Union in c++ are they feasible

Question

Can a union in C++ have a member function? How do union with data members and member functions exist if an object is created?

If I suppose yes, then are they feasible an

Answer 1

I just added some more things to @maraguida example. I wrote it as a response just to heve more room. It illustrates that not only member functions, but also static member functions and operators can be added.

#include    

union x
 {
    int     t;
    float   f;

    int k( )        { return t * 42;};
    static int static_k( )  { return 42;};

    float k_f( )    { return f * 42.0f;};

    unsigned char operator []( unsigned int );
};

unsigned char x::operator []( unsigned int i )
{
    if ( i >= sizeof( x ) )
        return  0;

    return  ( ( unsigned char * )&t )[ i ];
}

int main( )
{
    x   y;
    y.t = x::static_k( );

    std::cout << "y.t\t= " << y.t << std::endl;
    std::cout << "y.f\t= " << y.f << std::endl;
    std::cout << "y.k( )\t= " << y.k( ) << std::endl;
    std::cout << "x::static_k( )\t= " << x::static_k( ) << std::endl;
    std::cout << "y.k_f( )\t= " << y.k_f( ) << std::endl;

    std::cout << "y[ 0 ]\t= " << ( unsigned int )y[ 0 ] << std::endl;
    std::cout << "y[ 1 ]\t= " << ( unsigned int )y[ 1 ] << std::endl;
    std::cout << "y[ 2 ]\t= " << ( unsigned int )y[ 2 ] << std::endl;
    std::cout << "y[ 3 ]\t= " << ( unsigned int )y[ 3 ] << std::endl;
}

It can be compiled with: g++ -Wall union_func.cpp -o union_func

The output is:

$ ./union_func 
y.t     = 42
y.f     = 5.88545e-44
y.k( )  = 1764
x::static_k( )  = 42
y.k_f( )        = 2.47189e-42
y[ 0 ]  = 42
y[ 1 ]  = 0
y[ 2 ]  = 0
y[ 3 ]  = 0

You can, for example, put a conversion operator to another type of your need, if it make sense to your need.