Question

I’m trying to retrieve a boolean value from one of two member functions. I would like to call a member function(main) that will point to one of two member functions based on a value passed to main…here is what I have so far:

    class CRoutine{

    ...
    BOOL (*MainRoutine(BOOL opcode))();
    static BOOL SubRoutine1();
    static BOOL SubRoutine2();
    ...
    };

    BOOL (*CRoutine::MainRoutine(BOOL opcode))()
    {   
        switch ( opcode )
        {
        case false:
            MessageBox(NULL, L"Routine1", L"Routine1", MB_OK);
            return &CRoutine::SubRoutine1;
        case true:
            MessageBox(NULL, L"Routine2", L"Routine2", MB_OK);
            return &CRoutine::SubRoutine2;
        default:
            MessageBox(NULL, L"Default Routine Selected", L"Routine1", MB_OK);
            return &CRoutine::SubRoutine1;
        }
    }

    BOOL CRoutine::SubRoutine1()
    {
        MessageBox(NULL, L"Routine1", L"Routine1", MB_OK);
        return true;
    }
    BOOL CRoutine::SubRoutine2()
    {
        MessageBox(NULL, L"Routine2", L"Routine2", MB_OK);
        return false;
    }

    winMain(...)
    {
    ...
 m_routine = new CRoutine();
    BOOL result = m_routine->MainRoutine(0);
    ...
    }

My question is:

How do I call MainRoutine() in order to get the boolean value from SubRoutine1() or SubRoutine2(). When I run the program as is I get the following error:

error C2440: ‘initializing’ : cannot convert from ‘BOOL (__cdecl *)(void)’ to ‘BOOL’

This is mostly theory I’m interested in, I know there are other ways of getting such a simple answer…thanks in advance.

Answer 1

Like this:

BOOL result = m_routine->MainRoutine(0)();

It is because you return function pointer from MainRoutine(0), thus you need another pair of parentheses to invoke the function pointed by it.

---

By the way, you are returning plain function pointer, not a member function pointer.