[C++ 核心编程]笔记 4.5.1 加号运算符重载

4.5 运算符重载

运算符重载概念: 对已有的运算符重新进行定，赋予其另一种功能，以适应不同的数据类型

4.5.1 加号运算符重载

作用: 实现两个自定义数据类型相加的运算

可以分为三种运算符重载方式:

成员函数重载
全局函数重载
运算符重载也可以发生函数重载

总结
1. 对于内置的数据类型的表述式的的运算符是不可能改变的
2. 不要滥用运算符重载

1. 成员函数重载+号

#include<iostream>
using namespace std;class Person
{
public://1. 成员函数重载+号Person operator+(Person& p){Person temp;temp.m_A = this->m_A+p.m_A;temp.m_B = this->m_B + p.m_B;return temp;}int m_A;int m_B;
};void test01()
{Person p1;p1.m_A = 10;p1.m_B = 10;Person p2;p2.m_A = 10;p2.m_B = 10;//成员函数重载的本质调用Person p3 = p1.operator+(p2);cout << "p3.m_A = " << p3.m_A << endl;cout << "p3.m_B = " << p3.m_B << endl;}int main()
{test01();system("pause");return 0;
}

2. 全局函数重载+号

#include<iostream>
using namespace std;class Person
{
public:int m_A;int m_B;
};Person operator+(Person & p1, Person& p2)
{Person temp;temp.m_A = p1.m_A + p2.m_A;temp.m_B = p1.m_B + p2.m_B;return temp;
}void test01()
{Person p1;p1.m_A = 10;p1.m_B = 10;Person p2;p2.m_A = 10;p2.m_B = 10;//全局函数重载的本质调用//Person p3 = operator+(p1, p2);Person p3 = p1 + p2;cout << "p3.m_A = " << p3.m_A << endl;cout << "p3.m_B = " << p3.m_B << endl;
}
int main()
{test01();system("pause");return 0;
}

3. 运算符重载也可以发生函数重载

#include<iostream>
using namespace std;class Person
{
public:int m_A;int m_B;
};Person operator+(Person &p1,int num)
{Person temp;temp.m_A = p1.m_A + num;temp.m_B = p1.m_B + num;return temp;
}
void test01()
{Person p1;p1.m_A = 10;p1.m_B = 10;Person p2;p2.m_A = 10;p2.m_B = 10;//运算符重载 也可以发生函数重载Person p4 = p1 + 100;//Person + intcout << "p4.m_A = " << p4.m_A << endl;cout << "p4.m_B = " << p4.m_B << endl;
}
int main()
{test01();system("pause");return 0;
}

全部代码:

#include<iostream>
using namespace std;//加号运算符重载
class Person
{
public://1. 成员函数重载+号//Person operator+(Person& p)//{//	Person temp;//	temp.m_A = this->m_A+p.m_A;//	temp.m_B = this->m_B + p.m_B;//	return temp;//}int m_A;int m_B;};//2. 全局函数重载+号
Person operator+(Person & p1, Person& p2)
{Person temp;temp.m_A = p1.m_A + p2.m_A;temp.m_B = p1.m_B + p2.m_B;return temp;
}//函数重载的版本
Person operator+(Person &p1,int num)
{Person temp;temp.m_A = p1.m_A + num;temp.m_B = p1.m_B + num;return temp;
}void test01()
{Person p1;p1.m_A = 10;p1.m_B = 10;Person p2;p2.m_A = 10;p2.m_B = 10;//成员函数重载的本质调用//Person p3 = p1.operator+(p2);//全局函数重载的本质调用//Person p3 = operator+(p1, p2);Person p3 = p1 + p2;//运算符重载 也可以发生函数重载Person p4 = p1 + 100;//Person + intcout << "p3.m_A = " << p3.m_A << endl;cout << "p3.m_B = " << p3.m_B << endl;cout << "p4.m_A = " << p4.m_A << endl;cout << "p4.m_B = " << p4.m_B << endl;
}int main()
{test01();system("pause");return 0;
}