C++基础类知识

默认构造，析构
拷贝构造，移动构造
拷贝赋值，移动赋值
取值
右值引用
其它
基类的析构函数应使用virtual 关键字，保证子类的析构函数能够被正常调用
作为接口类，如果不是基类，应该用final关键字
  1 // g++ testClass.cc -g -std=c++11 && ./a.out
  2 #include <iostream>
  3 #include <string.h>
  4 using namespace std;
  5 
  6 class MyStr final
  7 {
  8 private:
  9     char *name = NULL;
 10     int id;
 11     inline void MyStrncpy(char *dst, const char *src, size_t len) {
 12         if (dst != src) {
 13             strncpy(dst, src, len);
 14             dst[len] = '';
 15         }
 16     }
 17     inline void Reset() {
 18         id = 0;
 19         if (name) { 
 20             delete[] name; 
 21             name = NULL;
 22         }
 23     }
 24     inline void Clear() {
 25         id = 0;
 26         name = NULL;
 27     }
 28     inline void DeepCopy(const MyStr &other) {
 29         id = other.id;
 30         name = new char[strlen(other.name) + 1];
 31         MyStrncpy(name, other.name, strlen(other.name));        
 32     }
 33     inline void ShallowCopy(const MyStr &other) {
 34         id = other.id;
 35         name = other.name;      
 36     }
 37 public:
 38     // 默认构造函数
 39     explicit MyStr():id(0),name(NULL) {
 40         cout << "构造: " << __func__ << endl;
 41     }
 42     // 构造函数
 43     explicit MyStr(int _id, char *_name) {
 44         cout << "普通构造： " << __func__ << endl;
 45         id = _id;
 46         name = new char[strlen(_name) + 1];
 47         MyStrncpy(name, _name, strlen(_name));
 48     }
 49     // 析构函数
 50     ~MyStr() {
 51         cout << "析构： " << __func__ << endl;
 52         Reset();
 53     }
 54     // 拷贝构造
 55     MyStr(const MyStr& other) {
 56         cout << "拷贝构造： " << __func__ << endl;
 57         DeepCopy(other);
 58     }
 59     // 移动构造
 60     MyStr(MyStr &&other) {
 61         cout << "移动构造： " << __func__ << endl;
 62         ShallowCopy(other);
 63         other.Clear();
 64     }
 65     // 拷贝赋值， rhs means right hand side value
 66     MyStr &operator=(const MyStr &rhs) {
 67         cout << "拷贝赋值： " << __func__ << endl;
 68         if (this != &rhs) {
 69             Reset();
 70             DeepCopy(rhs);
 71         }
 72         return *this;
 73     }
 74     // 移动赋值
 75     MyStr &operator=(MyStr &&rhs) {
 76         cout << "移动赋值： " << __func__ << endl;
 77         if (this != &rhs) {
 78             Reset();
 79             ShallowCopy(rhs);
 80             rhs.Clear();
 81         }
 82         return *this;
 83     }
 84 };
 85 
 86 int main()
 87 {
 88     cout << "普通构造====================" << endl;
 89     MyStr str1(1, (char*)"aaa");
 90     cout << "普通构造====================" << endl;
 91     MyStr str2(2, (char*)"bbbb");
 92     cout << "拷贝赋值====================" << endl;
 93     str2 = str1;
 94     cout << "拷贝构造====================" << endl;
 95     MyStr str3 = str2;
 96     cout << "拷贝构造====================" << endl;
 97     MyStr str4(str2);
 98     cout << "移动构造====================" << endl;
 99     MyStr str5(std::move(str2));
100     cout << "移动构造====================" << endl;
101     MyStr str6 = std::move(str5);
102     cout << "普通构造====================" << endl;
103     MyStr str7(3, (char*)"ccccc");
104     cout << "移动赋值====================" << endl;
105     str7 = std::move(str6);
106     return 0;
107 }