Functions with return values (C++)

Question

When main() calls a function which has a return value of some datatype ( primitive or user-defined ) , the statement in which the function is called is \'usually\' an assign

Answer 1

The return value is discarded; as you are not storing it anywhere.

One important advice:

Ideally the definition for operator + should look like.

complex complex::operator + (const complex& c)
{                            ^^^^^^^^^^^^^^
  complex add; 
  add.real = this->real + c.real;
  add.imag = this->imag + c.imag;
  return add;
}

In your original code 2 copies of complex are made; among which at least 1 can be avoided with above format where the argument is pass by const reference.

Also, in your code you should not change the current object; (otherwise it becomes like operator +=()). So create a temporary inside the function and pass it by value.