C++ 虚拟方法

面试题中常见的C++ 虚拟方法： 

#include <iostream.h> 

class A 
{ 
public:
    virtual void print(void) 
    { 
        cout<<"A::print()"<<endl; 
    } 
};
class B:public A 
{ 
public:
    virtual void print(void) 
    { 
        cout<<"B::print()"<<endl;
    }; 
}; 
class C:public B
{
public:
    virtual void print(void)
    {
        cout<<"C::print()"<<endl;
    }
};
void print(A a) 
{ 
    a.print(); 
} 
void main(void) 
{ 
    A a, *pa,*pb,*pc; 
    B b; 
    C c; 

    pa=&a; 
    pb=&b; 
    pc=&c; 

    a.print(); 
    b.print(); 
    c.print(); 

    pa->print(); 
    pb->print(); 
    pc->print(); 

    print(a); 
    print(b); 
    print(c); 
}

 

执行结果：

A::print()
B::print()
C::print()
A::print()
B::print()
C::print()
A::print()
A::print()
A::print()