#include <iostream>
using namespace std;
class A
{
public:
virtual void Func1()
{
cout << "class A Func1" << endl;
}
virtual void Func2()
{
cout << "class A Func2" << endl;
}
};
class B
{
public:
virtual void Func1()
{
cout << "class B Func1" << endl;
}
void Func2()
{
cout << "class B Func2" << endl;
}
virtual void Func3()
{
cout << "class B Func3" << endl;
}
};
int _tmain(int argc, _TCHAR* argv[])
{
A *pa = new A;
B *pb = new B;
//交換AB虛函數表指針
int v_ptr = *((int*)pa);
*((int*)pa) = *((int*)pb);
*((int*)pb) = v_ptr;
pa->Func1();
pa->Func2();
pb->Func1();
pb->Func2();
pb->Func3();
return 0;
}
輸出結果:
class B Func1
class B Func3
class A Func1
class B Func2
class A Func2
通過輸出結果可以看出,編譯器爲每一個虛函數建立了一個索引項。如當pa->Func1();執行時,直接調用第0項對應的函數地址即可。