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So friends, in a previous skill we discussed the concept of variables with

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respect to Ansible.

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So what we're going to do now is to discuss the same type of subject this time

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in the context of

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the Python programming language. So pretty much the same concepts do apply.

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This is going to

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allow us to effectively work with dynamic values as opposed to, you know,

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typing in static hard coded

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values. And in the world of programming, this really is very, very useful now

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with respect to variables.

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Variables are honestly one of the most, what would you say? Well known, well
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Variables are honestly one of the most, what would you say? Well known, well

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used,

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popular concepts in all of programming. You can see this within the go-line

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programming language.

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You can see it within Python. You can see it within C. You can see it in pretty

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much all programming

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languages. So this is not an overstatement to say that the concept of variables

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is a core component,

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a core fundamental practice of programming. Basically, what I'm telling you is

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that what we're

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learning here is really, really useful. Okay, so hopefully I have convinced you
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learning here is really, really useful. Okay, so hopefully I have convinced you

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to pay attention

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and to understand that this is important. With that said, let's see how we can

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actually work with

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variables within Python. So check it out. What I'm going to do is I'll just

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create a little folder

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here and let's just call this Python stuff. Okay, and let's just change into

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this directory here.

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Okay, now what I will do is I will create a little file here and I'll just call

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this example.py.

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This can be an example Python felt that we can use to explore our variables. So

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I'll just open this

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up right here. Okay, okay. Now before we actually start the very first thing

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that I should say is that
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that I should say is that

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Python happens to be a dynamic programming language. What this means is that

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with respect to data

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types, Python really does not care. It's going to allow you to assign a

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variable without specifying

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the type of data that you want to store. What on earth am I even actually blab

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bing about? Well,

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we'll actually talk about data types in the upcoming video. But just for the

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moment, understand that when

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we assign a variable value, it's going to be accepted dynamically with Python

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and we don't have

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to specify the type of data. Okay, so whatever the types can be, we'll discuss
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to specify the type of data. Okay, so whatever the types can be, we'll discuss

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that very, very shortly.

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Now just to be clear here, what is actually happening is that when we happen to

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assign a variable,

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we are essentially putting a value in a placeholder that has ultimately been

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kept in memory. Okay,

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and when we want to retrieve that value, well, this placeholder here basically

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points to that

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particular point in memory and we can retrieve the value sound complex. Well,

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it really isn't. Let's

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actually see an action then. So here is how we can assign a variable value in

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Python. It's really

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really hard. You're going to have to really focus. Let's just say I wanted to
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really hard. You're going to have to really focus. Let's just say I wanted to

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create a variable called,

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well, I don't know, let's just say food. Now to assign this a value, I just use

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the equal sign,

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and then I just correlate the value that I want to pass in and that is it. No,

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really that is it.

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This is how we actually assign variables within Python. We've got the variable

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name and we have

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associated this with the variable value. So what I can then do is I can say

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print out the food variable.
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print out the food variable.

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And if I just save this and I run the script by saying python3example.py and to

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enter,

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what we're actually doing is printing out the value that is associated with

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this variable.

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Now here is the thing. If I want to actually see whereabouts in memory this

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particular value is stored,

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I can also use this particular function known as the ID function. Okay, if I

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just save this as

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opposed to printing at the value, we're essentially going to see the memory

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location. This is exactly where

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the data happens to be stored within my computer. Now this might be a little
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the data happens to be stored within my computer. Now this might be a little

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bit esoteric,

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but let me just show you why this is actually quite important. Say for example,

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I wanted to update the

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value of this particular variable. What I could do is just simply reassign it.

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I'll just use the same name

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and then also equals and then just give it a new value. Let's go with, I don't

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know, let's go with

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cheesers time. Okay, so now if I print out the food, here's what's going to

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happen. We create a variable

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called food, assign it pizza at this point in the program when you print the

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variable, the value
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variable, the value

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will be pizza. However, we can then overwrite it here, give it a new value and

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at this point in the

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program, when we print it out, we're now going to see cheesers. So check this

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out if I run the program

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one more time. Look at this right here, we print out pizza, then we print out

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cheese. Notice though,

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if I happen to print out the ID, what do you think is going to happen is the

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number going to stay the

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same or is the number actually going to change? We know the value definitely

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changed, but let's see

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the actual place in memory. So let's run the script and as we can see here, we
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the actual place in memory. So let's run the script and as we can see here, we

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actually have two

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different values. The first one ends in 040 and the second one is in 104. So

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essentially here, the

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actual value is not being modified, it's really been rewritten entirely in a

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new memory location.

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And now the variable value as to find here is simply pointing to a new place in

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memory,

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industrial retrieving this new value. Now here's a thing with respect to the

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naming of our variables

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that actually are some particular rules. What we can do is we can write names

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of variables in
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lowercase if you so wish, we can also do the same by utilizing uppercase. We

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actually can use

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digits in the name of a variable, although a variable cannot start with a digit

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. And we can also

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utilize underscores and this actually is very, very common. It's a nice way to

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separate out long variables

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to make them a lot more readable. Now one thing we do not want to be utilizing

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as our variable names

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is special characters. So things such as you know like question marks or

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percentage signs or maybe

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the at logo or the hashtag that type of thing, these are not going to be
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the at logo or the hashtag that type of thing, these are not going to be

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accepted. It's just going to

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give you a problem when you try to run your script. Let me just show you how

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that actually operates.

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So we know I can say food is equal to pizza and let me demonstrate that it's

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okay to use capital

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letters here. So let's just print out food. There we go. And let's run the

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script. There we go.

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As we can see, we can use things like underscores. We can say my food and again

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, let's just

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reference this as we print it out. Save you. Arru up. Try again. Print out no

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problem. We can

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add in digits such as my first food. If I go to print this out, run it again.
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add in digits such as my first food. If I go to print this out, run it again.

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There'll be no problem.

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But what I can't do is I can't start the name of the variable with the number.

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Okay. If I save this,

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we can actually see already here. We're getting a little bit of a warning with

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this quickly line.

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If I run the program, we're just going to get an invalid value here. Okay. So

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be aware of that.

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Similarly, we can't use special characters. So I can't say, you know, my ad for

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my email and just say

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john@example.com. If I try to save this and print it, we're going to get an
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john@example.com. If I try to save this and print it, we're going to get an

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error one more time. However,

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if I change this to be, you know, my email, again, this will be my email, save

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you. Run it. It's

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going to work just fine. Now one last thing I just want to point out with the

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use of our variables

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is that it's really quite important, at least with the readability of your code

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to use

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meaningful names. Okay. So don't actually just name things randomly. This is

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just going to serve to

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confuse people who look at your code. In fact, it's probably going to just

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confuse you further down

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the line when you revisit old code. Okay. So don't do it. What do I mean? I say
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the line when you revisit old code. Okay. So don't do it. What do I mean? I say

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this. Well, don't say

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food is equal to and then give like an email address. Okay. Technically, well,

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this is absolutely

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going to work. It's not going to break Python after all. Okay. This here is

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just a placeholder for

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this value and it's actually conforming to the rules of Python. It's in lower

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case, not using

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special characters, so on, so forth. So if we run it, it is going to print at

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the value. But when you

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have tons and tons and tons of code, lines of codes, this is just going to give

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you a headache. It's

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going to make troubleshooting really quite awkward, really try to avoid it.
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going to make troubleshooting really quite awkward, really try to avoid it.

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Definitely do not do it.

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So those are some of the basic bones of actually creating variables and

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updating these values. We

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know some of the rules about how we can actually name them. With that now said,

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let's take a look at

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some of the data we are assigning to our variables by first talking about these

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data types.