C++多态练习题
C++多态练习题
1．阅读下面的程序，写出程序运行的结果。
程序1：
#include <iostream>
using namespace std;
class Base
{public:
Base(int m){n=m++; }
virtual void g1(){cout<<"Base::g1()..."<<n<<endl; g4();}
virtualvoid g2(){cout<<"Base::g2()..."<<++n<<endl;g3();}
void g3(){cout<<"Base::g3()..."<<++n<<endl; g4();}
void g4(){cout<<"Base::g4()..."<<++n<<endl;}
protected:
int n;
};
class Derive:public Base
{public:
Derive(int n1,int n2):Base(n1){ j=n2;}
void g1(){cout<<"Deri::g1()..."<<++n<<endl;g2();}
void g3(){cout<<"Deri::g2()..."<<++n<<endl;g4();}
private:
int j;
};
int main(){
Derive Dobj(1,0);
Base Bobj=Dobj;
Bobj.g1();
cout<<"------------------"<<endl;
Base *bp=&Dobj;
bp->g1();
cout<<"------------------"<<endl;
Base &bref=Dobj;
bref.g1();
cout<<"------------------"<<endl;
Dobj.g1();
return 0;
}
程序2：
#include <iostream>
using namespace std;
class A
{public:
A(){cout<<"A::A() called.\n";}
virtual ~A(){cout<<"A::~A() called.\n";}
};
class B:public A
{public:
B(inti)
