how to declare type conversion in header file and implement in cpp file?

Question

it doesn't work for me.
i have a header file and a cpp file.
need to define a conversion operator from my class to INT, but it gives me "syntax error" when declaring it in the H file and implementing in the cpp file. maybe i got the syntax wrong? in the H file i have in "public":

operator int();

and in the cpp file i have:

A::operator int() { return mNumber ;}

if i implement the function in the H file it works, but i don't want to do that.
can anyone help?

Answer 1

I also wanted to separate the class declaration from the implementation. The critical missing ingredient was the const:

// Foobar.hpp
class Foobar
{
    public:
        Foobar() : _v(42) {}

        operator int() const;

    private:

        int _v;
};

And then in the implementation file:

#include "Foobar.hpp"

Foobar::operator int() const
{
    return _v;
}

See this reference