
why are these statements so useful? Well, many times programmers want their programs to function
differently depending on different conditions. For instance, a program could function differently
depending on the information that the user inputs, such as allowing user to use a program or not user
program if they are above or below 18 years old, respectively. Or in say, a video game. If the user
experiences above a certain threshold, you might want to give them harder opponents to battle.
Another example could be a program was changing the color scheme depending on the time of day. Or
even more simply, if a user presses a button that is meant to move on to another screen in an app,
the programmer would only want that app to change screens if the user clicks that button. A program
without conditional statements would do the same thing every time, and would be very primitive
compared to one that can change depending on its conditions. So now that we know how to make
and use variables, how to compare them, and what we can do with those comparisons, let's move on to
another foundational concept of computer science. And that is arrays. Now we've already talked about
variables, and how great they are for storing singular bits of information for making our code
more simplistic. But one of the biggest drawbacks that comes with variables is their inability to
hold more than one piece of different information. For example, let's say you're making an app which
allows a user to create a grocery list. Well, there's no real easy way to create lists using
variables. Because it's not like you can have one variable store the names of six or seven different
food items. Remember, we can only put one piece of paper in our cardboard box no more. And besides,
even if you were able to add multiple items to one string variable, you would still have a lot of
trouble doing simple tasks you might want from a list such as searching through it, splitting it
or even deleting items from the list when you're done with them. This is the problem that using
arrays solves for us. An array is as you may have guessed by now, a list, you can have an array
of integers, an array of strings, and even an array of other arrays, which is something we'll
cover in a minute. Programmers use arrays when they want to store a lot of variables containing
information that is all related to each other, such as a grocery list or a high score list in
the game. Think of arrays as a column in Excel or Google Sheets. Here the title at the top and
then below it are a bunch of bits of information, which all relate back to the title. Arrays are
super useful when programmers want to store a lot of information that can be easily searched
through because programmers have developed methods of breaking down and using arrays to find
specific information in arrays full of 1000s of different variables. As an example to show just
how useful arrays are. Let's say you're a startup company that owns an app that has 100,000 users.
Every time a user wants to create a new account, they input the username they want and then your
program will have to check to make sure the account name hasn't already been taken. Doing this
requires you to search through the information of all 100,000 of your users to see if that username
has an account with your service and array would be able to get Pain all of this information
and make it easy to search through and find out if the account name has already been taken
with little to no delay. Now, the single most important thing to note about arrays is how you
reference each element of the array within them. Let's create a basic array called numbers and
inside of it, put the digits one through 10. Now, when we want to refer to each cell in his array,
we would call upon its index. an index is just a fancy way of saying that numbers placed within the
array. Now you would think that the first integer in this array would be the first index, the
second would be the second index and so on. But that's simply not the case. In computer science,
programming languages refer to the first cell as zero with element in the array. This means that
if we were talking about our array of numbers we just made, the number four would actually be
in the third index, five would be in the fourth, and so on. So instead of starting our count from
one, we start from zero. It's extremely weird and confusing, but it's one of those programming
quirks, you're going to have to memorize and commit to memory. If you were to not follow this
nomenclature, and refer to the last element in this array as the 10th, you get what is referred
to as an array out of bounds error, since you're trying to reference the 10th element, but there
is no 10th element, where you're actually trying to do is reference the ninth element. Another
extremely important thing to note about arrays has to do with their size. When you initialize
an array, you can do it in either one of two ways. You can either populate it with the elements
that you want contained in the array right then in there, creating and filling the array at the same
time. Or you can define how many elements you want the array to hold, essentially the array size,
and then populate it with elements later. This is because when we initialize an array, it creates
a space in memory that has a size of exactly what you give it. no more and no less. This is great
for when we want to access elements in the array, because we can do so instantaneously because the
computer knows exactly where in memory the array is stored. But the one downside is that we can't
increase the size of the array later on. All array sizes are final. Think of this like setting up
a bookshelf with books by populating a bookshelf with a certain number of books. And then moving on
and filling the next shelf with different books, we have no way to go back and add books to that
first shelf without shifting everything over. Once we decide how much space to dedicate for an array,
in this case, there's no way to add more space. Once again, because this is extremely important to
remember. This means that once an array has been defined, there is no way to change the size of it.
If you have an array titled names with a size of eight, and you try to add another name to the
array, you will receive an error. So be careful when messing around with array sizes. Of course,
you can always go back to the start of your code, when you initially make the array and allocate
more space to it, increasing its size. If you find out that you need more space to hold items,
but once it's defined, you cannot change its size through conventional methods. Another small thing
I want to touch upon really quickly is that when you initialize an array, you must determine
which type of array it is right then in there, for example, you have to specifically say it
will be an array of strings or integers when defining it. And also you're not allowed to mix
and match. Meaning that you can't have an array full of integers with a few strings and some
doubles thrown into the mix, they all have to be the same type. Now the last thing we're going
to cover on arrays is a little funky. And that is the practice of putting arrays inside of arrays.
If you make an array of arrays is referred to as a 2d or two dimensional array. Think of these as
matrices if you've taken an algebra class before. Now, if you haven't Think back to our Google
Sheets example, but instead of using columns, we would add rows as well. So now each element in
an array would simply just be a string variable or an integer variable. But an entirely new array
with its own set of values and elements. The way we index these is mostly the same, except we would
have two numbers to index instead of one. We start with the row and then the column. So a number
in the positions 02 would be in the first row, three columns down, in this case, the name
Clint a number in the position one one would be two rows down and to columns across, in this
case, the name Chris, you get the idea. Now you can also make three dimensional arrays by putting
an array inside of an array inside of an array, but that's a little above what we're going to
be covering. So I'm going to cut it off there. Next up, we're going to be talking about loops.
So what exactly are loops? Next up, we're going to be talking about loops. So what exactly are
loops? Next up, we're going to be talking about loops. So what exactly are loops? Next up, we're
going to be talking about loops. So what exactly are loops? Next up, we're going to be talking
about loops. So what exactly are loops? Well, as you can probably tell by that statement right
there. A programming loop is a statement that is used to run certain instructions repeatedly. Just
like how the opening statement of this topic was repeated five times. loops are very useful for a
variety of reasons. For instance, imagine you want to print something 15 Sure, you could just copy
and paste the print statement 15 times, but this is really annoying to have to do, it becomes even
more unrealistic when that number goes up to say 100 or so. Now what if instead of rewriting
the same instructions over and over again, you would simply place the print statement inside
of a loop, and it will occur as many times as you would like. Now that's the power of loops. With
loops were able to repeat parts of code multiple times. Now, there are three different types
of loops that we will be discussing today. And first is the for a for loop is very useful
for situations like the one described above, where you would like to carry out a certain set of
instructions numerous times. The syntax for a for loop varies depending on the language, however, it
usually consists of three parts an integer value, a condition which the integer value must meet in
order to exit the loop, and an operation to modify the integer value at the instructions inside the
loop are completed. Each time the for loop runs, the operation you set will be performed on the
integer as long as that integer still needs to condition your set, usually being greater than
or less than a constant value, the for loop will continue to run. Eventually, when the integer has
been modified by either increasing or decreasing it to the point where it no longer meets the
condition, the for loop will terminate and the code will continue to run. For example, let's say
our integer value was I and we set it equal to zero, then we set the conditional statement
as I being less than three. So basically, we're saying that as long as I the variable we
just created is less than three, continue running the instructions contained within the loop.
