using namespace std;
class A
{
public:
inline virtual void vfun()
{
cout << "this is vfun in class A" << endl;
}
};
class B : public A
{
public:
inline void vfun()
{
cout << "this is vfun in class B" << endl;
}
};
void test(void)
{
A* p;
A P;
// 由于A中声明了虚函数，那么在定义对象P时，P中将包含A类的vfptr，该vfptr指向A类的虚函数表，
p = &P;
// 因此下面的语句向显示”this is vfun in class A”
p->vfun();
B* q;
// 由于A中声明了虚函数，类B继承了A，那么在定义对象Q时，Q中将包含B类的vfptr，该vfptr指向B类的
// 虚函数表
B Q;
q = &Q;
p = q;
// p 现在是类B对象的一个指针，即Q的地址，而Q中包含了指向B类虚函数表的vfptr指针。因此下面的语句将显示
// “this is vfun in class B”
p->vfun();
}
/**********************
该函数运行结果：
this is vfun in class A
this is vfun in class B
************************/
class Parent
{
public:
int parent;
inline Parent(){}
inline Parent(int parent) { this->parent = parent; }
inline int return_parent(){return parent;}
inline virtual int Return() { return parent; }
inline virtual void haveFun() { cout << "haveFun in Parent" << endl; }
};
class Child : public Parent
{
public:
int child;
inline Child(){}
inline Child(int child) : Parent(child-25) { this->child = child; }
inline int Return() { return child ; }
inline void haveFun() { cout << "haveFun in Child" << endl; }
};
int main(void)
{
Parent* p = new Child(1991);
p->haveFun();
cout<<"p->return_parent() is :"<<p->return_parent()<<'\n';
//假如Parent 类Return()不声明为虚函数，则下边语句输出1966
//Parent 类Return()声明为虚函数，则下边语句输出1991
cout<<"p->Return() is :"<<p->Return()<<'\n';
return 0;
}
/**************************
运行结果：
haveFun in Child
p->return_parent() is :1966
p->Return() is :1991
Process returned 0 (0x0) execution time : 0.016 s
Press any key to continue.
***************************/
#include <iostream>
using namespace std;
class A
{
public:
inline virtual void vfun()
{
cout << "this is vfun in class A" << endl;
}
};
class B : public A
{
public:
inline void vfun()
{
cout << "this is vfun in class B" << endl;
}
};
void test(void)
{
A* p;
A P;
// 由于A中声明了虚函数，那么在定义对象P时，P中将包含A类的vfptr，该vfptr指向A类的虚函数表，
p = &P;
// 因此下面的语句向显示”this is vfun in class A”
p->vfun();
B* q;
// 由于A中声明了虚函数，类B继承了A，那么在定义对象Q时，Q中将包含B类的vfptr，该vfptr指向B类的
// 虚函数表
B Q;
q = &Q;
p = q;
// p 现在是类B对象的一个指针，即Q的地址，而Q中包含了指向B类虚函数表的vfptr指针。因此下面的语句将显示
// “this is vfun in class B”
p->vfun();
}
/**********************
该函数运行结果：
this is vfun in class A
this is vfun in class B
************************/
class Parent
{
public:
int parent;
inline Parent(){}
inline Parent(int parent) { this->parent = parent; }
inline int return_parent(){return parent;}
inline virtual int Return() { return parent; }
inline virtual void haveFun() { cout << "haveFun in Parent" << endl; }
};
class Child : public Parent
{
public:
int child;
inline Child(){}
inline Child(int child) : Parent(child-25) { this->child = child; }
inline int Return() { return child ; }
inline void haveFun() { cout << "haveFun in Child" << endl; }
};
int main(void)
{
Parent* p = new Child(1991);
p->haveFun();
cout<<"p->return_parent() is :"<<p->return_parent()<<'\n';
//假如Parent 类Return()不声明为虚函数，则下边语句输出1966
//Parent 类Return()声明为虚函数，则下边语句输出1991
cout<<"p->Return() is :"<<p->Return()<<'\n';
return 0;
}
/**************************
运行结果：
haveFun in Child
p->return_parent() is :1966
p->Return() is :1991
Process returned 0 (0x0) execution time : 0.016 s
Press any key to continue.
***************************/