继承与组合

/*
*Copyright (c) 2014 ,烟台大学计算机学院
*All rights reserved.
*作者：张凤宁
*完成日期：2014年8月5
*版本号：v1.0
*问题描述：
*样例输入：
*样例输出：
*问题分析：用简单的方法，学会活学活用
*/
#include <iostream>
#include <string>
using namespace std;
class BirthDate
{
public:
    BirthDate(int,int,int);
    void display();
    void setbirthday(int,int,int);
private:
    int year;
    int month;
    int day;
};
class Teacher
{
public:
    Teacher(int,string,char);
    void display();
private:
    int num;
    string name;
    char sex;
};
class Professor:public Teacher
{
public:
    Professor(int,string,char,BirthDate);
    void display();
    void setbirthday(int,int,int);
private:
    BirthDate birthday;
};
BirthDate::BirthDate(int=0,int=0,int=0) {}
void BirthDate::display()
{
    cout<<"birthday:"<<year<<"/"<<month<<"/"<<day<<endl;
}
void BirthDate::setbirthday(int y,int m,int d)
{
    year=y;
    month=m;
    day=d;
}
Teacher::Teacher(int n,string nam,char s):num(n),name(nam),sex(s) {}
void Teacher::display()
{
    cout<<"num:"<<num<<endl;
    cout<<"name:"<<name<<endl;
    cout<<"sex:"<<sex<<endl;
}
Professor::Professor(int n1,string nam1,char s1,BirthDate birth):Teacher(n1,nam1,s1),birthday(birth) {}
void Professor::display()
{
    Teacher::display();
    birthday.display();
}
void Professor::setbirthday(int y,int m,int d)
{
    birthday.setbirthday(y,m,d);
}
int main()
{
    int num;
    string name;
    char sex;
    int year,month,day;
    cin>>num>>name>>sex;
    cin>>year>>month>>day;
    Professor prof(num,name,sex,BirthDate(year,month,day));
    cin>>year>>month>>day;
    prof.setbirthday(year,month,day);
    prof.display();
    return 0;
}