How to store various types of function pointers together?

Question

Normal pointers can be stored using a generic void*. e.g.

void* arr[10];
arr[0] = pChar;
arr[1] = pINt;
arr[2] = pA;

Sometime

Answer 1

A pointer to a function can be converted to a pointer to a function of a different type with a reinterpret_cast. If you convert it back to the original type you are guaranteed to get the original value back so you can then use it to call the function. (ISO/IEC 14882:2003 5.2.10 [expr.reinterpret.cast] / 6)

You now only need to select an arbitrary function pointer type for your array. void(*)() is a common choice.

E.g.

int main()
{
    int a( int, double );
    void b( const char * );

    void (*array[])() = { reinterpret_cast(a)
                        , reinterpret_cast(b) };

    int test = reinterpret_cast< int(*)( int, double) >( array[0] )( 5, 0.5 );
    reinterpret_cast< void(*)( const char* ) >( array[1] )( "Hello, world!" );
}

Naturally, you've lost a lot of type safety and you will have undefined behavior if you call a function through a pointer to a function of a different type.