关于C++友元类的实现讲解

#include 
#include 
using namespace std ;
//声明教师类 
class Techer ;
//学生类 
class Student 
{
 private:
 string name ;
 int age ; 
 char sex ; 
 int score ; 
 public :
 Student(string name , int age , char sex , int score);
 void stu_print(Techer &tech);
};
//教师类 
class Techer
{
 private:
 string name ;
 int age ; 
 char sex ; 
 int score ; 
 public :
 Techer(string name , int age , char sex , int score);
 //声明一个友元类
 friend Student ;
};
//Student类的构造函数的实现 
Student::Student(string name , int age , char sex , int score)
{
 this->name = name ; 
 this->age = age ; 
 this->sex = sex ; 
 this->score = score ;
}
//Techer类的构造函数的实现
Techer::Techer(string name , int age , char sex , int score)
{
 this->name = name ; 
 this->age = age ; 
 this->sex = sex ; 
 this->score = score ;
}
//打印Student类中的私有成员和Techer的私有成员 
void Student::stu_print(Techer &tech)
{
 //用this指针访问本类的成员 
 cout <name <age <sex <score <