重载赋值运算符

阳光穿透心脏的1/2处 2023-07-04 11:08 9阅读 0赞

*  赋值运算符重载用于对象数据的复制
 *   operator= 必须重载为成员函数
 *  重载函数原型为：

***类型*  & ** ***类名*  :: operator= ( const ** ***类名* & ) ;**

案例：完善Name类，支持=号操作。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW5ndWl5dXl1_size_16_color_FFFFFF_t_70][]

具体看如下代码：

#define  _CRT_SECURE_NO_WARNINGS 
    #include <iostream>
    using namespace std;
    
    class Name
    {
    public:
    	Name(const char* myp)
    	{
    		m_len = strlen(myp);
    		m_p = (char*)malloc(m_len+1);
    		strcpy(m_p,myp);
    	}
    
    	//Name obj2=obj1  这是浅拷贝
    	//解决方案，手工编写深拷贝构造函数
    	Name(const Name& obj1)
    	{
    		cout << "拷贝构造函数" << endl;
    		m_len = obj1.m_len;
    		m_p = (char*)malloc(m_len+1);
    		strcpy(m_p,obj1.m_p);
    	}
    
    	Name& operator=(Name& obj1)
    	{
    		cout << "重载了" << endl;
    		//先释放旧的内存
    		if (this->m_p != NULL)
    		{
    			free(m_p);
    			m_p = NULL;
    			m_len = 0;
    		}
    
    		this->m_len = obj1.m_len;
    		this->m_p = new char[m_len + 1];
    
    		//把obj1赋值
    		strcpy(m_p,obj1.m_p);
    		return *this;
    	}
    
    	~Name()
    	{
    		if (m_p != NULL)
    		{
    			free(m_p);
    			m_p = NULL;
    			m_len = 0;
    		}
    	}
    
    protected:
    private:
    	char* m_p;
    	int m_len;
    };
    
    
    //对象析构的时候，出现coredump
    void objplaymain()
    {
    	Name obj1("abcdefg");
    	Name obj2 = obj1; //调用的是拷贝构造函数，因为这里有个初始化的操作
    	Name obj3("obj3");
    
    	obj3 = obj1; //调用的是等号重载
    
    	
    	obj1 = obj2 = obj3;
    }
    
    
    
    void main()
    {
    	objplaymain();
    	cout << "hello..." << endl;
    	system("pause");
    	return;
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW5ndWl5dXl1_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200210103749966.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RpYW5ndWl5dXl1,size_16,color_FFFFFF,t_70