Constucting a struct variable in c++

I am not sure what you are asking, but I’ll give it a try.
Are you trying to define a new UStruct? Or you have one already?

If you are trying to define a ustruct then on on your .h file add a definition like so:

USTRUCT(BlueprintType)
struct FMyUStruct
{
    GENERATED_BODY()
    UPROPERTY()
    int32 MyInt;
}

then you will have to pass a variable like this to your function:

FMyStruct myStruct;
Func(myStruct);

but the definition must be as follows:

     UFUNCTION(BlueprintCallable)
     void Func( FMyStruct& Struct ); 
    // notice I am using a reference because 
    // pointers to structs are not supported in blueprint

Now, if the function is hardcoded and you already have the struct you should try to cast your pointer:

Cast<UStruct>(myStruct)

but I am not sure that would work. Also you can try a reinterpret_cast()