Finally, we make the operation i plus plus, meaning each time the loop runs, we increase it
by one, and inside of the loop, let's just put a simple print statement. Now let's run through
the for loop, we start with i equals 00 is less than three, so we enter the loop and print out
hello world. Now that the instructions are done, we add one two, I'm making it one moving on. One
is again less than three. So we want to get into the loop and print out hello world. Again, we had
one two, I'm making a two now to is still less than three, so enter the loop again and print out
hello world. Finally, we add one to it once again, and it becomes three. Three is not less than three
though, is equal to three, and so we don't enter the loop and it terminates. Moving on to the next
segment of code. This is a simple example. But you can extrapolate it across programming to fit your
needs. Now when using a for loop, we have to make sure to set up a condition that given the initial
integer value and the operation will at some point not be met to avoid creating an infinite loop
and crashing your program. an infinite loop occurs when you give a for loop a condition which
will always be met given the parameters of the program. And so software crashes. For example, a
for the beginning at 10. And checking if is over less than zero, and then adding one to either the
end of the loop will never terminate since I will suggest increase infinitely. After the for loop is
the very similar for each loop. A for each loop, or a for in a list loop in Python is used for
iterating through arrays or lists. Essentially, the loop will go through each element in the
array and carry out some server instructions for each value. If you would like to read all of
the elements in an array and compare them to some value, or perform some operation on them, a for
each loop is extremely useful. So for example, we could have a for each loop which iterated
across an array and simply printed out the value of each array location. Next up we have the
while loop. A while loop will continually carry out instructions while a conditional statement
given to it is true. This can be as long as a certain variable is true. As long as the numbers
that's another number, or while a value is still equal to another value. For example, while loops
are different than for loops in that the loop is not contained within one statement but stretched
out and will continue to run. As long as this condition is true. Like a for loop, you could make
the condition such that it will eventually return false and exit the loop. However, while loops
will not crash your computer should you create an infinite loop. In fact, it is very common for wild
lips to run infinitely. As for certain programs, you would like the program to continually
be iterated through instead of running once all the way through until you exit out of the
program. When programming a game for instance, a while loop would be used to iterate through your
code, continually refreshing the screen as the game runs. From there you can perform operations
on the screen to make the game playable. Creating infinite while loop could be done by simply using
the syntax, while true, as the condition true will always be evaluated as true. Finally, I'd quickly
like to cover the extension of a while loop the do while loop. Do while loops are very similar
to while loops, except they will carry out their instructions at least once even if the condition
is false. And then we'll carry on like a basic while loop. Essentially, the conditions inside
of the loop will run at least once. And then if the condition is still met, they will run again
and function as a normal while loop would. As you can see loops in there many varieties has some
extremely useful functions. using them, you're able to perform an operation many times in a
row. You can iterate through arrays and lists and overall decrease the clutter of your code. Next
up, we're going to be taking a break from learning about common programming statements and dive into
what happens when the code we write doesn't work. More specifically, we'll be covering the different
types of errors that can occur when you're programming and what causes them. Now when you're
writing code, you have to understand that things aren't always going to go the way you expected
them to. And sometimes the program doesn't always work as you had intended. too. We programmers call
these errors. And while annoying, they're always going to come up in computer science, and so
it's best to learn what they are and how to deal with them. Often referred to as bugs, errors and
scripting languages can be narrowed down to one of three types, syntax errors, runtime errors, and
logic errors, all three of which we'll be covering in today's video. To kick things off, let's talk
about syntax errors. These are usually the easiest of the three to solve, since they are oftentimes
something that can be fixed within seconds. If you remember back to earlier in the video, when we
talked about syntax and programming rules, we said that if you were to break the programming rules or
syntax that would result in an error. Well, that's what syntax errors are parts in your program where
you fail to meet the programming rules, and so the computer doesn't know how to interpret your code.
This can be anything from forgetting a semicolon at the end of a statement in Java, accidentally
defining a variable with two words instead of one, or even just misspelling the word string when
you're trying to define a string variable. Lucky for you guys, these errors are extremely
easy to fix, since you just need to figure out where the error occurred, and what the syntax
rule you broke was. Now thinking back to IDs, we mentioned that IDs are so useful because they
do precisely that. They underline the syntax errors and usually provide helpful hints as to
how to fix them. Think of syntax errors as small misspellings or grammatical errors in an essay
you're writing annoying, yes, but not the most infuriating things. Another useful thing about
it is when it comes to syntax errors is that the program will actually restrict you from running
the code unless all syntax errors are cleared, making them even easier to identify and fix. The
second type of error we will be covering is the runtime error. These errors don't show until you
actually run the code, hence the name runtime error. runtime errors are usually caused by a
statement in your code that seems logically sound, but the computer physically has no way of
computing it in a reasonable amount of time. The most common of these errors is one which
we've already talked about the infinite loop, as a refresher or an example. Think of an infinite
loop like this. Say you set your friend down in front of the TV, put on the office, and told him
he could leave as soon as Michael made it. That's what she said joke. Seems pretty simple, right?
Wrong, because instead of putting in the office, you put in friends on blu ray. Now, Michael,
no inappropriate joke, meaning your friend would be sitting there for the rest of his life.
This is basically what happens with a computer, you give it some condition that it has to complete
before the program can terminate. However, you give it no feasible way to finish that task.
This puts the computer in error mode, and most likely it will crash your program. As the computer
desperately tries to complete the condition you gave it. As a computer example, if we try to have
a program terminate when integer i is no longer greater than 99. But eyes initially 100 and only
ever increases, the loop will never terminate, and the program will crash. To avoid these, you
generally want to think through the flow of your code before running it, especially with loops
to make sure that all of your statements can be completed by the computer. Carefully planning out
your code before you begin writing is an extremely useful practice, and something we'll be covering
towards the later part of this video. The final type of error that we'll be covering is a logic
error. This error is also pretty self explanatory. A logic error occurs when the code runs smoothly
without any runtime or syntax errors. But the result that you get just isn't what you want it.
For example, let's say you had a calculator app, and you want it to instruct a program to add two
numbers, except it multiplied them because you use the multiplication symbol on accident. This leads
to the sum being 36 instead of 13. nothing went wrong with the code syntax or runtime wise, the
code runs just fine. It just doesn't work as you had intended it to. These are often the hardest
types of errors to debug. Since most of the time, you'll have no idea why the code isn't working,
and certainly not any idea of how to fix it. This is why it's a good idea to test your
code incrementally. Don't wait until you've been programming for an hour before testing your
application. We're all to run into a lot of logic errors. Logic errors can be extremely fury ating,
and could cost you a lot of time making them a huge pain. But if you know how to effectively
debug your code, you'll be just fine. Speaking of debugging your code that brings us straight
into our next topic, which is how to debug your program. Now let's say you've written a program,
you think it's ready and you're ready to test. You've been working hard on this and you're just
wanting to see it in action. You run the program and wait for it to run smoothly and efficiently.
Only it doesn't work. you've encountered one of the three errors we've just mentioned. You really
want this code to work but how this is where debugging comes into play. If the code is giving
you an error, the first thing you should do is read the error. Oftentimes for syntax and runtime
errors, the ID will print an error message out to the console. See what line or lines it points to
since those little lines with the occurred, and see if you can understand and fix what the problem
is. If the error isn't clear, or you've never heard of it, then try googling it as there are
many websites out there. So just Stack Overflow, which service forums to ask an answer problems
with code. Chances are, if you've had a problem, someone else has had the same issue and there's
likely a tested solution. Usually, when the syntax or runtime error pops up, you should be able
to find a fix for it fairly easily. However, as I said before, the issue may arise from some
loophole or oversight in the code you hadn't planned for beforehand. Maybe you did something
as simple as multiply two variables instead of adding them. These are logic errors we talked
about previously, these problems usually won't have red text show up to explain what went wrong,
you'll have to figure it out yourself. Now, there are a few different strategies that you can use in
order to track down and fix a logic error. First, you could use print statements and the console
in order to determine where the code is going wrong. Imagine you have a conditional statement
that will run one segment of code if an integer x is greater than five, and it will run another
segment of code if not, if in your program. X is supposed to be greater than five when the program
reached this conditional, but for some reason, the program is still printing out x is small,
you can use a wrench they're meant to help. For this problem. Specifically, you could place
the print statement before the branch or the conditional that would print the value of x. Now
when you run the program, you know exactly what the computer is thinking, printing out the value
of x just before the FL statement. While you know the variable has the value you wanted to have. And
if it doesn't, you know that somewhere above that conditional is something went wrong, and x was set
to a value you didn't want it to. In this case, x is equal to two, which is why x is small is
being printed out. Now that we know what the problem is, we can track down where and when in
the code, we modify x in order to solve it. Use print statements to determine where your program
goes wrong, and then try to track down the cause of these issues and solve them. If you use this
strategy, make sure you end up deleting the print statements afterwards to avoid clutter in the
console. The situation described above could also be solved using a breakpoint. a breakpoint
pauses your program when the line you placed a breakpoint at is reached. If say you would like to
program to run through a certain conditional and set a variable based on that conditional. But you
are unsure if this actually happens in your code, you can place a breakpoint inside the conditional
path that you expect to run. Upon the breakpoint being reached, the program will pause and wait
for you to continue it through a button press. This signals that this button occurred where the
breakpoint was placed. In this case, the correct conditional path has been reached by your program.
