Variables

Quick reference

• 00:03 Okay, in this video I want to start to talk about variables.
• 00:07 And variables are probably the most important fundamental building block of
• 00:11 all coding, not just C# but any programming whatsoever,
• 00:15 variables are the most important basic element.
• 00:18 And a variable is basically just like a box or a bucket.
• 00:21 It's a thing you can put other things in.
• 00:24 And there are tons of different things that you could put into variables from
• 00:28 text to numbers to dates to other variables, mind blown.
• 00:32 To arrays and functions and all kinds of things you could stick into variables.
• 00:36 And we're going to get into the different types of things you can put into
• 00:39 variables later, specifically data types, but for
• 00:42 now I just sort of want to talk about the concept of a variable.
• 00:45 So I think of a box, what do you use a box for?
• 00:48 You put something in it, and you might need that, whatever that thing is now,
• 00:52 you can take it back out.
• 00:53 You might hold it in there for later.
• 00:55 In your program later on, you might reference it.
• 00:58 You might just stick it in there to sort of categorize it,
• 01:01 to sort of keep track of it.
• 01:02 And a variable's the same thing, it's just a place where you can put something to
• 01:07 keep track of to take out later.
• 01:08 Now you can change what's in the variable.
• 01:10 You can add different things.
• 01:12 You could add stuff to it, you could take stuff out of it.
• 01:14 It's just a very useful and fundamental programming thing.
• 01:17 So you're always going to use variables, you're always going to have them.
• 01:21 And they're super easy to use.
• 01:22 Now in a lot of programming languages, you could just use variables.
• 01:26 C# is a little bit more complicated, you actually have to define the variable,
• 01:29 explain exactly what you're going to use it for, and then use it.
• 01:33 So it's kind of a pain but that's just the C# thing, C's sort of like that.
• 01:37 Your different C programming languages are often like that.
• 01:40 Now you can do all of those things usually on one line.
• 01:43 You can define it, put something in it, and start using it all in one line.
• 01:47 Or you can break that into separate lines and I'll show you each one.
• 01:50 So we're going to get into the different types of variables in the next few videos.
• 01:53 In this video, we're just going to talk about strings and
• 01:56 strings are just strings of text like this right here, hello world.
• 02:00 That's a string, right?
• 02:01 It's just basically text of more than one character.
• 02:04 So to create a variable with string,
• 02:07 we just first define string and then we name it.
• 02:11 So let's call this first name, so here we've defined our variable, firstName.
• 02:18 So it exists and now we can use it, so we could use it by assigning something to it.
• 02:25 So we use an assignment operator, which is in this case, the equal to sign.
• 02:29 And here we could say, John.
• 02:33 Now notice at the end of each of these lines, I'm putting a semicolon.
• 02:36 That's totally normal with C#.
• 02:38 You're going to do that usually at the end of most lines of code that you write.
• 02:41 So here we have it, we've got a variable.
• 02:45 Now, down here we can use that variable.
• 02:46 Instead of this, we could say hello, and then concatenate it,
• 02:51 put a little plus sign, and then we could just put that variable, firstName.
• 02:58 So if we run this, we see it says hello John, very cool, and that's variables.
• 03:04 So this is a very basic example of defining and assigning a variable and
• 03:08 then using that variable, so, very cool.
• 03:11 Like I said we could do this in more than one line, like this.
• 03:15 We could do the same thing.
• 03:16 Let me comment this out and two slashes, that is a comment, two forward slashes.
• 03:21 That's a comment, so you can see it sort of greened it out.
• 03:24 We could do the same thing.
• 03:25 We could go string firstName equals John,
• 03:30 and now we've done it all in one line.
• 03:34 So if we run this, We get the same exact thing, Hello, John.
• 03:40 So sometimes, it just sort of makes sense to use two lines.
• 03:45 Most of the time, you'll just use one line and just sort of knock it out like that.
• 03:49 It really doesn't matter which.
• 03:50 A lot of times if you have a complicated program,
• 03:53 you might want to define all the variables at the beginning of the program, and
• 03:56 then later on you can assign things to them as you need it.
• 03:59 In that case, you would do it this way,
• 04:01 you would just define all of your variables, and then later on in
• 04:04 the program you would assign things to those variables as you want.
• 04:07 Now we can change things, like I said, a variable doesn't have to stay the same.
• 04:11 We can also then go firstName = Bob;.
• 04:16 Well, now if we run this, what do you think is going to happen down here?
• 04:21 Well, let's go ahead and see.
• 04:25 It says Hello Bob.
• 04:26 Why is that?
• 04:27 Well, we assigned John to firstName, how come it says Bob?
• 04:30 Well, this is a matter of program flow,
• 04:32 program flow starts at the top of the programming, works its way down.
• 04:35 So C# sees this, says, firstName is John, but then it comes to this line,
• 04:39 it says, wait, nope, it's Bob.
• 04:41 So it replaces what's in there with Bob, and then it prints it out, Bob.
• 04:46 So get rid of that, like I said we're going to use variables all the time, and
• 04:49 we're going to talk about them in much greater depth in the next few videos.
• 04:53 Like I said, there's all kinds of things you could put into variables.
• 04:55 In this place we've just put a string of text, but there are numbers, different
• 04:59 types of numbers, floats and integers and all kinds of different things.
• 05:03 There are concepts you could put in like true and false.
• 05:05 We'll talk about that later on.
• 05:07 You could assign arrays, different hashes, and dictionaries, and lists and
• 05:11 all kinds of things, and we're going to get into all that as we go forward.
• 05:14 But in this video I just want you to wrap your brain around the concept
• 05:17 of a variable.
• 05:18 It's like a bucket, it's a box, you can put stuff in it, you can take stuff out,
• 05:22 you can change it, update it, add stuff to it, and
• 05:24 we'll talk about all those things going forward.
• 05:26 And that's all there is to it, so that's variables.
• 05:29 In the next video we'll start to look at data types.

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