学校的构成（I）

Description

学校是老师和学生组成的。现在定义Student、Teacher和School三个类来模拟一个学校。
Student类只有一个int类型的数据成员，表示学生的年级；Teacher类只有一个double类型的数据成员，表示该教师的工资；School类是由1个Student类的对象、1个Teacher类的对象组合而成。定义它们的构造函数和析构函数，使程序能产生样例所示的输出。

Input

输入4行，第1行和第3行是2个int类型的正整数；第2行和第4行是double类型的正数。

Output

见样例。

Sample Input

3
1600.31
4
2451.34

Sample Output

A student grade 3 is created.
A teacher with salary 1600.31 is created.
A school is created.
A student grade 4 is created.
A teacher with salary 2451.34 is created.
A student grade 4 is created.
A teacher with salary 2451.34 is created.
A school is created.
A school is erased.
A teacher with salary 2451.34 is erased.
A student grade 4 is erased.
A teacher with salary 2451.34 is erased.
A student grade 4 is erased.
A school is erased.
A teacher with salary 1600.31 is erased.
A student grade 3 is erased.

题目给定程序

int main()
{
    
    
    int g;
    double s;
    cin>>g>>s;
    School sch(g, s);
    cin>>g;
    Student stu(g);
    cin>>s;
    Teacher tea(s);
    School(g, s);
    return 0;
}

code：

#include<iostream>

using namespace std;

class Student{
    
    
	int grade;
public:
	Student(int nn){
    
    
		grade=nn;
		cout<<"A student grade "<<grade<<" is created."<<endl;
	}
	~Student(){
    
    
		cout<<"A student grade "<<grade<<" is erased."<<endl;
	}
};

class Teacher{
    
    
	double salary;
public:
	Teacher(double ss){
    
    
		salary=ss;
		cout<<"A teacher with salary "<<salary<<" is created."<<endl;
	}
	
	~Teacher(){
    
    
		cout<<"A teacher with salary "<<salary<<" is erased."<<endl;
	}
};

class School{
    
    
	Student stu;
	Teacher teac;
public:
	School(int g,double s):stu(g),teac(s){
    
    
		cout<<"A school is created."<<endl;
	}
	
	~School(){
    
    
		cout<<"A school is erased."<<endl;
	}
};

int main()
{
    
    
    int g;
    double s;
    cin>>g>>s;
    School sch(g, s);
    cin>>g;
    Student stu(g);
    cin>>s;
    Teacher tea(s);
    School(g, s);
    return 0;
}