C++ 45 之赋值运算符的重载

#include <iostream>
#include <string>
#include <cstring>
using namespace std;class Students05{
public:int m_age;char* m_name;Students05(){}Students05(const char* name,int age){// 申请堆空间保存m_name;this->m_name = new char[strlen(name) + 1];strcpy(this->m_name, name);this->m_age = age;}// 清空堆空间~Students05(){if(this->m_name){delete[] this->m_name;this->m_name = NULL;}}// 重载赋值运算符 = Students05& operator=(const Students05 &p){// 先判断原来的堆区是否有内容if(this->m_name){delete[] this->m_name;this->m_name = NULL;}this->m_name = new char[strlen(p.m_name) + 1];strcpy(this->m_name, p.m_name);this->m_age = p.m_age;return *this;}// 拷贝构造函数重载。使用深拷贝解决浅拷贝的free问题Students05(const Students05 &p){this->m_name = new char[strlen(p.m_name) + 1];strcpy(this->m_name, p.m_name);this->m_age = p.m_age;}
};int main()
{// 编译器默认会给类4个默认函数： 默认构造函数、析构函数、拷贝函数、// 拷贝赋值运算符（operator=）// stu3 = stu2; // 赋值操作 走拷贝赋值运算符（operator=）// Students05 stu3 = stu2; //初始化操作，走复制构造函数 // 此时stu3 刚刚创建// Students05 stu3 = Students05(stu2); //初始化操作，走复制构造函数// Students05 stu1(18);// // Students05 stu2 = stu1; // 相当于Students05 stu2 = Students05(stu1);// Students05 stu2;// stu2 = stu1;// cout << stu1.m_age << endl;Students05 stu1("张三",18);Students05 stu2("四",28);// 执行重载函数时 stu1作为Students05& operator=(const Students05 &p)的参数 里面的this 是stu2stu2 = stu1;   // 这种写法叫赋值   // 默认是浅拷贝，执行delete的时候会报错，学要深拷贝才可以Students05 stu3("王",39);stu3 = stu2 = stu1; // 想链式编程，需要返回当前对象Students05 stu4 = stu3; // 隐式法 调用的默认拷贝构造函数，我们自己用new在堆空间中申请的内存，清空的时候会出现错误，需要重载拷贝构造函数cout << stu1.m_name << stu1.m_age << endl;cout << stu2.m_name << stu2.m_age << endl;cout << stu3.m_name << stu3.m_age << endl;// int a = 10;// int b = 20;// int c;// c = a = b;// cout << "a: " << a << endl;// cout << "b: " << b << endl;// cout << "c: " << c << endl;return 0;
}