リロードタイプ変換の演算子

/*
*            ：
*Copyright（c）2013，           
*All rights reserved.
*    ：
*  ：   
*    ：2014 4 29 
*   ：v0.1
*             ：
*    ： 
*    ：    Teacher(  )    Student(  ) ，    ，            。
*    ：
*    ：
*    ：
*    ：
*    ：
*/

#include <iostream>
#include <cstring>
using namespace std;
class Student
{
private:
    int num;
    char name[20];
    char sex;
    double score;
public:
    Student();
    int get_num()
    {
        return num;
    }
    char *get_name()
    {
        return name;
    }
    char get_sex()
    {
        return sex;
    }
    friend istream &operator>>(istream &,Student &);
    friend ostream &operator<<(ostream &,Student &);
};
class Teacher
{
private:
    int num;
    char name[20];
    char sex;
    int pay;
public:
    Teacher();
    Teacher(Student &);
    friend istream &operator>>(istream &,Teacher &);
    friend ostream &operator<<(ostream &,Teacher &);
};
Student::Student()
{
    int n;
    double sco;
    char nam[20],s;
    num=n;
    strcpy(name,nam);
    sex=s;
    score=sco;
}
istream &operator>>(istream &input,Student &stu)
{
    input>>stu.num>>stu.name>>stu.sex>>stu.score;
    return input;
}
ostream &operator<<(ostream &output,Student &stu)
{
    output<<"num:"<<stu.num<<"
name:"<<stu.name<<"
sex:"<<stu.sex<<"
score:"<<stu.score<<endl;
    return output;
}
Teacher::Teacher()
{
    int n,p;
    char nam[20],s;
    num=n;
    strcpy(name,nam);
    sex=s;
    pay=p;
}
Teacher::Teacher(Student &stud)
{
    num=stud.get_num();
    strcpy(name,stud.get_name());
    sex=stud.get_sex();
    pay=20000;
}
istream &operator>>(istream &input,Teacher &t)
{
    input>>t.num>>t.name>>t.sex>>t.pay;
    return input;
}
ostream &operator<<(ostream &output,Teacher &t)
{
    output<<"num:"<<t.num<<"
name:"<<t.name<<"
sex:"<<t.sex<<"
pay:"<<t.pay;
    return output;
}
int main()
{
    Teacher t1,t2;
    Student t3;
    cout<<"        "<<endl;
    cin>>t1;
    cout<<"      "<<endl;
    cout<<t1<<endl;
    cout<<"        "<<endl;
    cin>>t3;
    cout<<"      "<<endl;
    cout<<t3<<endl;
    t2=Teacher(t3);
    cout<<"            "<<endl;
    cout<<t2<<endl;
    return 0;
}