You can then continue the program knowing that this was or wasn't where the error in your code
occurred. breakpoints can be used in conjunction with print statements. In order to do both pause
the program and perhaps view the values of your variables at the moment in time to give yourself
all of the information you could want. You can also have multiple breakpoints to help slowly work
your way through your program and determine where an error has occurred. A combination of these two
strategies will help you easily determine where in your code you have incurred a logic error.
Next, let's go over what to do if you think you have tracked down the section of code that causes
the problem. You may think you should delete it, but it's likely you put it there for a reason.
And you don't want to lose all that work if you don't have to. Firstly, try commenting it out.
Comments are used to markup code and explain their surrounding sections. They can also be used to the
bug. Anything that is designated as a comment will not be read by the program as code and will be
skipped over. Essentially, it becomes something that is only there for you, the programmer to
read. The syntax varies from language to language, but it usually involves placing some symbols
before or around the code you would like to be commented, examples of how to comment in different
languages can be seen on the screen now. Also, when you comment something, the ID will grayscale
that line of code, making it extremely easy to determine what's commented and what's not
commenting code deletes it in the computer's eyes without actually deleting it. If a problem is
present before you comment a section of code, but it's gone afterwards, then that section of code is
the culprit. If you comment part of the code out and there are still issues and move on to another
section until you find the culprit. Once you do, you can tweak it until it works as intended
or deleted entirely. And you'll have a fully functioning program once again. Now that we've
talked about what to do if you've encountered an error, and a strategy on how to find and fix it,
I'd like to talk about some strategies you can use to avoid errors in the first place. Firstly,
backup your code frequently. In the event of the code completely bugging out and you being
unable to fix it, you will want the ability to revert to a previous version where the code was
still working. If you save frequently enough, you will probably not lose too much work. Version
managers like GitHub or subversion can help with this as they backup code to an online cloud
service, which you can easily pull previous versions of the program from at any point. Also on
top of saving, running your program frequently to ensure that the current version works as intended.
This accomplishes two things. First of all, it prevents you from saving a backup that
doesn't work second If you encounter a problem, it will be easier to find if you have only
made a small number of changes since the last time you ran it, and it worked. And thus, you
will only have to look through the new code for problems. If you've spent five hours coding
and hadn't run it during that time period, it's going to be likely that at some point,
during that five hour code session, you messed up, and it's going to be even harder to figure out
where you went wrong. errors, while annoying and extremely frustrating, are a fundamental part
of making you a better programmer. Alright, now that we've covered errors for a bit, let's
hop back onto the programming statement train and talk about one of the most important concepts
in computer science, they'll function. Now, you may not know it, but we've actually been talking
about a few functions, this entire series, print statements for loops. And even the basic math
operations we've talked about are all examples of functions, which of course, begs the question
of what actually defines a function? Well, a function is a segment of code that can be easily
run by calling the function name. And depending on the type of function will do something in return.
functions can be called numerous times and in numerous places in your code. Essentially, they're
like wrapping up a segment of code into a nice present, and giving it a name, which, when called,
will unwrap the present and go through the code that you had wrapped up. For example, the print
statements we've been using this series allow us to print something to the console anytime we
want. Those are functions, you see, we just call the print function and enter in what we want to be
printed to the console into the parentheses, and the computer does it for us. Behind the scenes,
there's actually even more complex code that is in charge of taking your text and translating it
to the console to be printed. The developers of almost all programming languages realize that you
don't want to program something that manually has to print something to the console through the use
of complex programming. And so they implemented the print statement to reduce the stress and
complexity of code on the user, abstracting it to the single line of code that is print. All of
that code that is used to print something to the console is wrapped up like a present and given
to us in the form of one line. This is actually the main theme of all functions and the backbone
of any good program. Oftentimes, in your program, there are going to be sections of code which are
repeated and serve the same purpose, or equations, which you want to allow different inputs of. And
so you can use functions in order to condense these down into singular lines of code to save
both time and reduce clutter on your code. As you will see soon functions are extremely
powerful, and will definitely be something you utilize all the time in your computer science
journey. The print statement is just one example of functions in everyday code. There are 1000s
of functions that are available to you through the IDs. However, because we won't always use
all the functions that are available to you in a single program, you have to import these
functions from packages found in the ID E, which is something that we'll be covering later
on. Now, there are four main types of functions in most programming languages. And they are
separated by two defining features, whether or not they take in arguments and whether or not
they return values. Let's start by separating them by whether or not they take arguments. But
first we have to cover what arguments actually are. arguments are essentially variables that we
pass into the function in order to be manipulated, and then either returned back to us printed to
the console or used in another operation. Think of functions with arguments like this. If you walked
up to your local Five Guys, and told them that you wanted to get food without supplying a type of
food, they would probably look at you confused. In order to get the food that you want, you need to
tell them exactly what you want to order so that they can give it to you. In this case, getting
food is the function and what you order in terms of food is being passed in as the argument based
on what you tell them or the argument that you pass into the get food function, they will
do something different. You should also note that the argument can be many different things. It
could be fries, burgers, sodas, really anything on the menu, and such as the case with arguments in
programming. Arguments can be strings, integers, arrays, pretty much anything. As an example of a
function that takes in arguments, let's look at the max function, which takes in two integers as
arguments and returns the maximum number between the two. Now for this function, if you don't
input two numbers or variables for it to compare, it's going to throw you an error. Just like the
five guys employee. He doesn't know what you want to eat Since you didn't provide him with any
arguments. And the computer doesn't know which two numbers you want it to compare and return Since
you didn't provide it with two integers. arguments are a way for programmers to have one function
that can do many different things depending on whichever variables can be passed through
arguments, add variability to programming and can help diversify your code. Think of it like this,
a restaurant that only allows one type of food to be made regardless of what you order isn't going
to be very useful or diversified but We're able to pass in arguments and tell them what food we want,
our experience can be heightened and more options can become available to us, which is exactly what
happens when you start using arguments in your function. Now that we've talked about functions
that take in arguments, let's move on to functions which do not, because functions can also be
created and used without taking arguments in and still be incredibly useful to the programmer.
