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‫Hello and welcome.

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‫In this lecture, we're going to be looking at how we can return values out of our functions using different

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‫return types and a return statement.

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‫Let's dive in and see how this works.

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‫So last lecture, we said that if our function doesn't return a value, then the return type should

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‫be void, which is what we've done here.

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‫But what if we wanted to take a function such as get basically checking whether we should turn around

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‫this function here in the if statement, if we could say should turn around instead, it would be a

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‫much cleaner function at the end of the day.

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‫So how do we do that?

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‫How do we achieve a function that can return a Boolean expression?

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‫Well, the way we do it is simply by using a type instead of the void.

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‫So if we were to want to return a boolean expression because type bool like we would for a variable.

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‫But the thing that distinguishes the function from the variable is the fact that we put parentheses

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‫after it that makes it a function rather than a variable.

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‫And what we could do is call it should platform return and then we put our parentheses.

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‫And in this case, I don't have anything that I want to pass in as an argument to this function, so

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‫I can just leave the parameter list empty, put semicolon at the end of the line and then copy this

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‫entire line and go over to the moving platform.

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‫CP And right at the end of the file you could put it anywhere you like really between any of the functions.

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‫Just make sure it's not inside a function.

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‫I'm going to paste it in here.

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‫I'm going to indent it and I'm going to add the class and.

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‫The scope resolution operates.

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‫So a moving platform colon colon should platform return, then remove the semicolon, add some braces

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‫instead.

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‫And what we want to do here is if we want it to actually return a result, we need to use a special

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‫keyword return, followed by an expression of the correct type.

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‫So in this case it has to be a boolean expression so I could return true and then put semicolon on the

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‫end, or I could return false and then put a semicolon at the end.

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‫But it doesn't have to be that simple.

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‫It could actually be any expression.

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‫It could be another call to a function, it could be a variable, it could be a use of some operators

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‫as we have up here inside our statement.

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‫So, in fact, let's go ahead and try doing that.

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‫I'm going to take this expression.

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‫The distance moved and is is greater than mov distance.

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‫I'm going to cut it out and I'm going to put it as the return expression for this should platform return

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‫function.

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‫You notice it's going to complain here because distance move isn't a local variable within our should

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‫platform return function.

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‫So we're going to have to move some more things over.

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‫But before we do that, I don't want to forget to put a call to this should platform return in an if

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‫statement so should platform return and then remember to put the parentheses so the function actually

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‫gets called inside our F statement.

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‫So now it's starting to read a bit better to me.

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‫If platform should return, then we do all of the following.

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‫So now what we need to do is bring across the distance moved variable that we've got in MOVE platform.

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‫We don't actually need it inside MOVE platform.

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‫I'm going to cut it out and bring it and put it on the line before I return statement.

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‫Usually return statement is the last thing in a function because once you've returned out of a function,

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‫you actually don't do anything else.

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‫If I were to put something like a log message, so I'll put a you log after my return statement with

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‫some sort of message.

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‫Usually what's going to happen is you'll get a warning from your compiler saying that this line will

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‫never be reached and that you probably didn't mean to do that.

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‫So the return statement usually is the last thing.

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‫So having moved across the line that defines the distance moved in should platform return function,

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‫you can see it's now saying, hey, I don't have a current location and well the current location we

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‫can just very easily grab, we've set the current location just before we're calling should platform

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‫return.

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‫So actually get active location is exactly what we want.

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‫So I'm just going to put that instead of a variable, I'm just going to put a call to get active location

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‫in the place and should platform return.

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‫So now what we've got is the distance moved is equal to the of distance between the start location and

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‫the get active current location.

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‫So if that's greater than configured move distance, then yes, the platform should return.

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‫That's what this function is saying and it allows us to use it at a higher level of abstraction from

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‫within our MOVE platform function.

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‫Now you'll notice that it's now complaining that we can't get the distance move to print out overshoot.

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‫Well, that's no big deal.

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‫I don't actually want to print that anymore.

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‫It's kind of messing up my function anyway.

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‫So I'm going to delete the overshoot variable line.

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‫I'm going to delete the get name line, I'm going to delete the log message because it was only there

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‫temporarily, hence the log temp name.

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‫So now our move platform function is starting to look a lot cleaner.

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‫We can see that we are doing some updating of the location here.

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‫We can see whether the platform should return and if it should.

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‫Then we are updating the location and flipping it around.

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‫Now one thing that I think would look a little bit better here is if we had an alt statement instead

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‫of having this bunch of code at the top.

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‫So if the platform should return, we will execute this else we will execute the normal code in terms

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‫of moving it forward.

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‫So remember we cast your mind back to when we talked about the alt statement.

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‫It just comes after an if statement and we just do it like this.

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‫After the braces, we have a new line and type else, then another new line and open some new parentheses

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‫and we can just move this code that's up here at the top of our tick.

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‫We can take it and move it down into the alt statement.

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‫So now it seems pretty straightforward.

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‫Should the platform return then do the code that does platform returning else?

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‫We're moving the platform forward with our platform velocity.

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‫Now I'd like to challenge you to create your own function with a return value.

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‫I'd like you to add a get distance moved function.

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‫So we've currently calculate this into a variable called distance moved.

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‫I'd like you to replace that with a call to a function instead.

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‫So it should return a float because that's how the type of distance moved, we should call it in should

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‫platform return.

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‫So instead of using the vector dist, we should be using our own implementation.

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‫So what code should we should it contain?

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‫What code should we put into it with?

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‫The hint is that we've already typed this code, so you are just copying and pasting it into the new

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‫function.

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‫But have a little think about what the return expression should be, such that what we're returning

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‫is the distance moved value.

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‫Pause the video and have a go.

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‫Welcome back.

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‫So let's go over to our head of file.

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‫We'll add a new function here with a float return value called get distance moved.

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‫And then we're going to have no arguments in the parentheses.

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‫And then we're going to go over to our moving platform.

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‫CP We're going to add in a float, a moving platform, colon, colon distance moved or get distance

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‫moved, I should say parentheses.

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‫And then we'll put a new set of braces on the next line.

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‫And what we want to return is literally just the expression we're using to create our distance move

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‫float so I can cut that out and paste it in here.

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‫So it's f vector, colon, colon, dist, start location, get active location and put semicolon at

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‫the end of that line.

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‫And that means that in should platform return.

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‫Now instead of having this distance moved variable, I'm going to delete that line that's half completed.

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‫We're going to return get distance moved.

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‫Parentheses is greater than the move distance.

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‫So we've kind of taken what was going into a variable and pulled it out into its own function instead.

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‫And this means that whenever we want to refer to the distance moved, if we did want to have kept that

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‫log message in MOVE platform, then we can easily just call the function, get distance moved from any

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‫of the functions in our class.

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‫Great stuff.

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‫So in this lecture we've learned about return statements and return values, and we've used them to

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‫create two new functions in our class.

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‫I'll see you in the next lecture.