Arguments and Parameters4:31 with Ashley Boucher
How about sending data to a function?
Welcome back. 0:00 Now that we've discussed returning values from functions, 0:01 we're going to build on this by learning how to send values to functions. 0:03 We've been using some pretty simple examples so far. 0:07 Our function that adds two plus two together wasn't very interesting, 0:09 even after we returned a value from it. 0:13 You might be thinking I still don't get why functions are so useful. 0:15 Well, let's expand on this. 0:19 Our 2 plus 2 function would be a lot more useful 0:21 if we could use it to add the number 2 to any integer and we can totally do that. 0:24 Just like functions can send values back via a return, functions can receive 0:29 values too and they can see, access and use those values inside the function. 0:34 This is all done by what’s called passing an argument to a function. 0:39 There are two parts to this. 0:43 First, when we call a function, we can send a value. 0:45 Second, the function has to be written so we can receive that value. 0:48 Have you ever wondered about those pesky parenthesis we have to 0:53 add when defining or calling the function? 0:55 Those parens are where the sending and receiving of values takes place. 0:58 Let's revisit our two plus two function. 1:02 Okay, first, I'm gonna change its name. 1:05 Instead of 2 + 2, I'll call it add_two. 1:07 This new name makes more sense because we're gonna modify this function so 1:13 it now adds 2 to whatever integer it receives. 1:17 Now inside the parens, I'm gonna create a variable. 1:20 I'm gonna call it num. 1:23 Right now num has no value, it won't be assigned a value until the function is 1:25 called and a value is passed but we'll get to that in just one moment. 1:29 Now that we've created a variable inside the prints, 1:33 this special kinda of variable is known as a parameter by the way. 1:36 We can use it inside of our function just like any other local variable. 1:39 That means we can change the body of our function like this. 1:43 What we've done here is rewrite our function so that it can receive a value, 1:50 which is stored in the parameter variable called num. 1:53 And then we can use that value inside the function. 1:57 So how do we send that value to our function? 2:00 Well, this happens when we call it. 2:03 First we'll rate a regular function call to the add_two function. 2:04 To send a value, we add it inside the parens. 2:12 This value is called an argument. 2:15 An argument can be any Python data type or expression that evaluates to a value. 2:17 This means you can pass in an integer, a string, a function call, and 2:22 even other Python data types that you haven't learned about quite yet. 2:26 In our case, we're just gonna be passing an integer. 2:29 Let's pass the number 5. 2:32 Now, like we learned earlier in this course, 2:35 not much will be visible to us if we run our program right now. 2:37 To add some clarity to what's going on behind the scenes, I'll add a print 2:40 statement inside our function that prints out the value sent to the num parameter. 2:44 Now when I run this we can expect the output to be five, let's double check. 2:53 Awesome, just as I expected the output here is 5 because when we called 3:05 the add_two function we passed the integer 5 as an argument to the function. 3:09 This value was received by our function and stored in the variable num. 3:15 Num, now referencing a value of five, 3:18 can be used like any local variable inside the function. 3:21 I hope you're getting the hang of arguments and 3:25 parameters when you're ready, 3:27 come join me in the next video to talk about handling more than one parameter. 3:29 Also don't forget that you're doing great and you're learning things that are going 3:32 to help you be more experienced and capable programmer. 3:35 If you're struggling, it's okay. 3:39 Treehouse has tons of resources to help you support you while you go through 3:41 your coursework. 3:44 The Treehouse community is an excellent place to connect with other students and 3:45 ask and answer questions. 3:48 Watching videos a second time can also help you absorb information. 3:50 Sometimes you really need to hear things two or 3:54 three times before a concept really starts to sink in. 3:56 Think about a time when you've watched a movie a second or third time. 3:59 How much more did you pick up or notice, learning programming is a lot like that. 4:02 And finally don't hesitate to practice, there is no wrong way to practice or 4:06 learn and trying things out in your terminal is a great way to 4:10 understand what's happening in your code without worrying about breaking anything. 4:13 Taking advantage of Treehouse's practice sessions is another way to gain 4:18 a real advantage in your skill development. 4:21 Remember, just have fun and always keep in mind that even professional and 4:24 advanced programmers are always learning and getting better too. 4:28
You need to sign up for Treehouse in order to download course files.Sign up