C++ Must take either one or zero argument error (Operator+)

Question

I have the following statement in my Hour.cpp file: (after class Hour)

Hour Hour ::operator+(const Hour& h1, const Hour& h2) const{
    return Hour(h1.getHour()+ h2.getHour(), h1.getMinute() + h2.getMinute(), h1.getSecond() + h2.getSecond());
}

However, after running it I get:

error:  must take either zero or one argument

Answer 1

While overloading an operator as a member function, you can only another class as a second operand. The first operand is the object of the class itself. So, you have two options:

• You can modify the overloading function as

Hour Hour::operator+(const Hour& h) const{
    return Hour(hour_ + h.getHour(), minute_ + h.getMinute(), seconds_ + h.getSecond());
}

where hour_, minute_, seconds_ are member variables of Hour class.

• Do not implement as a member function

Hour operator+(const Hour& h1, const Hour& h2) const{
    return Hour(h1.getHour()+ h2.getHour(), h1.getMinute() + h2.getMinute(), h1.getSecond() + h2.getSecond());
}