What does the OUT parameter do?

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1

Hello,

in BuildingEscape, we use #define OUT, but what does this do? I don’t fully understand it yet.
What is the OUT parameter and why do we put it in front of some variables?
I searched on Google, but I could not find what I was looking for.

Thanks in advance.

2

It does absolutely nothing.

#define OUT

This is a macro, a simple text replacement. It will replace all uses of “OUT” in the file with nothing. Ben is using it as a comment that it’s an out parameter.

3

What does OUT normally do? Why is it necessary to #define OUT and make it do nothing?

4

There is no meaning. The definition is #define OUT

#define BILL BOB

Would replace all uses of BILL with BOB.

It’s not. Feel free to remove it.

5

If it doesnt do anything. Why are we then putting it in front of some variables?
Sorry for a lot of questions. (and Happy New Year in advance)

6

To comment that it’s an output parameter.

FHitResult HitResult;
FCollisionQueryParams TraceParameters(FName(TEXT("")), false, GetOwner());
GetWorld()->LineTraceSingleByObjectType(
		OUT HitResult,
		GetReachLineStart(),

HitResult is being given a value by the function. It’s an output parameter.
It would work the same without it. Alternatively you could add a prefix to the variable name or use a multiline comment.

7

Thanks for the help!

9

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