#include <iostream>

 #include <typeinfo>

 #include <string>

 using namespace std;

 class Person {

     //设为友元，可访问类的非公有成员

     friend void read(istream &is, Person &p);

     friend void print(ostream &os, Person &p);

 private:

     string name;

     string address;

     mutable int count = ;//突破界限之const函数改值

 public:

     static string t;

     Person() = default;

     Person(string _name, string _address) {

         name = _name;

         address = _address;

     }

     string getName() const {

         ++ count;//mutable 可变值

         t = "blue"; //static 也可变

         return this->name;

     }

     string getAddress() const {

         return this->address;

     }

     int getCount() const {

         return this->count;

     }

 };

 string Person::t = "yellow";

 //read the obj

 void read(istream &is, Person &p)

 {

     is >> p.name >> p.address;

 }

 //print the obj

 void print(ostream &os, Person &p)

 {

     os << p.name << " " << p.address;

 }

 int main()

 {

     Person yoci("nan", "Shan'an-Xi");

     cout << yoci.getName() << endl;

     cout << yoci.getAddress() << endl;

     cout << yoci.getCount() << endl;

     cout << Person::t << endl;

     return ;

 }