Memset Initialization Class error parsing when calling virtual functions

Occasionally in the group saw a piece of code problem, I knocked the next try to summarize; code:

#include <cstring>

#include <iostream>

Using namespace Std;class parent{public    :        Parent () {}        virtual void output ();}; void Parent::output () {    cout << "Parent" << Endl;} Class Son:public parent{public    :        virtual void output ();}; void Son::output () {    cout << "son"  << Endl;} int main () {    son s;    Memset (&s,0,sizeof (s));    Parent &p = s; The comment can be opened in error with the    Parent p;    P.output ();    S.output ();    return 0;}

The analysis is as follows:

There is usually no error when using memset for initialization, but if the internal structure is changed,  there is an error, and each class containing a virtual function has a pointer to the virtual table function, which is overwritten when memset. Therefore, the invocation of a virtual function bound by the runtime causes the program to crash if the call to bind does not run properly, so the constructor is initialized when there is a virtual function with the parent class reference to the subclass object;

Ubuntu Error Situation:

Memset Initialization Class error parsing when calling virtual functions