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运算符重载

#include<iostream>usingnamespacestd;classComplex{private:doubler;doublei;public:Complex(doubler,doublei){this->r=r;this->i=i;}voidprint(void){cout<<r<<" + "<<i<<"i"<<endl;}};intmain(void){Complexa(1,2);Complexb(3,4);a.print();b.print();intx=10;inty=20;intz=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return0;}

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)

#include<iostream>usingnamespacestd;classComplex{private:doubler;doublei;public:Complex(doubler,doublei){this->r=r;this->i=i;}voidprint(void){cout<<r<<" + "<<i<<"i"<<endl;}constComplexoperator+(constComplex&c){Complextmp(r+c.r,i+c.i);returntmp;}friendconstComplexoperator-(constComplex&l,constComplex&r);};constComplexoperator-(constComplex&l,constComplex&r){Complextmp(l.r-r.r,l.i-r.i);returntmp;}intmain(void){Complexa(1,2);Complexb(3,4);a.print();b.print();Complex c=a+b;// a.operator+(b);c.print();Complex d=c-a;// operator-(c, a);d.print();return0;}

• 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

#include<iostream>usingnamespacestd;classComplex{private:doubler;doublei;public:Complex(doubler,doublei){this->r=r;this->i=i;}voidprint(void){cout<<r<<" + "<<i<<"i"<<endl;}constComplexoperator+(constComplex&c){Complextmp(r+c.r,i+c.i);returntmp;}Complex&operator+=(constComplex&c){r=r+c.r;i=i+c.i;return*this;}friendconstComplexoperator-(constComplex&l,constComplex&r);friendComplex&operator-=(Complex&L,constComplex&R);};constComplexoperator-(constComplex&l,constComplex&r){Complextmp(l.r-r.r,l.i-r.i);returntmp;}Complex&operator-=(Complex&L,constComplex&R){L.r-=R.r;L.i-=R.i;returnL;}intmain(void){Complexa(1,2);Complexb(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();return0;}