For example, let's say you're making a text based RPG game, and one of the options you give your
player is the ability to view their stats at various points throughout the game. Now every
time you come upon this option, and they choose the view stats button, you don't have to type out
six different print statements for every statistic they may have, your code would get cluttered and
messy very quickly. Instead, what you could do is you could package the six different print
statements in a simple function called print stats, you don't need to pass in any arguments
into the function, since the function will do the same thing no matter what the statistics on the
player are. Now, every time the user wants to view their stats, you could simply call the print stats
function, and voila, the user stats are printed for them to view. This allows you to save a lot of
time writing code, but also a lot of space, which is extremely important when your programs begin
getting into hundreds and 1000s of lines of code, and you want to easily search through it to maybe
debug. Okay, now that we've separated functions into those that take arguments and those that
do not, let's again, split these up into those that return values and those that do not. Another
thing you have to understand is that when you're making your own functions, which is something
that we'll be covering very soon, you have to choose what your function will return, if anything
at all, functions are able to return values back to the user, whether they be in the form of string
variables, integer variables, or even arrays. Now, the thing to note about returning variables is
that calling the function alone won't do anything, you have to return the value into something or
print it out. As an example, the max function we talked about previously would return an integer
back to the user. But in order to do something with it, we would have to either set a new integer
variable equal to the result of that max function. Or we can print out the result of the function,
which in this case, which is print out the maximum value between the two integers. Using functions
which returned values don't do much on their own, you have to pair it with something in order to
gain the use from it. Let's do another example. Let's say you had created a function which took in
two string variables as arguments and combine that using that fancy string that we talked about
earlier, and then return them as a singular string. This combined string function could then
be used to create new string variables. Since what it returns is basically a string, the variable
would simply be set to whatever is returned from this combined string function. The last type of
function is one that does not return anything. And these are known as void functions. Oftentimes,
these are like the print stack functions that we created earlier. Simply use to condense large
amounts of print statements that appear often in your code. These cannot be set to variables since
they don't return anything, and just get the code that's within them run through. So there you have
it, the four types of functions, ones that taking arguments and return something, ones that take in
arguments and don't return something. ones that don't take in arguments, but still return values,
and ones that take in arguments and don't return anything. Each of these four types of functions
are useful and unique in their own way. And you will probably find yourself using each of them
through your programming journey. So get used to the different types of functions and know how to
make the most of them, as they are all extremely powerful. Finally, I'd like to talk about one of
the major benefits of functions, which is that it makes it super useful to make large changes
to your code without having to go through the entire program. Each function call is essentially
just a copy of that functions original code. And so it's very easy to make changes to that initial
function, and have it translate across your entire code. Let's go back to our print stats function
and say that you wanted to go back and add in a new statistic that the player could level up and
through experience in the game. Without functions, you'd have to go back into your code and find
every instance that you'd printed out the user stats and create another print statement
to display the new statistic. However, if you had created a print stats function like
we did just a while ago, all you would need to do is find out where you define that function and
add in a print statement, which displays the new statistic and you're done. Now every place which
you had previously called the print stats function will now also print the new statistic as well.
You can see just how powerful functions can be if used properly, and we haven't even scratched
the surface yet. Now, up next, we're going to cover how we can import other people's functions
that they've written and use them in our code. Before we get technical, close your eyes and
imagine you're trying to build a house. Sure, you could grow your own trees, chop down your own
wood, make your own tools and nails and build from scratch. But why do that when you can simply go to
your local Home Depot and buy these materials that others have already made ready for you. That's
the main idea behind importing functions into your code. Importing functions allows you to gain
access to libraries of functions that other people have already made for you. This is just as useful
as it sounds. There are so many functions that are super useful for any given program, that it
will take you forever to write them all yourself. Luckily, other people have already done most
of this for you. In each programming language, you were able to use an import statement to import
libraries of functions into your program that you can use as you write it. A library is simply a
collection of functions that all have the same theme, and maybe a math library, a data analysis
library, a library that was translated text, or anything you can think of really, there's such
a variety of libraries for any given language that most functions you require that are not hyper
specific to your program can likely be found at some library. In fact, a good portion of any
programmers job is looking online for packages, which can make his or her job easier, instead of
hand writing functions. Now I can hear you saying, Wow, that's sick. How do I do it? Well, it's quite
simple, an import statement. In most languages, an import statement consists of three parts. The
library you would like to import from the package you would like to import from that library, and
then which class from that package you would like to use. For example, we can load up the Java
library. And from there import the util package, short for utilities. And then from that utilities
package, import the scanner class, a class which allows us to read information from the user. A
package is simply a smaller set of functions and methods to help differentiate between the 1000s
of methods contained in a library, and a class is even more specialized than that. Now, if you don't
know what specific classes you're going to want to pull methods from, you can use a start import all
classes within the package you'd like. However, it can be beneficial to be more specific,
and only import the classes you would like, as it helps with the efficiency of the program in
the long run. For instance, in Python, the syntax to import a library is import followed by the
library name. However, importing an entire library is more computationally taxing than importing
specific functions from a library. Imagine you would only be using the factorial function from
the Python math library, it would be a waste of computing power to import the entire library, and
it would increase the load time for your program. For smaller programs, this isn't a big deal.
But it really starts to add up when dealing with larger projects. Therefore, you would instead use
from math import factorial, or the Java equivalent import java dot math dot factorial, and now have
access to that one math command only. This limits the functions that you can use. However, it saves
programming runtime, if you decide you want to use another function that you hadn't planned for,
you can always go back and import that too. Many times. If you try to use a function from a
common package, and you have not yet imported, the ID, he will prompt you to do so if you're trying
to figure out which libraries you want to import, think of the functions you're going to need in
your program, perform a simple Google search. And you will probably run into a package or library
that already exists in your ID that you can use. And if you can't, there are ways to download and
import additional projects to fit your needs. But what if, after all that you still can't find a
library that contains the function you're looking for? Well, that's a perfect segue into what we're
going to talk about next, which is the basic structure for writing your own functions. So at
this point, we've talked about both what functions are and how we can get some very useful functions
by importing them through packages. But there are definitely going to be moments in your programming
career where you're going to want to make your own functions because you want one to be made
specifically to your program in code. Luckily, making your own functions is extremely simple.
There are just some basic rules that I want to cover. Now we've previously used making functions
as an example. For other topics such as the Player Stats function from a little bit ago, they were
extremely abstract and didn't go into depth into what is needed for an actual function to
operate. So right now, we're going to be covering a skeletal system of everything that needs to
be included in a function in order to get it to work. Now think back to the four different types
of functions that we talked about previously, functions that do and don't return values
and functions that both do and don't take in arguments. For creating your own functions.
We're just going to have to go down the list and talk about how to approach creating each one of
them. Starting with the most basic of the bunch, one which takes in no arguments and returns no
values. Before we start that there are a few small things I want to note about function naming
conventions, the variable naming conventions we talked about previously. also translate over
to function names. So you can't have two word functions, and you can't use special characters
like periods or commas. Generally, you're going to want to follow the same camel case style,
which we talked about in the variables video, which is not capitalizing the first word, but
capitalizing each word after that. Alright, so in general, for making functions, each language
differentiates on how you tell the computer, that it's actually a function. In Java, you have
to define the function scope, which is something you don't really need to know unless you're going
to become more invested in Java. But basically, it tells the computer which parts of the code can use
the function in which type can, for this series, all of our functions that we make are going to
be public. From there, you then determine which type of function it is. So in this case, since
it won't be returning any variables, we'll just put void to signify this type of function will
not be returning anything. Finally, you put the function name after those two identifiers, along
with a set of parentheses after it like so, the parentheses are where your arguments would go, if
you were making a function that took in arguments. But since for our first type of function, we're
not incorporating arguments into this function, let's just leave those blank. All of that
is just for Java, Python, on the other hand, all you have to do is put the word def, short for
define, and then the function name with a set of parentheses. So as you can see, each language is
going to be a little bit different in how you make functions. But the main thing we want to remember
is to always add parentheses. From there, we just have what we want our void function to do within
the confines of the function and close it off, and we're done. In Java, the confines of the loop
would be whatever is contained within the curly braces. And in Python, it would be until you are
no longer indented. At its core, this is the most primitive type of function, we've made. Something
which takes in no arguments and returns no values, quite similar to the print stats function from
early on. Moving on to the next type of function, creating a void function that takes in arguments.
Now this process is going to seem very similar to the previous except for one small adjustment.
