Is it possible to put several objects together inside a union?

Question

What if I have this:

union{
    vector intVec ;
    vector floatVec ;
    vector doubleVec ;
} ;

Of cours

Answer 1

Current C++ standard does not allow non-POD types inside unions. You will get this compiler error from gcc:

error: member ‘std::vector >
::i’ with constructor not allowed in union
error: member ‘std::vector >
::i’ with destructor not allowed in union

New C++ standard (C++0x) proposes unrestricted unions, but it adds yet more object lifetime pitfalls to C++.