C++11 Visitor Mode

#include <iostream>#include<string>#include<string.h>#include<memory>#include<thread>#include<Windows.h>#include<future>using namespacestd;template<typename ... Types>structvisitor;template<typename T, TypeName ... Types>structVisitor<t, types...>: visitor<types...>{    usingVisitor<types...>:: Visit; Virtual voidVisit (Constt&) =0;}; Template<typename t>structVisitor<t>{    Virtual voidVisit (Constt&) =0;};structStA;structStB;structbase{typedef Visitor<sta, stb>Myvisitor; Virtual voidAccept (myvisitor&) =0;};structsta:base{DoubleVal; voidAccept (base::myvisitor&v) {v.visit (* This); }};structstb:base{DoubleVal; voidAccept (base::myvisitor&v) {v.visit (* This); }};structprintvisitor:base::myvisitor{voidVisit (Conststa&a) {cout<<"From StA:"<< A.val <<Endl; }    voidVisit (Conststb&b) {cout<<"From StB:"<< B.val <<Endl; }};intMain () {Printvisitor vis;    StA A; A.val=8.97;    StB b; B.val=8; Base*Base= &A; Base-Accept (VIS); Base= &b; Base-Accept (VIS);    GetChar (); return 0;}

C++11 Visitor Mode