Remember the parentheses that I mentioned earlier? Well, we put any variables, we want the user to
pass into the function into these parentheses. And then when we call that specific function,
it will be required to have those variables passed into it. For example, in Java, let's make a
function that takes in two numbers and prints out the product of those numbers. We start with the
public void plus name of function setup again, since we won't be returning any values, and
here comes a new part. Inside the parentheses, you define which type of variables you would like
to pass in as arguments, in this case, an integer and then a name for that variable. This name is
what you will use to refer to the integer that the user passes in. For example, let's just call it
num one. Then if we want to add another argument, we simply add a comma in between the two and
we can make another integer variable num two to hold the second number. We can do this for however
many variables we want to pass into the function. But for now, let's close off the parentheses
and just print out the product of num one and number two, as you can see, we refer to the two
numbers that the user will input into the function has num one and m two, whatever numbers that the
user passes into the function will be converted into num one and m two. Now, whenever we want to
call the multiply numbers function, we just have to make sure that we are putting two numbers
in as arguments. In this case, the number five becomes num one and the number eight becomes num
two. From there, we simply run the code and the number 40 is printed to the console. It's pretty
important to note that you can also mix and match variables when making arguments. So you can have
some function which takes in a car, an integer, and two strings all within one function. The last
thing I want to mention about arguments is that when you call a function, you have to follow the
variables you defined when making the function. So for our multiply numbers function, you couldn't
put in a string and then an int, it has to be two integers, because that's what the computer is
expecting to be passed into the function. So now that we've gone over how to make functions that
don't return variables, we have to cover those that do. And we'll start with ones that don't
take in arguments. Now the main difference between defining functions that return variables and
defining ones that do not is that in some cases, you have to specify that you want this function to
return an integer variable. This is most common in Java, where you would replace void with int to
tell the computer that you want this function to give you something back to you in the form of
an integer. This works the same as if you wanted to return a string care or even in an array.
You simply replace the word after public with whatever variable you want to be returned by that
function. The most important thing to remember about making functions that return variables is
that no matter what path your code takes, it must return a variable no matter What? What does this
mean? Well, let's say you had some string function in a game. And inside of it, there was an if
statement where if the player score was above 10, you returned a congratulatory message. This works
fine if you printed the result of this function, and the player score is above 10. But if the
player score was less than 10, then you don't enter the if statement, and then you don't have
something prepared to be returned to the user. And so the function is going to throw you an
error, you have to have all your paths covered, which may seem simple. But if you're making a
function with a switch statement in it containing high amounts of cases, then this can get out of
hand very quickly. Something I like to do to make sure this doesn't happen is put a return statement
at the bottom of a function with a string or an integer so unique that I'm able to tell that the
code is not running properly and can fix it. Also, usually, an ID will let you know if there's a path
in your code or in a function that does not return a variable when it should. The main point I'm
trying to get across however, is always cover your exits and make sure you have a return statement
prepared for any case the user may throw at you. Another small thing to note is that you can't
return one type of variable if you've already defined the function to return another type. For
example, you can't return a string and an integer function or vice versa. The return statement must
always match the type of function no matter what the final type of function is one that returns
variables and also takes in arguments. And for these, all you need to do is combine what
we've learned from the previous cases. First, you assign your arguments in between the
parentheses making sure that you've also defined what type of variable you want to return, and then
ensure that no matter what path the code takes, that you're always returning that variable type.
That concludes our discussion on functions. As you can probably tell, functions are an extremely vast
subject area, and require a little bit of practice to fully understand, which is why later on in this
series will recommend some websites you can use to practice those more difficult topics. Now, I'd
like to switch gears a little bit and continue our discussion from earlier on arrays. arrays, while
useful aren't the only way to store and manipulate information. In fact, there are a multitude of
different ways to store data in computer science, including linked lists, stacks, queues, maps,
trees, and many others to right now though, I'd like to talk about two cool, wacky and zany
ways to store data that we haven't previously covered, array lists and dictionaries. But before
we get into those, let's get a little review and reinforcement of arrays. As you may remember,
arrays are basically lists of values that are stored together. When you initialize an array, you
give it a size and this size is fixed, you won't be able to increase the size of the array. So when
you make an array of length is final. To access the values in an array, you reference them using
an index for starts at zero. What this means is that the first item of an array is not at position
one, it is that position zero. And its position is commonly referred to as its index location. So to
find the nth item in an array, you would refer to it as index location n minus one. However, as the
size of an array is fixed, you have to be careful to not reference a position that's beyond the
total size of the array, or to append too many items to it. As this will return an error. We also
have what are known as two dimensional arrays, which is an array containing an array and each of
its indexes. Or you could have an array containing arrays containing arrays containing arrays
containing arrays, depending on what you're trying to do. multi dimensional arrays can be useful
in more advanced programs for organizing a wide volume of related values. If that's confusing
at all, just get back to earlier for our full discussion on arrays, the timestamps will be in
the description. Now that we've reviewed arrays, let's go over array lists. Array lists are just
lists in Python can be thought of as a growing array. Earlier, we mentioned how you have to be
careful to set an appropriate size of your array, and to make sure that you only referenced in the
pin values such that you remain within the size. However, with array lists, this isn't a problem.
After you initialize an array list instinctively has a size of 10. What if you append values, such
that the size of the array list goes beyond 10 elements, an array list will grow itself, meaning
that the computer will allocate more memory to the array to increase its total size so that the
new values can be appended. This is quite useful when you don't know the exact number of values
that the array will need to store. Or you want the ability to store more values to your heart's
content. such as when you're making a database with an unknown amount of users that will sign up.
There's a lot more to uncover when regarding array lists. But for this surface level series, that
is all you pretty much need to know. So let's move on to dictionaries. Now when we're talking
about dictionaries, we're not referencing that thick book you probably have lying around your
house, which has 1000s of definitions. In computer science. dictionaries are like arrays in that they
store multiple values. Use, however, their values are stored very differently. Rather than being
referenced by their linear position within the dictionary, each value is tied to another value
that is used to reference it, or its key. Because of this, we need to throw away all conceptions
of dictionaries as a linear way of looking at data. Since in actuality, it is much more fluid
and entertaining. Basically, we say that each position in a dictionary holds a key value pair.
When referencing a value in a dictionary, you will use its unique key, and the dictionary will
tell you the value that it is tied to think of it like this. Each time when item to your dictionary,
your computer creates the handcrafted box to store the data. And also a custom makes a jewel key one
of a kind, no other like in the world. This way, there's only one key that goes to the box
that stores a certain bit of information. Because each key must be unique, we're using
the key in a dictionary, it will result in an error being thrown. Because having two keys
that are exactly the same will confuse the computer as to what box or piece of information
that key leads to. However, you can store the same value in multiple key value pairs since the
keys would all be different. Now, like I said, dictionaries are more fluid, making them easier
to organize and then arrays as everything is set up in a more logical manner. That is to say,
it is easier to find the value you are looking for when you're using keys, rather than simply
referencing their positions. Let me explain what I mean. Imagine you have a dictionary of prices at
a store where the key is the name of the product, and the value is the price of the item. Maybe
apples cost $1 milk costs $2 and bread costs $3. You can see the in the dictionary, each key is the
name of a product, and each value corresponds to the price of each product. So to find the price
of bread, all you need to do is simply call the dictionary using the key bread. This makes it
extremely easy to track values through your code. Since you're working with tangible values rather
than numbers which don't mean anything to you. You can also manipulate dictionaries and money the
same way as you can manipulate arrays and array lists. You can iterate through a dictionary and
perform many operations and comparisons on the values. If you want to find the product with
the highest price for example, you can iterate through the dictionary to find the value that is
highest amongst the grocery store items. arrays, array lists and dictionaries are useful in their
own right, as are the mass amounts of other ways to store data, and each boasts certain advantages
over one another. We already covered the basics of these three. But since there are so many, we
don't have time to go in depth into each and every one of them. And so in order to help you
grasp the basics of storing information, we're now going to talk about one of the most important
functions needed to understand arrays, which are searching algorithms. Now just as there are many
ways to store information in computer science, there are even more ways of searching through
lists. Searching algorithms at their core are ways in which we can look through a list of values
stored in an array, say a patient name list or a high score list and find a particular piece of
data. The goal of a searching algorithm is simply to give the algorithm a string or object you
want it to find and have it return the index of the array that contains that string or object as
fast as possible. Now while this may seem simple, lots of software runs on the backbone of being
able to search through lists extremely quickly, making searching algorithms and in particular,
efficient searching algorithms an important topic to cover. Additionally, this is the main
functionality that arrays are used for. And it's the backbone of many of the methods used within
ArrayList as well as many other storage methods. So knowing them will take you a very long way.
