ارور در union بی نام.

[Ananas]

به طور اتفاقی تو آدرس زیر خوندم که تو C++‎‎‎‎11 میشه از ساختمانی که سازنده داشته باشه تو union استفاده کرد :
http://en.wikipedia.org/wiki/C%2B%2B11


Unrestricted unions

In C++‎‎‎‎03, there are restrictions on what types of objects can be members of a union. For example, unions cannot contain any objects that define a non-trivial constructor. C++‎‎‎‎11 lifts some of these restrictions.[3]
This is a simple example of a union permitted in C++‎‎‎‎:

//for placement new

#include <new>



struct Point  {

    Point() {}

    Point(int x, int y): x_(x), y_(y) {}

    int x_, y_;

};

union U {

    int z;

    double w;

    Point p;  // Illegal in C++‎03; point has a non-trivial constructor.  However, this is legal in C++‎11.

    U() { new( &p ) Point(); } // No nontrivial member functions are implicitly defined for a union;

                               // if required they are instead deleted to force a manual definition.

};

The changes will not break any existing code since they only relax current rules.