Variables and DataTypes

Tinashe Matanda

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00:00Hi folks, welcome back. So, previously we've just gotten a chance to play around with

00:07what the queen state means. So, let's clear this out. Alright. And I'll clear out the

00:14variables as well. Now, we're going to play around with variables. How can we create variables?

00:22What are variables? So, a variable is essentially a word or a key that maps out to a certain

00:30value in memory, right? So, when you're creating your code and so on and you're playing around

00:36with mathematics maybe or whatever, essentially you're playing around with variables, right?

00:41You're taking values, you're taking numbers, words and so on and you're distributing them

00:46around the memory of a computer. And variables allow us to essentially map and access those

00:54different values. Okay. So, variables essentially they store information, they are a container.

01:00So, that's what we have an idea of. I'm going to use this hashtag by the way. If you want

01:04to write notes or comments in your code but you don't want Python to process it as if it's

01:09code, just put a little hashtag next to it. But nonetheless, let's talk about those variables.

01:15So, variables, yes, they represent information. They store information. So, let's talk about

01:20information. How can we store information, right? What kind of information can we store?

01:28So, we're going to process these in parts with what are known as integers, right?

01:33Integers. So, when we create an integer, for example, an age can be represented as 26, for example.

01:41And yes, you need the little equal sign because that's what we use to push a value to a variable.

01:47So, here I'm initializing a variable age and I'm giving it the value 26. That's an integer,

01:53right? So, an integer is essentially a whole number, right? So, it's a whole number, right?

02:01And yes, positives and negatives are like, okay? So, an age can be something like that.

02:09Bank balance. Yes, variables are one word. That's why I'm using the underscore. Balance is going to be

02:16equal to negative 5, for example. Do you see that? That's a negative. It's still a integer, okay?

02:24Then there might be cases where you want to work with partials. These are what we call floats,

02:27right? A float. A float is basically a decimal point value, okay? So, let's give it an example.

02:37Maybe perhaps I want to represent pi. That would be 3,1459, da-da-da-da-da, right? That's a float.

02:46And yes, this is obviously positives and negatives as well. Fair enough? Now, this is in terms of

02:55numerical values, of course. Then there might be cases where we would like to represent words,

03:00right? This is what we call a string, right? A string is basically a sequence of characters,

03:10okay? And take note, strings are normally encapsulated in between quotations. Like previously,

03:16when we played around with the print statement, you notice that we used the quotes to put around

03:23the hello world, or hello jack, or hello jones, and so on, right? And there's the example exactly.

03:29So, what we have here is a string. It's a sequence of characters. They are words, right? So, for example,

03:36I could have a name and set this to Peter, for example, right? It's okay like that, but it's not

03:42okay if it is not in quotes, right? You'd actually notice that spider screams in your face because it's

03:48saying, hey, this is an undefined name, Peter, right? Because take note, if it's not in quotes,

03:54it's going to be taken as if it is a variable that you already created. So, you might want to put quotes

04:00around it, right? Like that, okay? I'll just get rid of that finishing one day. Okay, then we have cases

04:11where we have these things known as booleans. Now, a boolean is a bit odd. So, a boolean is a true or

04:19false value. Okay? So, for example, I could say is married is equal to false, right? Is equals to false,

04:30and that's very much it, right? And at some point in time, maybe I want to do something. If someone is

04:35married, I could just say, if is married, then do this. So, it sort of makes that processing a whole

04:40lot quicker. It's sort of a question that can be answered quicker as well. So, it's pretty cool,

04:46right? Now, the question is, how do you access a variable that you created, right? That's a question.

04:56How do you access a variable you created when accessing a variable that you initialized as proper

05:02terminology states? So, let's do a little print statement here, right? I'm going to say hello

05:09in a line of its own, right? And then I'm going to print out a name. You're just going to use the

05:15variable name without quotes, right? If it's in quotes, it's taken as a string, but without quotes,

05:21then it will access that particular variable. So, if you're running this, notice how we've created all

05:26those variables there in our variable explorer. See, notice age is an integer of size 1, which is

05:34good, and it holds the value 26. Bank balance is also that despite the negative, because again,

05:40integers are positives and negative values, right? The same is married. Notice how that's a boolean

05:47that says false. See, name is string, float, spy, and so on and so forth. And yes, we do get our outputs,

05:55hello, and pt at the bottom. Let me just point out, when it comes to this print statement, we have what

06:03are known, what is known as formatting tags and concatenation. So, concatenation happens where you

06:09somewhat combining things together. Like, hello, I can concatenate this with a nice little plus

06:15and say world, like so, right? So, what we have here is hello, concatenation with world. These are

06:22two different strings that I'm concatenating, by the way. And if we run these, we can get that output

06:27of hello world. This is what we know as concatenation, right? The ability to join those things together,

06:35which is good, right? In the end, you'd actually notice when you build some programs,

06:41concatenation comes in handy. But I must point out, it's a different case when you're concatenating

06:47numbers, right? Such as 9 plus 9. 9 plus 9 would not give you 9 and 9, it would give you 18.

06:56Because those are numbers, right? Those are integers. So, if you have a plus operated on integer

07:01values, you're going to have it look like that. Unless we sort of have a number A, and we gave

07:09it a string, see why the quotes are important. And we have a B, and we have a string. See,

07:15now they are not integers. So, if I actually use the plus operator this time, A plus B, if

07:23I use the plus operator, I'm not going to get an 18. I'm actually going to get something

07:27a whole lot different. I'm actually now going to get a 99. Because there's strings, it concatenates.

07:33So, if you're using the plus operator, where you have two strings, right? You are essentially

07:39going to get concatenation if you have two strings. If you have two integers, you are going to get

07:45addition rather than concatenation. Okay? That's what we call concatenation. And there might be a case

07:51where you want to join two things together. We can use what is known as formatting. Formating happens

07:56now when there's a variable, and there's a nice little slot where you would like to put

08:00it in. So, let me put it like this, so it makes sense. We would say, hi, whatever your

08:08name is, right? Variable name, right? We actually put it in curly braces, like that. And I may

08:15say, it's nice to meet you. See, notice how our variable, we would like to put it right in

08:22the middle of a lot of nonsense. So, formatting happens where you do this, but there's a nice

08:27little if that you have to put in front to basically show and represent that you are performing

08:33formatting. That's what formatting tags are. So, this little if, and in curly braces, we

08:39put the actual variable name, which is name of Peter. So, that's why we get that, hi, Peter,

08:45it is nice to meet you. So, that's sort of the idea when you're working around variables,

08:51and how you can use variables to perform concatenation as much as formatting for you to display a much

08:57cleaner and meaner output. Last but not least, let's just talk a little bit about the arithmetics.

09:03Remember how we performed addition? That's addition. Subtraction, we use the hyphen. Division, we

09:09use this. And multiplication, we use the asterisk. This is how you can perform basic arithmetics.

09:14using hyphen. However, with this in mind, there's obviously further mathematical operations that

09:23we can do, such as exponents, or roots, right? Radical signs, and so on and so forth. For

09:30us to do this, we cannot do this with the nature of the standard math as it is, but we can use

09:38a math library. By now you have an idea what a library is. We can use a library to do precision

09:44precisely that. But we'll be looking at some of those at a later stage. So, for now, let's

09:49close it right there, and I shall see you guys in the next one. Cheers!

09:53Thank you!

09:54Thank you!

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