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‫Hello and welcome.

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‫In this lecture, we're going to be looking at vectors and in general more complicated things like structs

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‫in C++ and how we can access the individual parts to both set and get those from a struct.

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‫Let's dive in.

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‫So we've learned how to deal with basic data types in C++ and create variables and assign to them and

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‫even do some basic arithmetic with them.

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‫But what about if we wanted to deal with more complicated types such as vectors and transforms?

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‫Well, the process is actually very similar.

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‫Let's start off by clearing out some of the test code that we've already got.

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‫I'm going to delete all of my properties.

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‫For me, that's line 26 down to 51.

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‫And I'm also going to go over into the C++ file and delete lines 19 to 23, which is where I'm doing

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‫all of the work with those variables that I just deleted.

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‫So now Begin Play is completely empty and we're back to essentially square one.

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‫So now what I want to do is add in a new you property.

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‫So all caps again edit anywhere and I'm going to give this the type of F vector notice the capitalisation

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‫capital F, capital V and this is how we deal with the vectors that we've dealt with in Blueprint.

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‫They're the same vectors under the surface, but this is how we type it in C++.

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‫The F that precedes it just lets us know that this is a struct in the same way as the A that proceeds

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‫moving platform lets us know that that is an actor.

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‫That's not a C++ thing.

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‫That is an unreal naming convention for naming the different classes, structs and types.

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‫So then what we're going to do is give this variable a name and this works exactly the same way as if

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‫it were a float or an int.

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‫We can do call it my float, for example.

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‫It needs to have no spaces.

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‫And if we were to put semicolon at the end of the line here, then that's it.

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‫We've declared a new variable that will be visible in our details pane over in the editor, but that's

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‫not enough for me.

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‫I would like to actually give this a default value that's different from the default 000.

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‫To do that, we need to update our glossary with a new term.

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‫We need a constructor, which is essentially something in C++ that makes a new struct or class value.

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‫So if we were to create a constructor for the vector, the way this would work is we want to assign

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‫a value so we hit equals.

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‫And typically when we were dealing with integers or floats, we could just use something like a one

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‫or a true.

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‫There were built in values that allowed us to set the value of those basic types.

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‫But when we have more elaborate types like a struct, we need to use the constructor and the constructor

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‫will always have the same name as the data type.

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‫So it will be f vector spelled exactly the same, and then you open some parentheses and inside the

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‫parentheses you give the values that you want.

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‫So X, Y and Z is what makes up a vector.

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‫So we could have one, two and three all separated by commas, and then we close the parentheses and

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‫put semicolon at the end of the line.

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‫And that will give a default value of one, two and three in the X, Y and Z for this vector.

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‫Let's try it out.

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‫Go back into Unreal and hit the compile button.

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‫And once that's completed successfully, we can make sure we've got the moving platform actor selected

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‫in our outlier and have a look at the details pane and see that indeed we've got a new property called

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‫My Float.

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‫The other ones have been taken away and the values in its different positions X, Y and Z is one, two

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‫and three, just as we expect it.

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‫So that's great.

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‫But what if I wanted to get hold of these values and stick them perhaps in another property?

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‫So if I were to have another property which is marked as edit anywhere so we can see it in the inspector

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‫of type float called my x and we'll default this to zero just so that we can see that we're changing

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‫it.

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‫And what I want to do is grab the x value from the my float in begin play and I want to set it in the

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‫my x variable.

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‫So let's go over to the C++ file and in begin play after our the line that says super big in play,

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‫we're going to set my x equal to what we want to get something from my vector, but we don't want the

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‫whole of my vector.

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‫That would be an error.

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‫We can't set a vector into a float, we just want the x part of that vector.

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‫Well, to understand that, we need to understand the concept of an operator.

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‫Operators are symbols in C++ that do something.

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‫We've seen a few already.

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‫We've seen the plus operator, which adds two things together.

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‫There's also a minus operator.

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‫There's the equality operator, the equals operator, which assign.

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‫Things.

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‫So we're using this right here on line 19.

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‫That's an operator that is assigning the value of my vector to my X.

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‫And then we have one more operator, which we need to get to know which is the DOT operator.

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‫It is an operator that gets something from within a struct or class.

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‫So we want to get the X from within my vector.

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‫So we use a dot operator, we do dot x now we don't use a space here between the my vector and the x.

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‫We just leave these run together like so that's how we typically leave things even though it isn't necessarily

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‫an error to put spaces in.

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‫So we've got my vector x should get the x value of the vector and put it into the my x float.

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‫So we put semicolon at the end of the line there and as usual I'm ignoring the red squiggles because

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‫sometimes they take a long time to update and sometimes they aren't correct.

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‫And then we're going to go into live coding and hit the button that re compiles and just check whether

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‫we get a successful outcome.

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‫And no, you see, we've got a build failure.

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‫And if you look at the error, it's saying my vector is an undeclared identifier and that's because

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‫I've made a typo.

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‫I've called the F vector a my float and you're probably screaming at your screens, but it's good to

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‫show you that even experienced programmers make mistakes.

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‫We wanted to call that my vector, so I'm going to go back to the header file and rename it to my vector,

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‫which should remove the the problem with in my brain.

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‫Let's go ahead and click the compile button again.

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‫And that just gives you a taste of what it's like when you make errors, you get a compilation error.

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‫It happens all the time.

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‫In fact, it's very rare to to not make mistakes.

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‫The first time you do something, then we're going to go ahead and hit play and we'll see what value

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‫we get in the details pane.

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‫You can see now my x has been set to one because that was the value in the x component of the my vector

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‫variable.

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‫So I'd like to challenge you to set a vector value.

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‫We've been getting values from the vector.

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‫Now let's try setting them.

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‫Basically try using the dot operator to set a value.

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‫Try flipping the two sides of that equals so that we have the my X on the right and the my vector over

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‫on the left instead.

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‫And what if you change it over to Y or Z?

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‫Is there any difference there?

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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 I'm going to have a go at flipping these two around.

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‫Let's go over to the C++ and in Begin Play instead what I'm going to say is my vector dot y is equal

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‫to my x and then put semicolon at the end of the line.

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‫And this is how we can set values within a struct as well.

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‫So let's go back over into Unreal and recompile and then we can go ahead and set some value in my X.

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‫So I'm going to put the value of five in here.

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‫Then I'm going to go ahead and play and have a look at the details pane for the moving platform.

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‫And sure enough, the y value of my vector has been updated in begin play by the value in my x.

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‫So congratulations.

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‫We have seen how to use more complicated types that are compound types like structs in C++.

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‫I will see you in the next lecture.