关于c++类的问题

#include<string>
#include<iostream>
using namespace std;

class people{
public:
    People(){
        number=0;
        sex=m;
    }
    void input();
    void output();
private:
    int number;
    char sex;
    Date birthday;
    string name;
};
void People::input(int num,a,b,c,char se,string nam,Date birthday){
    cout<<"请输入人员姓名:";
    cin>>name;
    cout<<"请输入人员性别:";
    cin>>se;
    cout<<"请输入人员编号:";
    cin>>num;
    cout<<"请输入录入人员时间:";
    cin>>a>>b>>c;
    number=num;
    sex=se;
    name=nam;
    birthday.setDate(a,b,c);
}
void People::output(){
    cout<<"姓名:"<<name<<"\n";
    cout<<"性别:"<<sex<<"\n";
    cout<<"编号:"<<number<<"\n";
    cout<<"录入时间:"<<birthday.getYear<<"年"<<birthday.getMonth<<"月"<<birthday.getDay<<"日"<<endl;
}

class Date(){
public:
    void setDate();
    int getYear();
    int getMonth();
    int getDay();
private:
    int year,month,day;
};
void Date::setDate(int a,int b,int c){
    year=a;
    month=b;
    day=c;
}
int Date::getYear(){
    return year;
}
int Date::getMonth(){
    return month;
}
int Date::getDay(){
    return day;
}

int main(){
    People langpeople;
    Date birthday;
    langpeople.input(int num,a,b,c,char se,string nam,Date birthday);
    langpeople.output();
    return 0;
}