C++等號操作符重載

在新學操作符重載時最令人頭疼的可能就是一些堆溢出的問題了，不過呢，只要一步步的寫好new 與 delete。絕對不會有類似的問題。

當時我們編譯可以通過，但是運行會出錯，因為對象s1與s2進行賦值時，采用淺拷貝，導致對象析構時會對同一塊內存空間析構兩次。也就是說等號操作符“=”，默認是進行淺拷貝，我們需要對等號操作符進行重載，使其能夠進行深拷貝。

同時要重載等號操作符支持鏈式編程，類如 s3 = s4 = s5;  //操作符使對象連載疊加，與上一篇的return *this 與 return this已經介紹過如何返回對象本身。而不是克隆。

這里寫了 重載等號操作符實現深拷貝 與 操作符使對象連載疊加 的代碼。

           #define _CRT_SECURE_NO_WARNINGS 
          
#include <iostream> 
          
#include<string.h> 
          
#include<windows.h> 
          
using namespace std; 
         

           class student 
          
{ 
          
public: 
          
 student() 
          
 { 
          
  //默認構造函數 
          
  cout << "This is studnt();" << endl; 
          
  this->id = 0; 
          
  this->name = NULL; 
          
 } 
          
 student(int id, const char *name) 
          
 { 
          
  this->id = id; 
          
  //深拷貝構造 
          
  int len = strlen(name); 
          
  this->name = new char[len + 1]; 
          
  strcpy(this->name, name); 
          
 } 
          
 student(const student &another) 
          
 { 
          
  //拷貝構造 
          
  this->id = another.id; 
          
  int len = strlen(another.name); 
          
  this->name = new char[len + 1]; 
          
  strcpy(this->name, another.name); 
          
 } 
          
 student & operator=(const student &another) 
          
 { 
          
  // 1.防止自身賦值 
          
  if (this == &another) 
          
  { 
          
   return *this; 
          
  } 
          
  // 2. 給自己額外開辟的內存空間釋放掉 
          
  if (this->name != NULL) 
          
  { 
          
   delete[] this->name; 
          
   this->name = NULL; 
          
   this->id = 0; 
          
  } 
          
  //3. 執行深拷貝 
          
  this->id = another.id; 
          
  int len = strlen(another.name); 
          
  this->name = new char[len + 1]; 
          
  strcpy(this->name, another.name); 
         

             return *this; 
          
 } 
          
 void printf_id_name() 
          
 { 
          
  cout << "id= " << id << " name= " << name << endl; 
          
 } 
          
 ~student() 
          
 { 
          
  if (this->name != NULL) 
          
  { 
          
   delete[] this->name; 
          
   this->name = NULL; 
          
   this->id = 0; 
          
  } 
          
 } 
          
private: 
          
 int id; 
          
 char *name; 
          
}; 
         

 
          
int main(void) 
          
{ 
         

            student s1(1, "C++"); 
          
 student s2; 
          
 student s3(3, "ZJD666"); 
          
  
          
 s2=s3; //深拷貝 等號操作符重載 
          
 s1.printf_id_name(); 
          
 s2.printf_id_name(); 
          
 s3.printf_id_name(); 
          
 cout <<" --------------------------" << endl; 
         

            student s4(4, "Hello World!"); 
          
 student s5(5, "Hello C++!"); 
         

            s3 = s4 = s5;  //操作符連載 
          
 s3.printf_id_name(); 
         

            system("pause"); 
          
 return 0; 
          
} 
         

供學習等號操作符重載參考！！