上课铃响以后 //多态性

如本章开篇所述，当小学里的上课铃响之后，学生（Student）、教师（Teacher）和校长（Principal）会对同一个消息表现出不同的行为。请设计Person、Student、Teacher以及Principal类，合理安排他们之间的继承关系并将所有类的bellRing()及析构函数设计为虚函数，使得下述代码可以正常执行并产生期望的执行结果。

裁判测试程序样例：

 

#include <iostream>
using namespace std;

//定义Person, Student, Teacher, Principal类

int main() {
    cout << "School bell rings..." << endl;
    Person* persons[3] = {new Student(),new Teacher(),new Principal()};
    persons[0]->bellRing();
    persons[1]->bellRing();
    persons[2]->bellRing();
    for (auto i=0;i<3;i++)
        delete persons[i];
    return 0;
}

 

输入样例：

 

输出样例：

School bell rings...
I am a student learning in classroom.
I am a teacher teaching in classroom.
I am the principal inspecting in campus.
A student object destroyed.
A teacher object destroyed.
A principal object destroyed.

#include <iostream>
using namespace std;

//定义Person, Student, Teacher, Principal类

int main() {
    cout << "School bell rings..." << endl;
    Person* persons[3] = {new Student(),new Teacher(),new Principal()};
    persons[0]->bellRing();
    persons[1]->bellRing();
    persons[2]->bellRing();
    for (auto i=0;i<3;i++)
        delete persons[i];
    return 0;
}
 

 

class Person {
    public:
    virtual void bellRing()=0;
    virtual ~Person(){}
};
class Student:public Person{
    public:
    virtual void bellRing()
    {
        cout<<"I am a student learning in classroom."<<endl;
    }
    virtual ~Student(){cout<<"A student object destroyed."<<endl;}
};
class Teacher:public Person{
    public:
    virtual void bellRing()
    {
        cout<<"I am a teacher teaching in classroom."<<endl;
    }
    virtual ~Teacher(){cout<<"A teacher object destroyed."<<endl;}
};
class Principal:public Person{
    public:
    virtual void bellRing()
    {
        cout<<"I am the principal inspecting in campus."<<endl;
    }
    virtual ~Principal(){cout<<"A principal object destroyed."<<endl;}
};