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

From the C++ Standard, section 9.5:

An object of a class with a non-trivial constructor (12.1), a non-trivial copy constructor (12.8), a non-trivial destructor (12.4), or a non-trivial copy assignment operator (13.5.3, 12.8) cannot be a member of a union,

Here, for "non-trivial" read "useful" :-)