C++之双目运算符重载

文章目录

运算符重载
双目运算符重载

运算符重载

cpp 复制代码

#include <iostream>
using namespace std;
class Complex{
private:
    double r;
    double i;
public:
    Complex(double r, double i){
        this->r = r;
        this->i = i;
    }
    void print(void){
        cout << r << " + " << i << "i" << endl;
    }
};
int main(void){
    Complex a(1,2);
    Complex b(3,4);
    a.print();
    b.print();
    int x = 10;
    int y = 20;
    int z = x + y;
    a+b; //想像x+y 实现Complex对象加运算 ＋运算符新的逻辑功能 要实现+运算符的重载
    return 0;
}

双目运算符重载

双目运算符：有左右两个操作数的操作符 L#R
- 算术运算：*、/、%、+、-
- 关系运算：>、>=、<、<=、==、!=
- 逻辑运算：&&、||
- 位运算：&、|、^、<< 、>>
- 赋值与复合赋值：=、+=、-=、*=、/=、%=、&=、|=、^=、<<= 、>>=
- ... ...
注意：
- 表达式结果是右值
- 左右操作数既可以是左值也可以是右值
实现方式：
- 成员函数形式：L.operator#®
- 友元函数形式：operator#(L,R)

cpp 复制代码

#include <iostream>
using namespace std;
class Complex{
private:
    double r;
    double i;
public:
    Complex(double r, double i){
        this->r = r;
        this->i = i;
    }
    void print(void){
        cout << r << " + " << i << "i" << endl;
    }
    const Complex operator+(const Complex& c){
        Complex tmp(r+c.r, i+c.i);
        return tmp;
    }
    friend const Complex operator-(const Complex& l , const Complex& r);
};
const Complex operator-(const Complex& l, const Complex& r){
    Complex tmp(l.r - r.r, l.i - r.i);
    return tmp;
}
int main(void){
    Complex a(1,2);
    Complex b(3,4);
    a.print();
    b.print();
    Complex c = a+b;// a.operator+(b);
    c.print();
    Complex d = c - a; // operator-(c, a);
    d.print();
    return 0;
}

对赋值类双目运算符重载时需要注意的事项：
- 表达式的结果是左值，就是左操作数的自身
- 左操作数必须是左值，右操作数可以是左值也可以是右值

cpp 复制代码

#include <iostream>
using namespace std;
class Complex{
private:
    double r;
    double i;
public:
    Complex(double r, double i){
        this->r = r;
        this->i = i;
    }
    void print(void){
        cout << r << " + " << i << "i" << endl;
    }
    const Complex operator+(const Complex& c){
        Complex tmp(r+c.r, i+c.i);
        return tmp;
    }
    Complex & operator+=(const Complex &c){
        r = r + c.r;
        i = i + c.i;
        return *this;
    }
    friend const Complex operator-(const Complex& l , const Complex& r);
    friend Complex & operator-=(Complex &L, const Complex &R);
};
const Complex operator-(const Complex& l, const Complex& r){
    Complex tmp(l.r - r.r, l.i - r.i);
    return tmp;
}
Complex & operator-=(Complex &L, const Complex &R){
    L.r -= R.r;
    L.i -= R.i;
    return L;
}
int main(void){
    Complex a(1,2);
    Complex b(3,4);
    a.print();
    b.print();
    Complex c = a+b;// a.operator+(b);
    c.print();
    Complex d = c - a; // operator-(c, a);
    d.print();
    a += b; //a.operator+=(b);
    a.print();
    (a -= b).print();
    return 0;
}