C++运算符重载的实现过程和代码
所有运算符重载,都拥有一个统一的名称:operator# (#表示运算符号)
参数:根据运算符本身特点决定,如果是单目运算符,最多拥有一个参数,如果是双目运算符,最多拥有两个参数,返回值由用户自己决定
调用原则:运算符的左侧是函数调用者,右侧是该函数的参数
每个运算符重载,都可以实现两个版本的重载函数,分别是成员函数版和全局函数版
成员函数版比全局函数版本少一个参数,因为类对象本身就是一个参数
全局函数版和成员函数版只能实现一个,否则会造成调用时的混乱情况
全局函数版,需要使用友元函数来完成
#include <iostream>using namespace std;//定义一个复数类 5 + 3i
class Complex
{
private:int real; //实部int vir; //虚部public:Complex() {}Complex(int r, int v):real(r), vir(v) {} //有参构造//定义展示函数void show(){if(vir>=0){cout<<real<<" + "<<vir<<"i"<<endl;}else{cout<<real<<vir<<"i"<<endl;}}//全局函数版实现加运算符重载friend const Complex operator+ (const Complex &L, const Complex &R);//成员函数版实现运算符重载const Complex operator- ( const Complex &R)const{Complex c;c.real = this->real - R.real;c.vir = this->vir - R.vir;return c;}//成员函数版实现关系运算符的重载:实部>实部 && 虚部>虚部bool operator>(const Complex &R)const{return this->real>R.real&&this->vir>R.vir;}//重载中括号运算符int & operator[](int index){if(index == 0){return real; //返回实部}else if(index == 1){return vir; //返回虚部}}//重载+=运算符:实部+=实部 虚部+=虚部Complex & operator+=(const Complex &R){this->real += R.real;this->vir += R.vir;return *this; //返回自身的引用}//重载负号运算符: 实部= -实部, 虚部 = -虚部Complex operator-(){Complex c;c.real = -this->real;c.vir = -this->vir;return c;}//重载前置自增运算符重载函数:实部 = 实部+1 虚部=虚部+1Complex &operator++(){++this->real;++this->vir;return *this;}//重载后置自增运算符重载函数:实部 = 实部+1 虚部=虚部+1Complex operator++(int){Complex c;c.real = this->real++;c.vir = this->vir++;return c;}//将全局函数版实现的输出运算符重载函数设置成友元friend ostream &operator<<(ostream &L, Complex &c);//重载小括号运算符,做一个仿函数void operator()(string s){cout<<s<<endl;}//重载小括号运算符,做一个仿函数void operator()(){cout<<520<<" "<<1314<<endl;}//重写类型转换运算符operator int(){return real; //将该数据类型向int类型转换后,使用的是real的值}};//全局函数版实现加号运算符重载:实部+实部 虚部+虚部
const Complex operator+ (const Complex &L, const Complex &R)
{//定义一个临时空间Complex c;c.real = L.real + R.real;c.vir = L.vir + R.vir;return c;
}//重载输出运算符函数
ostream &operator<<(ostream &L, Complex &c)
{if(c.vir>=0){L<<c.real<<" + "<<c.vir<<"i"<<endl;}else{L<<c.real<<c.vir<<"i"<<endl;}//返回左操作数自身的引用return L;
}int main()
{Complex c1(5,3);c1.show(); //5+3iComplex c2(2,-1);c2.show(); //2-1iComplex c3 = c1-c2; //调用加法运算符重载函数 c1.operator-(c2)c3.show(); //3+4iif(c3 > c2) //调用关系运算符重载函数{cout<<"yes"<<endl;}else{cout<<"no"<<endl;}c3[0] = 5; //将实部进行修改成5,调用中括号运算符重载c3.show(); //5+4ic3 += c2; //调用+=运算符重载函数c3.show(); //7+3iComplex c4 = -c3; //调用-号运算符重载c4.show(); //-7 - 3ic3.show(); //7+3iComplex c5 = ++c3; //调用前置自增运算符重载函数c5.show(); //8+4ic3.show(); //8+4iComplex c6 = c3++; //调用后置自增运算符重载函数c6.show(); //8+4ic3.show(); //9+5icout<<c3; //cout.operator<<(c3)c3("hello world"); //c3.operator()("hello world");c3();int num = (int)c3; //调用类型转换运算符重载函数cout<<"num = "<<num<<endl;return 0;
}