C++之运算符重载（三）

这是运算符重载的第三篇文章，上篇地址：

https://blog.csdn.net/zy010101/article/details/105245007

本篇讲述重载等号运算符。直接上代码。

//Human.h
#pragma once


#define _CRT_SECURE_NO_WARNINGS
#include<iostream>

class Human
{
private:
	int age;
	int height;
	char* name;
public:
	Human(int age, int height,const char* name);
	Human(const Human& man);
	~Human();
	Human& operator=(Human& man);		//重载等号运算符
	//重载输出运算符
	friend std::ostream& operator<<(std::ostream& out, const Human& man)
	{
		out << "age:" << man.age << "   height:" << man.height << "   name:" << man.name << std::endl;
		return out;
	}
};

//Human.cpp

#include "Human.h"

Human::Human(int age, int height, const char* name)
{
	this->age = age;
	this->height = height;
	this->name = (char*)malloc(strlen(name) + 1);
	strcpy(this->name, name);
}

Human::Human(const Human& man)
{
	this->age = man.age;
	this->height = man.height;
	this->name = (char*)malloc(strlen(man.name) + 1);
	strcpy(this->name, man.name);
}

Human& Human::operator=(Human& man)
{
	this->age = man.age;
	this->height = man.height;
	if (NULL != this->name)
	{
		free(this->name);
	}
	this->name = (char*)malloc(strlen(man.name) + 1);
	strcpy(this->name, man.name);
	return *this;
}


Human::~Human()
{
	if (NULL != this->name)
	{
		free(this->name);
		this->name = NULL;
	}
}

//main.cpp

#include"Human.h"

int main()
{
	Human man1(3, 50, "Peter");
	std::cout << man1;

	Human man2(33, 182, "LaoWang");
	std::cout << man2;

	man2 = man1;
	std::cout << man2;

	return 0;
}

输出结果如下：

代码中拷贝构造函数的实现和重载等号操作符几乎是一致的，其实这也是因为如果你不重载等号运算符，C++会提供一个默认的等号运算符重载。但是这个运算符重载也是浅拷贝。遇到指针就会出错，这时候就需要我们手动重载等号运算符。这也是为什么不能把它重载为友元函数的原因，因为类内默认提供一个重载等号运算符。你如果重载在类外，那么将会造成调用不明确。

剩下的+=， -+， *=， /=，%=, <<=, >>= , ^=,&=, |=这些运算符可以重载为成员函数，也可以重载为友元函数。

=, [ ],  ( ), ->必须是重载为成员。