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‫Hello and welcome.

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‫In this lecture, we're going to be learning about how we can get outputs out of functions in C++.

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‫And we're going to use this to vastly simplify our code and to start implementing some of that pseudocode

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‫we've written.

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‫Let's dive in.

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‫So before we try to understand return values from functions, let's do a brief detour and understand

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‫it.

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‫Two concepts here add two more concepts to our glossary.

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‫So the first one is the expression and expression is a fragment of code that produces a value.

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‫And there's the statement which is a fragment of code that is an action to be performed.

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‫Now these two actually have a relationship in that an expression almost always is a statement in that

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‫to calculate the value of a fragment of code, you need to it needs to be an action to be performed.

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‫But the same isn't necessarily true the other way around.

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‫A statement isn't always going to give you a value.

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‫So let's have a look at some examples of expressions and some things that are not from the code that

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‫we've already written.

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‫So when we type my vector into C++, this is an expression because it has the value of whatever is stored

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‫inside the my vector variable.

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‫Same is true for local vector.

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‫And in fact if you have local vector plus z, that itself is an expression and local vector dot z plus

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‫100.

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‫That itself is an expression too, because the local vector z gave you the value inside of the Z member.

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‫And when you add 100, that gives you a new value which has the addition of 100.

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‫So these are all expressions.

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‫However, something that is not an expression is when we declared our local vector and we said F vector,

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‫local vector equals my vector and put a semicolon at the end of the line.

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‫We can't use that to get a value.

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‫There's no value there.

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‫It's just telling C++ that Here's an action for you to perform.

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‫I want you to create a new local vector.

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‫So that is not an expression.

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‫However, something that is an expression is get actor location.

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‫It's a function that we are calling because there's parentheses on the end here.

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‫We actually don't have any arguments here.

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‫This is an empty list of arguments, but it is calling something.

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‫And because this function has a return value, the actual piece of code here is an expression that takes

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‫on the value of whatever's returned from the function.

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‫And this is essentially the same as the output pins that we have previously seen in Blueprint.

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‫Except unlike with Blueprint, you can only have one output value from a function.

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‫There's just one return value.

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‫So that is what we can use over here where we've written our pseudo code that says Get current location.

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‫That is where we're going to do that.

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‫We're going to get the location using our get active location.

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‫So let's create a new local variable here.

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‫We're going to have a new local variable called F of type F vector.

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‫It has to be a type F vector because that is the type returned from get active location.

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‫And we're going to call this current location and we'll set that equal to the result or the expression

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‫get actor location and then parentheses a set of matching parentheses and then a semicolon to end the

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‫line.

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‫So if we dissect this line a little bit, we can see that this bit here, the get actor location and

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‫the parentheses is the expression it's getting us the value, which is the current location of the actor.

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‫Then we are doing an assignment to the current location, which is also being declared right here.

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‫So on this line, this whole line is not an expression.

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‫There's no value out of it, it is a statement.

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‫And usually you can tell a statement because in C++ it ends in a semicolon.

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‫Okay, so this is essentially going to allow us to do away with the my vector and local vectors that

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‫we've been using previously because we should just be able to update our local variable here, this

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‫current location that we've got from the location of our actor.

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‫So what we're going to do is further down here, we've got a comment that says, set the location.

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‫So after that comment line, I'm going to do a set actor location using the expression current location,

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‫which is just using that variable value and then put a semicolon at the end of the line to say that

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‫this whole thing is a statement.

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‫We want it to execute this action set at a location and notice that I while my comments are indented,

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‫I have decided not to indent the code to match because usually we want.

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‫Codes to be at one level of indentation within the function.

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‫Now what I can do is I can remove all of the code we had previously, everything involving local vector.

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‫My vector set a location using the local vector.

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‫I can remove all of that so that all we've got now is the stuff around our comments.

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‫And also I'm going to go over into the header file and clean things up a bit here.

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‫We no longer need the my vector, we no longer need the my x new properties.

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‫So I'm going to delete these ones as well.

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‫Now obviously the moving platform CP doesn't actually do very much because we get the current active

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‫location, then we set it again, which basically has no effect.

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‫So I'd like you to have a go at updating the current location of the moving platform in that tick function.

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‫So use the X or Y members as you see fit.

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‫One X will move you forward, Y will move you to the right, then you can add to it and assign back

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‫into the member, as we've been doing previously, to update our moving platforms location.

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‫So add one or two depending on how fast you want the platform to move and then the move the platform

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‫to its start location because now we don't have that member variable to tell it the start location,

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‫we actually using the current location.

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‫So wherever you place that platform, that is where the platform is going to start from.

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‫And then I'd like you to compile and test your code and see if it's moving, as you'd expect.

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‫Pause the video and have a go.

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‫Okay.

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‫Welcome back.

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‫So we're going to be placing this line of code just underneath the comment that talks about it, add

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‫vector to that location.

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‫And the reason we're putting it here is because of the order.

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‫We want to get the current location, update it and then set it.

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‫We don't want anything out of order to happen there.

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‫If we were to update it before we created the variable, well, that variable wouldn't exist.

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‫Remember, it's a local variable.

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‫It only exists once we create it within this particular call of the function.

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‫And if we'd done it after set actor location again, that modification would just be chucked away when

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‫we got to the closing brace in the function.

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‫So we're going to set the current location dot x, I'm going to use equal to the current location,

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‫dot x plus one and then put a semicolon at the end of the line.

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‫And we're going to go back in to Unreal and we're going to hit the compile button.

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‫And as I mentioned, we now need to go and move this moving platform to its starting location.

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‫So I'm going to click on our third person character and I'm going to copy his location by right clicking

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‫on the location, hitting copy, then going to our moving platform, right clicking on its location,

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‫hitting paste.

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‫So that puts the platform right inside our player, which is not actually what we want.

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‫So I'm going to move it slightly off to the right of the player like so and I can see if it's at the

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‫right height.

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‫I think I'll make it a little bit lower down, which is one of the benefits of using the current location

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‫rather than a location variable, is that I can actually see where this platform is going to be in the

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‫world.

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‫So now if I go ahead and hit play, then you can see that the platform is moving along nicely in the

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‫X direction and I can still jump on it and be moved along with it.

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‫Great stuff.

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‫Now we've learned how return values work out of functions.

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‫We are really starting to understand a lot of the concepts from blueprints in the C++ world.

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‫I'll see you in the next lecture.