普通运算符重载

• C++准许以运算符命名函数

  string love = "i";
  
  love += " love";//+(love, " love");
  love += " you";//+(love, " you");
  
  cout<< "i love you";// <<(cout, "i love you");
  

• 运算符分类

  数学运算符

  +  -  *  /  ++  --
  

  关系运算符

  ==  >=  <= !=
  

  特殊运算符

  [ ]
   =  赋值运算符
  （）仿函数
  << 输出运算符
  

数学运算符关系运算符例子

#include <stdio.h>
#include <unistd.h>


class myTimer{
public:
    myTimer(){
        hour = 0;
        min = 0;
        sec = 0;
    }
    ~myTimer(){

    }
    void addtimer(int sec = 1){
        this->sec = this->sec + sec;
    }
    void showtime(){
        printf("%02d:%02d:%02d\n",hour / 3600,min / 60,sec % 60);
    }
    //重载5
    bool operator == (myTimer &x){
        return (sec == x.sec && min == x.min && hour == x.hour) ? true : false;
    }

    //重载4 ++t
    myTimer operator++(){
        sec++;
        return *this;
    }

    /********所以一般写代码循环尽量用++i,因为i++会有拷贝过程******/
    //重载3  t++
    myTimer operator ++ (int){
        myTimer tmp = *this;//先记录自己
        sec++;//自己++
        return tmp;//返回之前的
    }
    //重载2
    myTimer operator + (int t){
        myTimer tmp;
        tmp.sec = sec + t;
        return tmp;
    }
    //重载1
    myTimer operator + (myTimer &x){
        myTimer tmp;
        tmp.sec = sec + x.sec;
        tmp.min = x.min;
        tmp.hour = x.hour;
        return tmp;
    }
private:
    int hour;
    int min;
    int sec;
};


int main(int argc, char const *argv[])
{
    myTimer t1;
    t1.addtimer(3);
    myTimer t2;
    t2.addtimer(6);
    myTimer t3;
    
    t3 = t2++;//重载3   先赋值再加
    printf("重载3 ");
    t3.showtime();

    t3 = ++t2;//重载4   先加再赋值
    printf("重载4 ");
    t3.showtime();

    printf("重载5 ");
    if(t2 == t3)//重载5
        printf("==\n");
    else
        printf("!=\n");
    
    printf("重载1 ");
    t3 = t1 + t2;//重载1
    t3.showtime();

    printf("重载2 ");
    t3 = t3 + 2;//重载2
    t3.showtime();
    
    printf("重载5 ");
    if(t2 == t3)//重载5
        printf("==\n");
    else
        printf("!=\n");
    
    return 0;
}

结果