C++ 类再探

 1 #include <iostream>
 2 #include <typeinfo>
 3 #include <string>
 4 using namespace std;
 5 
 6 class Person {
 7     //设为友元，可访问类的非公有成员
 8     friend void read(istream &is, Person &p);
 9     friend void print(ostream &os, Person &p);
10 private:
11     string name;
12     string address;
13     mutable int count = 0;//突破界限之const函数改值
14 
15 public:
16     static string t;
17     Person() = default;
18     Person(string _name, string _address) {
19         name = _name;
20         address = _address;
21     }
22     string getName() const {
23         ++ count;//mutable 可变值
24         t = "blue"; //static 也可变
25         return this->name;
26     }
27     string getAddress() const {
28         return this->address;
29     }
30     int getCount() const {
31         return this->count;
32     }
33 };
34 
35 string Person::t = "yellow";
36 
37 //read the obj
38 void read(istream &is, Person &p)
39 {
40     is >> p.name >> p.address;
41 }
42 
43 //print the obj
44 void print(ostream &os, Person &p) 
45 {
46     os << p.name << " " << p.address;
47 }
48 
49 int main()
50 {
51     Person yoci("nan", "Shan‘an-Xi");
52     cout << yoci.getName() << endl;
53     cout << yoci.getAddress() << endl;
54     cout << yoci.getCount() << endl;
55     cout << Person::t << endl;
56 
57     return 0;
58 }