C++ 继承函数

#include <iostream>
using namespace std;

class  passport
{
public:
    passport() //默认构造
    {
 　　
    }
    passport(int id,string tongxingzheng,string mima,string shenfen)
    {
        this->id = id;
        this->pass = tongxingzheng;
        this->password = mima;
        this->shenfenzheng = shenfen;
    }
    ~passport()//析构
    {
    }
 protected:
     //定义父类成员变量
    int  id;
    string pass;
    string password;
    string shenfenzheng;

};

class xiaoming :public passport  //子类继承父类passport的成员
{
public:
    xiaoming(int id, string tongxingzheng, string mima, string shenfen)
    {
        this->id = id;
        this->pass = tongxingzheng;
        this->password = mima;
        this->shenfenzheng = shenfen;
    }

};

int main()
{
    passport xiaoxiao(,"xiaoxiao", "", "");
    xiaoming xiaoqi(, "xiaoqi", "", "");
    return ;

}