1，基类的指针指向派生类的对象，指向的是派生类中基类的部分。所以只能操作派生类中从基类中继承过来的数据和基类自身的数据。
2，C++的多态性可以解决基类指针不能操作派生类的数据成员的问题。
例子如下：
一，普通的基类的指针指向派生类的对象
#include <iostream>
using namespace std;
class Virtualbase
{
public:
void Demon(){ cout << "this is Virtualbase class" << endl; };
void Base() { cout << "this is farther class" << endl; };
};
class SubVirtual :public Virtualbase
{
public:
void Demon() {
cout << "this is SubVirtual!" << endl;
}
void Base() {
cout << "this is subclass Base" << endl;
}
};
void main()
{
Virtualbase* inst = new SubVirtual();
inst->Demon();
inst->Base();
system("pause");
return;
}
运行结果为：
this is Virtualbase class
this is farther class
二，C++的多态，基类的指针指向派生类的对象
#include <iostream>
using namespace std;
class Virtualbase
{
public:
virtual void Demon(){ cout << "this is Virtualbase class" << endl; };
virtual void Base() { cout << "this is farther class" << endl; };
};
class SubVirtual :public Virtualbase
{
public:
void Demon() {
cout << " this is SubVirtual!" << endl;
}
void Base() {
cout << "this is subclass Base" << endl;
}
};
void main()
{
Virtualbase* inst = new SubVirtual();
inst->Demon();
inst->Base();
system("pause");
return;
}
运行结果为：
this is SubVirtual!
his is subclass Base