虚函数列表： 取出方法 // 虚函数工作原理和(虚)继承类的内存占用大小计算 32位机器上 sizeof(void *) // 4byte

#include<iostream>  
using namespace std;  
  
class A  
{  
public:  
    virtual void fun1()  
    {  
        cout << "A::fun1()" << endl;  
    }  
    virtual void fun2()  
    {  
        cout << "A::fun2()" << endl;  
    }  
};  
  
class B : public A  
{  
public:  
    void fun1()  
    {  
        cout << "B::fun1()" << endl;  
    }  
    void fun2()  
    {  
        cout << "B::fun2()" << endl;  
    }  
};  
  
int main()  
{  
    A *pa = new B;  
    pa->fun1();  
    delete pa;  
  
    system("pause");   
    return 0;  
}  

class A  
{  
private:  
    int a;  
    int b;  
public:  
    virtual void fun0()  
    {  
        cout<<"A::fun0"<<endl;  
    }  
};  

class A     
{     
};    
  
class B     
{  
    char ch;     
    virtual void func0()  {  }   
};   
  
class C    
{  
    char ch1;  
    char ch2;  
    virtual void func()  {  }    
    virtual void func1()  {  }   
};  
  
class D: public A, public C  
{     
    int d;     
    virtual void func()  {  }   
    virtual void func1()  {  }  
};     
  
class E: public B, public C  
{     
    int e;     
    virtual void func0()  {  }   
    virtual void func1()  {  }  
};  
  
int main(void)  
{  
    cout<<"A="<<sizeof(A)<<endl;    //result=1  
    cout<<"B="<<sizeof(B)<<endl;    //result=8      
    cout<<"C="<<sizeof(C)<<endl;    //result=8  
    cout<<"D="<<sizeof(D)<<endl;    //result=12  
    cout<<"E="<<sizeof(E)<<endl;    //result=20  
    return 0;  
}  

class CommonBase  
{  
    int co;  
};  
  
class Base1: virtual public CommonBase  
{  
public:  
    virtual void print1() {  }  
    virtual void print2() {  }  
private:  
    int b1;  
};  
  
class Base2: virtual public CommonBase  
{  
public:  
    virtual void dump1() {  }  
    virtual void dump2() {  }  
private:  
    int b2;  
};  
  
class Derived: public Base1, public Base2  
{  
public:  
    void print2() {  }  
    void dump2() {  }  
private:  
    int d;  
};  

class Derived size(32):  
     +---  
     | +--- (base class Base1)  
 | | {vfptr}  
 | | {vbptr}  
 | | b1  
     | +---  
     | +--- (base class Base2)  
 | | {vfptr}  
 | | {vbptr}  
 | | b2  
    | +---  
 | d  
    +---  
    +--- (virtual base CommonBase)  
 | co  
    +---  

class A  
{  
public:  
    virtual void aa() {  }  
    virtual void aa2() {  }  
private:  
    char ch[3];  
};  
  
class B: virtual public A  
{  
public:  
    virtual void bb() {  }  
    virtual void bb2() {  }  
};  
  
int main(void)  
{  
    cout<<"A‘s size is "<<sizeof(A)<<endl;  
    cout<<"B‘s size is "<<sizeof(B)<<endl;  
    return 0;  
}  

#include<iostream>  
using namespace std;  
  
typedef void (*fVoid)();  
  
class A  
{  
public:  
    static void test()  
    {  
        printf("hello A\n");  
    }  
  
    fVoid print;  
  
    A()  
    {  
        print = A::test;  
    }  
};  
  
class B : public A  
{  
public:  
    static void test()  
    {  
        printf("hello B\n");  
    }  
  
    B()  
    {  
        print = B::test;  
    }  
};  
  
  
int main(void)  
{  
    A aa;  
    aa.print();  
  
    B b;  
    A* a = &b;  
    a->print();  
  
    return 0;  
}