How to avoid the copy when I return

Question

I have a function which returns a vector or set:

set foo() {
    set bar;
    // create and massage bar
    return bar;
}

set

        

Answer 1

I usually work around this by having function signature as

void foo(set *x)

Just pass it by reference or the other option is already mentioned in the comment.

Edit: I have changed the argument type to illustrate that x could be changed.

      set s;
      foo(&s);

This is only preferred when you have an old compiler. I suppose that could be the case with some of the projects.

And, better thing to do will be Either to use move semantics with c++11. Or go ahead returning the container and look into RVO in modern compilers.