拷贝构造函数问题

#include<iostream>
#include<stdlib.h>
using namespace std;
class date
{
private:
    int year;
    int month;
    int day;
public:
    date()
    {
        year=0;month=0;day=0;     
    }
    inline void birth()
    {
        cout<<"the birthday"<<endl;
        cout<<"please input the year:";
        cin>>year;
        cout<<"please input the month:";
        cin>>month;
        cout<<"please input the day:";
        cin>>day;
    }
    inline void print2()
    {
        cout<<year<<"."<<month<<"."<<day<<endl;
    }
    ~date()
    {}
};
class people
{
private:
    long int number;
    char sex;
    char id[20];
public:
    date b1;
    people()
    {
            number=0;sex='\0';
    }
    inline void xinxi()
    {
            cout<<"please input the number:";
            cin>>number;
            cout<<"please input the sex:(m/f)";
            cin>>sex;
            cout<<"please input the id:";
            cin>>id;
            b1.birth();
    }
    inline void print1()
    {
        cout<<number<<endl
            <<sex<<endl
            <<id<<endl;
        b1.print2();
    }
    ~people()
    {}
};
int main()
{
    int i,n;
    system("color 9e");
    people p1[1000];
    cout<<"How many people?";
    cin>>n;
    for(i=0;i<n;i++)
    {
        p1[i].xinxi();
    }
    for(i=0;i<n;i++)
    {
        p1[i].print1();
    }
    return 0;
}
怎样加拷贝构造函数