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How to have a struct with reference to int?

Development Discussion C++ Programming
#1

I want to have a struct which has a reference to an int32, so that the actual int32 variable (no matter where it came from in the code) can be altered, not a copy of it. Since you cannot use pointers with int32 (it would be great if you could, because that would immediately solve the problem), I need to use a reference. But I cannot figure out how to set this up, in terms of initialisation.

The basic struct looks like this:


USTRUCT(BlueprintType)
struct FReferenceInt
{
    GENERATED_USTRUCT_BODY()

    UPROPERTY(VisibleAnywhere, BlueprintReadOnly)
    int32& IntReference;

    int32 TempValue = 0;

    FReferenceInt()
    {
        IntReference = TempValue;
    }

    FReferenceInt(int32 IntRef) : IntReference(IntRef) {};
}

When I create the struct I want to pass an int32 into it as a reference. The above won’t compile, and I don’t know how to get it working. I put the TempValue in there because it needs a default constructor, but the default constructor complains “there is no initializer for reference member IntReference”.

How can I have a reference to an int32 in a struct, such that I can manipulate the actual int32 from within the struct?

#2

You can use pointers with int32, but the problem is you can’t use it with blueprints (which don’t have the best pointer support) - also you could run into issues where you are pointing at an integer in some object that gets cleaned up (so now you’re pointing to junk, or worse - invalid memory ).

I would rethink your approach to whatever you are trying to do here.

#3

Ah, OK thanks!

I think you’re right that there’s a better way to accomplish what I’m doing.