一个带有以类对象为成员的类怎么重载<<才能显示对象成员的信息?

Question

我分别在person与student类中都以友元函数重载了<< 期望看到的结果是当进行到cout<<stu.teacher时自动调用person类中的<<重载函数,可是却显示<<不能作用于person类(VS报的)，而单独调用却可以。

想请问问什么会出现这种错误以及如何补救。

#include<iostream>
using namespace std;
class person {
    string name;
public:
    person(string n) :name(n) {};
    friend ostream& operator<<(ostream& os, person& per);
};
class student :public person {
    person teacher;
    int score;
public:
    student(string n, string n_teacher, int s) 
        :person(n), teacher(n_teacher), score(s) {};
    
    friend ostream& operator<<(ostream& os, student& stu);
};
ostream& operator<<(ostream& os, person& per)
{
    os<< "name:" << per.name << endl;
    return os;
}

ostream& operator<<(ostream& os, student& stu)
{
    os << "the student:" << endl;
    os << stu.name;//父类私有成员对子类不可见，此语句也无法实现。
    os << "score:" << stu.score << endl;
    os >> stu.teacher;//我明明在person类里定义了友元函数重载<<了，可这里还是不对。
    return os;
}
int main()
{
    student s1("Zhang San", "Li Si", 98);
    cout << s1;//不可行
    person p1("ff");//可行
    cout << p1;
    return 0;
}

Answer 1

• 帮你找了个相似的问题, 你可以看下: https://ask.csdn.net/questions/7808892