Typically, searching algorithms are used to return the index of a particular data points so that
it can be used, modified or updated or checked on. For example, if you're about to check into
a hospital run on an array system for patients, the staff must search through your name in the
database. And by returning the index of where your name is, they now have a quantifiable number
that they can use to easily check you in, rent out prescriptions schedule you for checkups, update
your personal information, etc. Without having to search through the list for your name every single
time. You may think that there's little difference between searching algorithms since computers
nowadays can perform millions of calculations per second. But when you're a huge multi billion
dollar corporation trying to find a certain data point in a list containing 1000s, or even millions
of data points, small differences in efficiency are going to make or break the user experience.
Even a 1% improvement in efficiency can mean a big differences in the amount of time that a user is
waiting for a simple task. Now before we jump into different types of searching algorithms, we must
discern between the two states that a razor list can be in either sorted or unsorted. A sorted
list of information is characterized by some sort of rankl value, whether that be a patient ID,
credit card number, or even by alphabetical values like usernames or legal names. An unsorted list is
just some random assortment of related information not sorted by any particular order or reason. Some
searching algorithms only work for sorted lists, usually the more efficient ones, and some work
for both sorted and unsorted lists. Although these are usually less efficient if you end up pursuing
computer science further, you'll have to deal with both sorted and unsorted lists. So it's good to
know a common searching practice for both. Another thing to note is that we determine the efficiency
of searching algorithms, based on both the worst case scenario and the average number of items
that must search in order to find the index. We call this big O notation in which each searching
algorithm has an equation which takes in the size of the array as an integer and, and will output a
worst case scenario efficiency value that we can use to compare with other searching algorithms.
We can then also look at how long on average it takes to find an element in a list. Using these
two methods allows us to easily compare how efficient two algorithms are. Alright, now that
we've got some background on searching algorithms, let's hop right into it. The first type of search
we'll be talking about is called a linear search. And Eve honestly probably uses multiple times
throughout your life. Every time you have to search for your name on a list of people, you
probably follow the same pattern, you start at the top check to see if the first name on the list
is yours. If it is great. If not, you move on to the next name on the list until either you find
your name or you don't in which case you leave. A linear search works in the same way, you start
with the first element in the list compared to the value that you're trying to find. And if they're
the same, you found your match and you return the index of that element. And if not, you move on
to the next element in the list until you either find the thing you're searching for, or you run
out of lists to check. Pretty simple, right? This is because linear searches are pretty bad when
it comes to efficiency, especially in the worst case scenario. If the item you're searching for in
the list is the last element, you're going to have to check the entire list of items before you find
the one you're searching for. On average, however, you're going to get it about halfway through the
list. This makes the linear search oven worst case scenario since in the worst possible case, it will
take the entire length of the array or n to find the correct value. But linear search on average
will return the correct index in O of n divided by two. We're halfway through the list. Now while the
linear search is in great, it can work with both sorted and unsorted lists, because of the fact
that it will eventually cover every element in the list. The other search we're going to cover
requires the list to be sorted, which may seem like a drawback, but having a sorted list allows
you to use algorithms that are far more efficient than the linear search. So overall, the linear
search is a good basic searching algorithm for if you have an unsorted list. But if your list is
sorted, there are way more efficient options out there for you, such as the binary search, which
we'll be talking about now. The binary search uses a recursive process to break the data in your list
down into more and more manageable bites. Taking advantage of the fact that it's sorted in order to
find the item you're looking for faster. This one is much harder to wrap your head around. So let's
start with an example. Let's say you have a list of 10 names sorted alphabetically, like shown on
the screen now, and you want it to find your name within that list. in binary search, you would look
for the middle most name, in this case, the one at the fourth index. Just a quick aside, since there
is no true middle since the list is 10 names long, the computer automatically uses the next one
down as the middle value. Now, once you find your middle value, you first check to see if the name
you're searching for at the index you've chosen is the name that you're looking for. If it is you
simply return that index. But 99% of the time it's not going to be including right now. So let's
keep going. If the value at the middle name is not equal to the one you're searching for, you check
to see if the value you're searching for comes before or after the middle index. For example,
if you were looking for the name Brandon, and the value at the middle index was Carl, Brandon
obviously comes before Carl alphabetically. And since we know that the list is sorted, what we
can now do is ignore the entire bottom half of the list and just focus on the top. Since we know that
if Brendon is even in the list, it's going to be in that top half. Now we simply treat the top half
of the list as an entirely new entity and repeat the process over again. Again, we would find the
middle most element of this new list of names and again compared to the name you're trying to find.
If it's the name we're trying to find we return that index, but if not, we compare it to see if it
comes before or after the middle index. Going back to our example. Let's say the middle index of this
new list is AJ. Now we know that Brennan comes after AJ alphabetically. So what we can now do
is ignore the top half of the list. Since we know that if Brennan is in the list, it's not going
to be in the top half of our list. Now we again repeat this process again and again until we find
the name we are looking for. So if For example, the middle index is time is Brenden. And that's
what we're searching for. So finally, we would return the index to in binary search. Eventually,
the index we were compared to our search term will be the same. And once it is we can return the
index and move on. Now if we don't find it, which happens after we have eliminated the entirety
of the list without finding our search term, the algorithm will simply return a null value to
let you know that the item you're searching for cannot be found in the list. The binary search
is way faster and more efficient than a linear search. Since we are drastically cutting down the
amount of elements, we have to look at making the program run faster. In almost 99.9% of cases, in
which your list is sorted, the binary search it's going to return a result faster than the linear
search. So if you have a sorted list, your best option is to go for binary. As for efficiency,
the binary search is O log n for the worst case scenario, which could be confusing if you don't
fully understand logarithms. But all you need to know is that it is way more efficient than the
linear search. Its average scenario is actually also o log n as well, which again, is infinitely
times more efficient than linear cases. Now while there are other types of searching algorithms you
can use, these two are the most common for both unsorted and sorted lists. So we will stop there
for now. Up next, we're going to be covering one of the most confusing and important topics in
computer science recursion. Let's start with the most important question, what exactly does
recursion mean? in programming recursion refers to functions that repeatedly call themselves
meaning that any instructions that occur within a function, one of the instructions will be a call
to that same function you're already in. In the extremely primitive example, on your screen.
Now, you can see we have some function which, in the confines of itself, calls itself, a
recursive function will usually take into account some integer as an argument. And we'll use this to
carry out some instructions, modifying the integer that was entered before calling itself again
with a new integer as its argument. To better understand these functions, let's discuss the
basics of how we go about programming one of them. A really good and easy example of a recursive
function is one which sums up all numbers from one to n. So let's make a recursive function
that does just that. The first thing we need is the actual function. And we're going to make
it an integer function, which takes an integer and as its argument, the reason we do this will be
explained later. But for now, let's move on to the base case. A base case is simply a definite value,
which all recursive statements are the ones that are being repeatedly called as we go through the
function tried to get towards at the beginning of the function, we test the value that was passed
in by the argument against the base case to see if it is satisfied. Usually, these base cases are
some requirements like of n as I described before, which has a certain value or is equal to a
certain value, it is extremely important that the base case is set to some requirement that and
will eventually meet for the same reason that it is important to avoid an infinite loop. We do not
want a Stack Overflow error to occur. For example, if our base case, what's the stop calling the
recursive function when n was greater than 100. And if it is not, we will call the same function
again. But with n minus one. And we started with ns, say 99, we would never reach the base case
and the recursive functional or purely call itself over and over again, subtracting one from n and
hoping that somehow it will eventually be greater than 100 until your computer crashes. Not fun.
