Functions

Quick reference

• 00:05 In this video, I wanna talk about functions.
• 00:07 Now PHP has over 1,000 built in functions, and
• 00:09 we're gonna look at some of those a little bit later on.
• 00:11 But in this video, I wanna talk about creating your own functions.
• 00:15 A function is basically a little program inside of your program, and
• 00:19 it doesn't get run immediately when your program runs when your page runs.
• 00:23 When something comes to your website, whatever,
• 00:25 a function only gets to run only if you call it specifically within your program.
• 00:29 We're gonna look at that now.
• 00:30 So to create a function, it's pretty simple, we just type in function, and
• 00:35 then give it a name, and let's call this mathing.
• 00:38 We're gonna do some math.
• 00:40 And then you do these two parenthesis, and
• 00:43 then your squiggly bracket thing and that's it.
• 00:45 So we now have a function, now there's nothing actually in this function.
• 00:49 We would do something inside of here, to do something,
• 00:54 and we'll do that in just a minute.
• 00:55 Now to call this function you just type the name of it, mathing,
• 00:59 the little (), and of course your ;.
• 01:02 Now, this calls the function.
• 01:07 Let's actually do something here.
• 01:09 Let's write a function.
• 01:11 And let's say echo 2 + 2, if we remove this lines,
• 01:16 save this, come back here and hit reload, nothing happens.
• 01:19 Because like I said, with the function, it only runs if you call it.
• 01:23 So to call it, we just name it, and if we save this, hit reload, boom, we get four.
• 01:28 Now, we can actually pass things in to a function from the outside world, and
• 01:33 those are called parameters.
• 01:34 We can pass a parameter in.
• 01:35 Let's say we wanna pass this in a couple of numbers, and do some math with it.
• 01:39 So let's call this num1, and num2.
• 01:44 Inside of this program, we can use these variables.
• 01:47 So let's go num1 + num2;.
• 01:53 Now we've set up our function to take in parameters,
• 01:56 in order to then send parameters to our function, and in order to send numbers,
• 02:00 we put them right here, when we call the function between these two parenthesis.
• 02:04 So if we had 2 and 3, the number 2 becomes this num1 variable,
• 02:10 get shoved into this variable.
• 02:13 And number 3, get shoved into this num2 variable, and
• 02:16 then get passed into our function, save this.
• 02:18 And if we look at our program, it's just going to echo out number 1 + number 2,
• 02:22 which in this case is 2 and 3.
• 02:24 If we've done our job correctly, we should get 5, so hit reload and boom, 5.
• 02:28 And of course you can change these around for 41 and 3, 44.
• 02:33 It's not just numbers, and you can pass absolutely anything
• 02:38 in if we wanted to concatenate instead of add, and if we wanted
• 02:43 to do strings instead of numbers, we could easily do John and Elder, now.
• 02:49 Num1 becomes John and num2 becomes Elder, and
• 02:52 it will concatenate these two together and out put the JohnElder, there you go.
• 02:58 We could also do, put a space in there, whatever you want,
• 03:02 you get the idea, John Elder.
• 03:04 Functions are very important and they're very powerful.
• 03:06 They're like little programs within your programs.
• 03:09 And remember, they don't get run automatically,
• 03:11 they only get run when you call them.
• 03:13 And the cool thing is, you can call them over, and over, and over again.
• 03:16 I mean, whenever you want from now on, you can call this function.
• 03:20 So if we can quote three more times, and we get boom, boom, boom, three more times.
• 03:26 We could, let's see, up here, play around with this a little bit.
• 03:30 Add a line break just for fun.
• 03:32 Boom, Boom, Boom.
• 03:35 So you see, very powerful.
• 03:37 Every programming language has functions.
• 03:39 Some programming languages call them methods.
• 03:41 I know in Ruby, they call them methods.
• 03:43 But in PHP, they call them functions, and it's just a fundamental part of
• 03:46 programming, and you'll use functions all the time.
• 03:48 So in the next video, we're gonna look at random numbers and dates.

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