c++ 学习 之 运算符重载

前言

运算符重载的概念：
对已有的运算符重新进行定义，赋予其另外一种功能，以适应不同的数据类型

加号运算符重载

作用：定义两个自定义的数据类型相加的运算

正常情况下，如果想要实现类中两个int 类型的相加，可以参考下面的代码

#define CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;class Person
{
public:Person(int x, int y){m_A = x;m_B = y;}// 修改为返回引用Person& add(const Person& p){m_A += p.m_A;m_B += p.m_B;return *this;}void print(){cout << "m_A: " << m_A << endl;cout << "m_B: " << m_B << endl;}
private:int m_A;int m_B;
};int main()
{Person A(1, 1);Person B(2, 2);// 使用赋值操作符初始化 cPerson c = A.add(B);c.print();return 0;
}

但是上面的代码的话A 和 c 共同使用同一个地址

看看下面的运算符重载

#define CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;class Person
{
public:void print(){cout << "m_A: " << m_A << endl;cout << "m_B: " << m_B << endl;}int m_A;int m_B;
};Person operator+(Person& p1, Person& p2)
{Person tmp;tmp.m_A = p1.m_A + p2.m_A;tmp.m_B = p1.m_B + p2.m_B;return tmp;}int main()
{Person A;A.m_A = 1;A.m_B = 1;Person B;B.m_A = 2;B.m_B = 2;// Person C = A + B;   这种方式和下面的是等价的Person C = operator+(A, B);C.print();return 0;
}

下面展示成员函数来实现运算符重载

#define CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;class Person
{
public:Person operator+(Person& p1){Person tmp;tmp.m_A = p1.m_A + this->m_A;tmp.m_B = p1.m_B + this->m_B;return tmp;}void print(){cout << "m_A: " << m_A << endl;cout << "m_B: " << m_B << endl;}int m_A;int m_B;
};int main()
{Person A;A.m_A = 1;A.m_B = 1;Person B;B.m_A = 2;B.m_B = 2;Person C = A + B;  // 这种方式和下面的是等价的//Person C = A.operator+(B);C.print();return 0;
}

运算符重载 ,也可以实现 类 与 整形的结合

#define CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;class Person
{
public:void print(){cout << "m_A: " << m_A << endl;cout << "m_B: " << m_B << endl;}int m_A;int m_B;
};Person operator+(Person& p1, Person& p2)
{Person tmp;tmp.m_A = p1.m_A + p2.m_A;tmp.m_B = p1.m_B + p2.m_B;return tmp;}// 下面写一个函数重载
Person operator+(Person& p1, int num)
{Person tmp;tmp.m_A = p1.m_A + num;tmp.m_B = p1.m_B + num;return tmp;
}int main()
{Person A;A.m_A = 1;A.m_B = 1;Person B;B.m_A = 2;B.m_B = 2;// Person C = A + B;   这种方式和下面的是等价的//Person C = operator+(A, B);//C.print();Person D = A + 10;D.print();return 0;
}