So anyways, back to our recursive some example, let's make our base case when n is less than
or equal to one. This way when you start at some positive integer and and subtract from
it until it is less than or equal to one, in which case we can exit the recursive statement.
Cool. Now, if n is not less than or equal to one, what we want to do is return the sum of both n
and then the returning value of our recursive sum method minus one. Why do we add and the function
call? Well, let's actually go through the function as if we were at the computer and see why we start
with a call of recursive sum with n equals three, we know that three is not less than or equal to
one. So now we tried to return a recursive sum of n, which is three and the returning value of
recursive sum within n of two. We don't know what the returning value of recursive sum with an N
of two is. So we have to go through the function again, only this time and is two again, and is not
less than or equal to one. And so this function will go through the lF statement and return to
plus another recursive statement, in this case, the returning value of recursive sum with an
N of one. So once again, we have to go through the recursive sum function to get that value that
will be added to two and then returned and added to three And then returned, hang in there, we're
close now in this function, and is less than or equal to one, and so we return n, which is
one. Now we take that n, which again is one, and that is what gets added to to the previous
function call, and then return. So this would return three. Now, this three is what gets added
to the first function call, which is three, and so it becomes three plus three, which is six. And
finally, after all that time, we get six return from the function, which if you've been following
along at home, three plus two plus one is indeed six. Now this may seem like a waste of time, since
three plus two plus one is not a hard operation. But those of you saying that I asked you to please
give me a sum of all the numbers from one to 3567. Godspeed. Now recursion is a very difficult
concept to wrap your head around. So if you're not 100% comfortable with it at the moment, feel
free to rewatch this section of the video in order to better familiarize yourself with it. Alright,
cool. Now that we have a little background on recursion, let's talk about why it works so well.
Now to understand why and how recursion works, we must first understand what a stack is. A stack
is a data structure that contains all of the tasks you instruct your program to complete. Based on a
certain method, your program will then carry out the tasks you give it is called a stack. Because
if we start another process before the previous one completes, the process is stacked on top
of the other one, such as the animation on your screen is showing now, programs we write will
follow the LIFO structure. For those unfamiliar with accounting LIFO means lastin. First out, or
the last item put on the stack will be the first one removed from it. Essentially, every time you
ask your computer to complete a task, that task is added to the stack, and will be the first one to
be resolved. Think of it like a stack of stones, you can keep adding stones on top of your pile.
But in order to get to the one at the bottom, you must first remove all the rocks on top of
it. Now when your functions continually cause itself without end, without a base case, like in
our infinite loop example, then this stack will never be resolved, as items will be continually
added to the stack without any of them ever been completed. In this case, the memory allocated
to the stack exceeds the maximum allowed and a Stack Overflow error occurs resulting in your
program crashing. Think of this as if you're doing chores. And before you complete one chore, you
get called to do another chore. And then before you can complete that one, you get called to do
another one. Since you keep stacking tasks, or shores on top of one another, the stack of tasks
will never be completed. And you will probably die before ever finishing all of your chores.
This is the same logic that makes infinite loops crash your program. recursion works on these same
principles. The initial call makes a second call, which is added to the stack. And now that one
must be taken care of first. But in that one, another function is called which gets added to
the stack, and so on until you reach the base case and what you slowly start going back down
the stack. In conclusion, recursion in general is extremely useful, because by calling the same
functions repeatedly, it breaks down the problem into smaller sections, and results in the program
being more efficient. small parts of problems are easier to solve and less taxing to compute than
the entire problem at once. And the computer can combine these small solutions into the whole
solution at the end. Now as we wind down our introduction to programming series, we want to
take some time and go over some of the soft skills needed to be successful computer scientists.
Since it's not all about writing code. In fact, many professional computer scientists will tell
you that the majority of their job is spent thinking about code rather than actually writing
it. This is because much of programming boils down to problem solving. How do we optimize the
system? How can we make this feature for our app? What type of movement Do we want for our game?
And how can we program it? The harsh truth is that no good program has ever been written simply
from the programmer, getting the prompter idea, sitting down, hopping on an ID and starting to
write code. There are many tasks we should go through beforehand in order to plan out our code.
So we ensure that when the time comes to program, it's a clean and easy process and not riddled with
mistakes and bugs. This is where pseudocode comes into play. Think of pseudocode like this, if you
wanted to take a family trip to the Grand Canyon, would you simply hop in your car and drive off and
figure out things later? No, because that would be ridiculous. Instead, you would spend some time
planning out the trip. What sites or places do you want to visit? What hotel reservations are you
going to have to make? What kinds of things are you going to do when you get there? What routes
or highways are you going to take and why? All of these things must be determined before you can
even think about hopping in your Ford Explorer. So how does this translate to pseudocode?
Well think of our family trip to the Grand Canyon as a program, programmers use pseudocode
pseudo meaning not real, and code, meaning code as a means to plan out their programs before they
write them. Just like how we planned out our trip before going. They throw away syntax and naming
conventions for variables and just focus on what they want the program to accomplish, and how they
plan on doing that. pseudocode is very similar to constructing an outline for a paper that you're
writing, you write down the main topics of the essay, and plan out your major talking points.
But you don't worry about the nitty gritty details of it all, such as word choice, grammar,
conventions, and proper formatting. By doing this, we allow ourselves to think freely and not worry
about stressing the small stuff, at least not yet. Alright, now that we know what pseudocode is,
let's talk about how we write pseudocode. You see, the best part about pseudocode is that it can
take the form of many different things for many different people. Each computer scientist
has their own methodology for planning out their code. And there are probably hundreds of
different methods of writing pseudocode that are out there today. Today, however, I'd like to
focus on three popular ones that I think you might find to be extremely useful. The first of these
is known as flowcharts. And mainly they can be used to think through the process of a particular
function. a flowchart is fundamentally a graphical representation of a function and how it might
flow. Many programmers do this and lay out the conditional statements and loops that they want
as different blocks in the flow chart connected by arrows and charting out every path of their
function. From there, it's extremely easy to create test cases and follow them through the flow
of the function through the different blocks and arrows. For example, we could have a flow chart
that goes something like this, a user enters in a number, and if the number is eight, I want the
program to return true. However, if the number is not eight, then I want it to return false. It's a
great way to visualize what the functions overall purpose is, and also look for any errors that you
may have missed when thinking about the function, such as a missing path. It also abstracts the
programming statements up to simple blocks, making it easier to modify or change completely.
The best part is that when you have finished testing cases, you can simply convert the blocks
into programming statements, and you have a well written function without any debugging. Another
popular pseudocode technique that is often used is to simply write out what you want your code
to do chronologically. don't necessarily think about what programming statements and functions
you want to use. just jot down from start to finish what it is the program you're writing
is going to do step by step. For example, let's say you're making an app that takes in two
numbers and divides them. The pseudocode for that would look a little something like this. First,
I want to prompt the user to enter a number. And then I want to wait for the user to enter in that
first number. After I get the first number, I want to again prompt the user to input a second number.
Once they do, I complete the operation by defining the two numbers entered and returning the result
back to the user. This all seems like it would be common sense. But remember that oftentimes, we're
not going to be working with simple multiplication or division functions. We may be working with full
scale games, algorithms or user interfaces with many different options. This method allows you
the programmer to not get bogged down with the syntax and conventions that you have to follow,
you're simply making a note of what the program's ultimate goal should be, as if you were explaining
it to a friend of yours. This method really lets you plan out everything that needs to happen in
your program in order for it to run smoothly. It also ensures you don't forget about a piece of
an algorithm or a certain function that you need to write in afterwards. And the final pseudocode
strategy that I'd like to talk about to you today is writing out the main features you want the
user to have when using your program, and what functions or smaller programs, you're going to
need to complete these features. Let's do another example. Say you're making a banking interface.
