Question

I was reading a document on operator overloading: http://courses.cms.caltech.edu/cs11/material/cpp/donnie/cpp-ops.html however when I run the code below (in an actual context) I always get a warning on how result is a local variable. And it makes sense that I shouldn’t be returning a local variable, but it seems to work fine. Is there a way to eliminate the warning with code like the following:

const Matrix & Matrix::operator+(const Matrix &other) const
{
  Matrix result(*this);
  result += other;
  return result;
}

The example on caltech’s website like this, is on the bottom of the link

Answer 1

To remove the warning, you need to return the Matrix by value.

You should also ideally define it as a free function since semantically it should not need to modify the object it is called on.