C++基础之友元

#include<iostream>
using namespace std;
class Student{
    private:
        int id;
        string name;
    public:
         Student(int id,string name);  
         //声明友元函数
         friend void show(Student &stu);     
};
//友元函数的实现（直接可以访问类的私有属性）
void show(Student &stu){
    cout<< stu.id << " name:" <<stu.name <<endl;
};
Student::Student(int id,string name):id(id),name(name){

}
int main(){
    Student stu(1,"张三");
    show(stu);
    return 0;
}

#include<iostream>
using namespace std;
class Teacher;
class Student{
    private:
        int id;
        string name;
    public:
         Student(int id,string name);
         void show(Teacher *tea);   
};
Student::Student(int id,string name):id(id),name(name){

}
class Teacher{
    private:
        int id;
        string name;
    public:
        Teacher(int id,string name);  
        //将Student类声明为Teacher类的友元类
        friend class Student;
};
Teacher::Teacher(int id,string name):id(id),name(name){

}
void Student::show(Teacher *tea){
    cout << this->id << this->name << tea->name << endl;
}

int main(){
    Teacher tea(1,"老外");
    Student stu(1,"张三");
    stu.show(&tea);
    return 0;
}