And on startup, you want the user to initially have two options, they can set up a new account,
or log into an existing account. From there, if they log into their account, then you want
them to have the functionality to withdraw money, deposit money, take out a loan or pay back a
loan. If they decide to set up a new account, you want them to be able to create an account,
store their information in a database, and then access all of the features that are returning
member would have. This may look very similar to the flow chart method. The only difference
being that this is abstracted one level higher over an entire program, rather than just a single
function. If you really wanted to, you could also create a flowchart that would go through the
functionality of all the four methods described above. Setting up a hierarchy like seeing on your
screen now makes it easy and clear to see every function interface you're going to have to make.
This prevents you from having to try to shoehorn a function or feature into an already finished
program at the last second, which is not a very fun experience in the slightest. So There you have
it three pseudocode strategies you can use to plan out your code before you even start writing any
the flowchart method, which is good for thinking through the flow of a certain function. The write
up method, which is good for getting the general idea down for a program, or the functionality
planning method, good for listing out the functions of a certain programs, you can use
all of them, none of them are a mixture of them, or even disregard these and find and create your
own pseudocode methods. The main goal here is to drastically minimize the amount of errors that
occurred during your program and relieve a lot of stress on your head. The importance of pseudocode
cannot be stressed enough. And if you don't believe me, I urge you to try to complete a large
project without it. Okay, so if you've watched the series up until this point, you've gotten a pretty
good understanding of many aspects of programming, and also how to plan out your programs. Now it's
time to go out into the real world and write some actual code. But what kind of program I can hear
you asking me? And the answer is truly whatever you want, really, as I'm sure you know, by now,
you can program just about anything you have on your mind. Anything from simple games to complex
software. This video has equipped you with the basics that are going to need to be used in pretty
much any program you decide to write. But that doesn't mean that every programming language is
perfect for every application. Each language has its own strengths and weaknesses. and choosing the
right one is very important for making it easier, and sometimes just even possible for you to
program what you want. So that's what we're going to be talking about now, choosing the best
language for what you want to accomplish. Now, we talked earlier about low level versus high
level programming languages. In case you forgot, let's do a quick refresher. higher level
programming languages have a higher level of abstraction from machine language, that
series of zeros and ones from way back when, while lower level programming languages have a
low level of abstraction for machine language. For example, block program where you can drag
and drop programming statements together like 2d Legos would be a high level language, as it
does not take a high level of understanding of the inner workings of a computer to programming.
The theoretical highest level of a programming language would be if I could just write down what
I wanted the computer to do in Simple English, and it would just work. But sadly, that doesn't
exist yet. On the other side of the spectrum, the lowest level programming language would be
just feeding zeros and ones into the computer at supersonic speed, which would be almost impossible
and extremely absurd. So how do you choose what type of language is best for your needs?
Well, it depends on what you are trying to do, as sometimes you need very specialized languages
to get done what you want. The world of computer science is vast and contains many fields. So
trying to cover everything in one language would be impossible. This has led to the creation of
hundreds of different programming languages, each designed for a specific task. Right now though,
we'll cover some of the most popular languages and their uses. Now, if you are trying to design a
website, using HTML and CSS is probably your best bet. HTML is a markup language that is designed
for writing the content of a website. While CSS is great for designing the style of the website. you
interact with HTML every day. And you can even see it right now. If you right click and hit Inspect
Element. This will truly show you how complex HTML and CSS can be. Maybe it would be best for you to
use a scripting language. A scripting language is a language that has many commands for you to use.
And that can also be run without needing to be compiled. Scripts can be faster to write in most
programs, and tend to be easier to port between operating systems allowing for cross platform
support. Scripts can also be used with websites, oftentimes adding to the overall user experience
of the site. If you want to go into web design, this might also be a path for you to go down.
Examples of scripting languages are Perl, PHP, Ajax, and JavaScript. For most programs, you
could probably use a general purpose language. General Purpose languages, as they sound
have a wide range of applications. Usually, these should be your go to languages. Examples
of general purpose languages are Java, c++, and Python. They each have their own different
benefits over one another. Java is very useful for developing games and interactive web pages.
Python can act as a scripting language for web programming, as well as writing applications
and data analysis. And c++ tends to be used for writing applications and system programs. They all
have a variety of packages that you can import and use to achieve the functionality you need from
them. while selecting the right general purpose language for your big projects is very important.
For most of your programs, any one of them will work. It really comes down to preference. Get to
know each language and decide which ones syntax rules you like best and find most comfortable.
If you get to know one general purpose language really well and enjoy programming with it, you
can apply it to just about any of the programs you plan on writing. Personally, I tend to use
Python for most of my projects. This is mostly not due to any functional difference between
Python and any other general purpose language, though there are a few, but it is mainly because
I find it syntax rules most convenient and easiest to write programs with. Overall, either you
can consider the product you plan on doing and research and see which language boasts the most
advantages for your purposes. Or you can simply become comfortable with a language and use it for
most of the programs you decide to write. will now be looking at our final topic of this introduction
to programming miniseries, you now have the basic knowledge of programming, which will take you
far in any language that you decide to learn, you know, some good pre programming pseudocode
strategies to help you design your code from the ground up. And you might already have a good
idea as to the type of programming language you might want to start with. So what's the next
step? How can I learn that language? And what applications can it be used for? Well, that's
what we're going to be covering now. So let's just jump right into it. Starting with the biggest
question, which is what is the next step? Well, now that you might know which type of language
you might be interested in, research that language and find out whether or not you truly want to
pursue that programming language. Most languages like Python or c++ will have either an official
website where you can read up on the language, or Wikipedia page, which will provide you with
useful information in deciding whether or not you want to pursue that path. From there, the
next step is to actually learn the language, which can be done right here on YouTube. While
we've taught you the basics of any programming language, each specific language is going to
expand upon these concepts. And so watching tutorial videos on a certain language is going
to be very beneficial. I would start with an introduction series, like the one you're currently
watching both for the language you've chosen and work your way through that series, picking up on
the syntax and rules of that language until you become comfortable with it. Once you do that, you
come to a crossroads. You know how to program in a certain language, but you may be completely
clueless as to what to make in that language. Programmers blog can leave you uninspired and
not want to continue programming. So I'd like to give you a few websites to help out. First
is coding bat, a completely free website which has hundreds of coding challenges in both Java and
Python to help you refine your programming skills, and even learn some new programming shortcuts and
tips. This is great if you want to get better at improving your efficiency and need something to
hone your skills as a developer. The next is coder bite, which offers over 200 plus challenges that
you can complete in over 10 different languages, something that is sure to help you improve. The
final website I'd like to talk about is hacker rank, which not only provides programming
challenges to keep you on your toes, but also provides support for you using your
programming skills to find jobs or internships. These and many more websites exists solely to
keep you interested in code and work on refining your skills to become better. Now if you're a
teenager watching this series in high school, I also encourage you to take programming
classes in your high school. AP Computer science principles and AP Computer Science a are
both amazing courses which can help you greatly in the future, and are also incredibly informative
and important to colleges. Your school might also offer other classes in the field of computer
science, including ones on key data structures, game design, and data science. Any and all classes
you can take to help expand your knowledge of programming and help you find your niche is going
to be extremely helpful. As you can see, the world of code has now been opened up to you. These are
just a few examples of where you can go from here. But there are many more we didn't talk about. You
could get into GitHub and start contributing to projects. You could work on your own projects
and collaborate with others. The possibilities are endless. The next step is up to you. This
concludes our introduction to programming mini series. We hope you enjoyed watching it as
much as we enjoyed making it. If you enjoyed the series as a whole consider subscribing to
our channel, no pointer exception, which will be linked in the description for more content like
this coming soon. Thank you so much for watching.
