How to call an operator as function in C++

Question

I want to call a specific operator of specific base class of some class. For simple functions it\'s easy: I just write SpecificBaseClass::function( args );. How sho

Answer 1

The syntax of specifying a function as

::

is used when Method() is a static method in Class. If Method() is a instance method, then the invocation is on a class object.

Class classObject;
classObject.Method()

In this particular case, the declaration and usage of the operator+() method does not match.

So, one approach would be to make the operator+() method static. But, I think, operator methods can only be non-static member function or non-member function.

With all these knowledge, here is a full illustrative program.

#include 

struct B {
    int num_;

    B(int num) : num_( num ) {
    }

    static B add( const B & b1, const B & b2 ) {
        return B( b1.num_ + b2.num_ );
    }

    B operator+( const B & rhs ) {
        return B( num_ + rhs.num_ );
    }
};

int main() {
    B a(2), b(3);

    B c = B::add( a, b );
    assert( c.num_ == 5 );

    B d = a + b;
    assert( d.num_ == 5 );
}

The add() function is for example only, don't do it though.