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All right.

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Let's talk about functions now functions are what I like to think of as many programs.

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It's like this organized block of code that you you define and then you can call it later and makes

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a lot simpler than typing everything out.

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So it's a lot easier to visualize this than me to just talk.

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The theory of it.

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So let's go ahead and let's g r our script again our script up high and then we're going to Ampersand

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this one this time and we should have our python script from before I'm Mrs. scroll down to the bottom

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and I'm going to add in a new section here in that section and just going to be called functions.

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So if we want to print out we can print out a new line to kind of put this together and then maybe when

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it's all said and done we can print a function or make a function that just prints and make it a little

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bit easier for us.

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So we're going to print a line here defined functions and maybe we'll just print out something that

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says Here is an example.

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Function so this is really just going to define the area.

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If we save it while you're typing years I'm just going to print mine so well Python 3 script that pi

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and you see we've got the new line here and we see here is an example function and we just start from

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here.

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So let's take a look at a function using something that we've already done before.

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So we've got this section here and we've got name age GPA we're going to kind of reuse this and this

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print my name is.

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So let's go ahead and reuse this.

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We're gonna say function here.

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Right.

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So we're going to define kind of.

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Who am I.

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So we're going to define this and then we're going to do two parentheses and then a colon here.

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So it's going to look like this.

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And what's important now is that we use indentation.

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Now we haven't had to talk about indentation to this point but python is very very critical on utilizing

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indentation.

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If you don't use it in the right places then your program will not function.

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So it's very important to know when to use indentation into indent properly so to indent.

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I'm just going to tab here and I'm going to redefine everything again so we can just say name equals

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Pete and we can just say age equals 30 type that wrong there and then we can just copy this print right

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here so we don't have to type it all out again.

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Copy and paste it and you can see define who am I.

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And we're going to define in this function a name variable and age variable and then we're gonna print

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this out.

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So if we were to just go ahead and save this and print this Nothing nothing's here.

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All we've done so far is just define this function.

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We have done nothing to actually call it or or do anything and let's make a note here that this is a

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function.

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Right.

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So when we get down towards the bottom let's go ahead and just try to call this function.

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So to call a function all we got to say is Who am I and let's go ahead and save this.

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Run it again and look.

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It says My name is Heath and I am 30 years old.

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Well what's happening here.

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OK.

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So we're defining a set of things to do.

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Right.

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This is a mini program inside this mini program.

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We've defined our variables and we define an action here to take which is printing out this string.

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So what it's doing is when we call this it's saying Hey I'm gonna go ahead and take all this and I'm

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going to run this program and give you the result.

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Now what's important to know is whatever is stored in these variables here is only stored there inside

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the function.

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If we were to print age from the last video it should still be thirty two I do believe.

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So it's print and you'll see it's 32 even though we declared age up here as 30 that only lives inside

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this function.

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So I'm going to go ahead and delete this.

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So again everything is living inside this function and it's a mini little program that we have here

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and we just call it at a later time.

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So let's go ahead and build out another function and we can kind of start to make sense of this.

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So let's start with adding what are called parameters.

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And will this do adding parameters here so let's make a function and this function is called add one

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hundred like this OK and then the parameter I'm going to actually add inside instead of giving empty

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parentheses I'm going to add in something called num.

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It's just going to be for a number and then we're gonna go ahead and use our colon it enter you a tab.

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And then what I want to do is I want to print no floss one hundred.

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So what am I doing here.

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I'm taking a number and I'm adding 100 to it.

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So my function of adding one hundred makes logical sense.

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OK.

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So what's going to happen then if I say ad one hundred and then I specify a number in the parameter.

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Well I'm going to say what if I want to add one hundred to one hundred.

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Well then I should in theory print out two hundred right.

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And there you go.

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We have successfully printed out two hundred so we can build upon this even more so what if we want

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to use multiple parameters.

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OK let's say we want to do multiple parameters and we want to define an add function.

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We're just gonna make an ad even that's built into Python we're gonna make our own.

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So we're just going to say add x and y.

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So now we have two parameters here going add our colon.

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Make sure we indent and then we're just gonna say print x plus y.

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Now if we go in and we add seven and seven we should get 14 and there's 14.

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So hopefully this is starting to make sense.

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All we're doing is building these mini programs and we can have no parameters as we saw here.

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We can have single parameters or multiple parameters depending on what we need.

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So let's go ahead and build a couple more out.

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Just to make sense of it.

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So what if we wanted to define multiply and we'll just say x y again.

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What do you think that's going to look like well instead of saying print what if we say return and throw

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something new at you going to say return x and y OK.

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Now what happens if I call multiply and I say 7 7 again what happens here.

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Go ahead and save it.

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Well nothing happened.

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We're not printing out to the screen.

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All we're doing is returning.

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So when I'm pulling this multiply in it's returning a certain number.

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So I'm calling it here and it's saying hey seven times seven.

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That's forty nine.

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But I have no idea what you want me to do with it.

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Now I could say branch multiply here and then we can see what happens.

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And now you see it's forty nine.

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So the return feature just allows us to return the number that is back to us.

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Right.

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We don't have to always print it out if we don't want to.

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We can store it for later.

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So that's what we can do here.

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So we don't always have to print it.

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We can.

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We can return the number and then call it later.

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So that's one way of looking at it.

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Let's do one more.

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How about we define square it

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and we only take one number here.

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So how would we do the square root of something.

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Well let's go ahead and just print out x and then we're going to do by point five.

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Remember the exponent with two multiplications here and then we're doing the square root.

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So we're going to take point five instead of squared which would be two.

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Right.

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So we're taking the square root do point five.

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And let's take an easy one Let's return the square root of sixty four.

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So let's say square root of sixty four and see what happens.

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And it returns eight for us.

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Now we can make that integer if we want to and go from there.

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But that's just a nice base example so lastly I mentioned that we can make a function for a new line

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because we've been sitting in here and we've been just typing print and I am slow at it.

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I have to sit here and think about it and then I find the correct letters and this is how you print

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new line.

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OK.

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I'm not the best at it.

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But what if instead we just did something like define new line and then we just put this here.

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So then we can just call a new line from here on out.

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We could say a new line.

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And then when this prince will print out a new line and while it's the same kind of length ish of this

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we don't have to type in these special characters look for them we could even shorten this to like an

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L something like an L and then make it really simple and then we save time.

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And this is where these programs come in and they save time.

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So good example of a use of a function.

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So I'm going to save this if you want to use this for moving forward in going on in the next videos.

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Absolutely welcome to.

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So if you're following along go ahead and just leave your text editor open and I will catch you over

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in the next video as we start to talk about boolean expressions.