C++ Pre-fix and Post-fix operator overloading for addition (+) (not ++ or --)

Question

I am writing a Complex class for an assignment in which one of the methods should overload the default addition operator when adding a double to the complex number. So far, I have the following code which correctly works for c+5 where c is some Complex object

Complex& Complex::operator+(const double& d) const
{
    return Complex(real + d, imag);
}

However, it doesn't like it when I do 5+c. I think it might be because of a prefix post-fix thing but I am not sure.

My question is if there is a way to also overload the + operator so that I can do something like 5+c. I tried searching for a solution online but the only answers I could find dealt with the increment/decrement operators where you just add an int argument for the post-fix. I tried the same thing for + but it doesn't work.

Thank you very much.

Make it a free-standing operator (define outside if the class, if you need to, make it a `friend`). — stefan, Mar 16 '15 at 22:59
In the linked duplicate, scroll down to "Binary arithmetic operators" — M.M, Mar 16 '15 at 23:01

score 2 · Accepted Answer · answered Mar 16 '15 at 22:59

2

Two options come to mind:

1) Implement two non member functions:

Complex operator+(const Complex& lhs, double rhs);
Complex operator+(double lhs, const Complex& rhs);

2) Make Complex implicitly constructable from double (if it isn't already), and implement a single non-menber:

Complex operator+(const Complex& lhs, const Complex& rhs);

answered Mar 16 '15 at 22:59

juanchopanza

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I see. Is there no member function option? Thank you very much by the way – sshashank124 Mar 16 '15 at 23:00
@sshashank124 Not really, because a member has an implicit first parameter of type `Complex`. – juanchopanza Mar 16 '15 at 23:01

C++ Pre-fix and Post-fix operator overloading for addition (+) (not ++ or --)

1 Answers1