C++已经删除的函数

Question

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






class Date {
public:
    int year;
    int month;
    int day;






};


ostream& operator<<(ostream cout, Date &d) {
    cout << d.year << "年" << d.month << "月" << d.day << "日";

    return cout;

}



class  Person {
private:
    int id;
    string sex;
    Date date;
    string IDcard;

public:
    //构造函数
    Person(int id, string sex, Date date,string IDcard) {
        this->id = id;
        this->sex = sex;
        this->date = date;
        this->IDcard = IDcard;
     }

//复制构造函数
    Person(const Person  &p) {
        this->id = p.id;
        this->sex = p.sex;
        this->date = p.date;
        this->IDcard =p. IDcard;
}



    //内联成员函数
    inline void showPersom() {
        cout << "员工编号为" << id << endl;
        cout << "员工性别为" << sex << endl;
        cout << "员工的出生年月日为" << date << endl;
        cout << "员工的身份证号码为" << IDcard << endl;
    }

    //带默认形参的成员函数


    //析构函数
    ~Person() {

    }
};

在打印员工出生年月日的时候显示无法引用函数，是已经删除的函数
求求这是为什么啊

Answer 1

ostream& operator<<(ostream &cout, Date &d) {