写好了一个关于People的类然后代码没错，这个是什么错了

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

class Date{
public:
    Date(char brithday[12])
{   cout<<"类内嵌子对象被调用"<<endl;
    cout<<"brithday is"<<brithday[12]<<endl;}
};
class People{
private:
       int number;
       char sex[4];
       char *id;
public:
    Date a(char a[12]);//类内嵌子对象
    People(int a,char s[4],char *i);
    void print();
    ~People();
};

    People::People(int a,char s[4],char *i)//定义了一个对象成员函数
    {   number=a;
        sex[4]=s[4];
        id=new char [strlen(i)+1];
        strcpy(id,i);
        cout<<"对象成员函数被调用"<<endl;
    }

    void People::print(){cout<<number<<sex[4]<<*id;}

    void main()
    {int b;//输入编号a的值
    char k[4];//性别sex
    char m[12];//brithday
    char l[20];//身份证ID
    cin>>b;
    cin>>k;
    cin>>l;
    cin>>m;
    People(b,k,l);

    Date::Date (m);
    }