C++学习:运算符重载

简介:

类是用户自定义的数据类型,使用重载运算符好可以实现一下的逻辑

1:对象3 = 对象1+对象2+...如描述复数的类,描述字符串的类等等
2:提高程序的可读性.

重载赋值运算符

如果一个类没有赋值运算符,系统会默认提供一个

如果一个类已经提供了一个拷贝构造函数(非默认),那么也需要提供一个重载的赋值运算符

如:

Student & Student ::operate=(const Student &stu){
    if(this == &stu){
        return *this;
    }        
    delete[] m_data;
    int length = strlen(other.m_data);
    m_data = new char[length+1];
    strcpy(m_data,other.m_data);
    return *this;
}

提示:

本文博主:章飞_906285288

博客地址:http://blog.csdn.net/qq_29924041

运算符重载

运算符重载特点及注意事项:

C++语言规定:

1:重载的运算符要保持原来运算符的意义
    2:只能对已有的运算符,而不能对新的运算符
    3:重载运算符不会改变原先的优先级和结合性

运算符重载的形式:

1:成员函数形式
2:友元函数的形式

运算符重载的限制:

通过一张图的形式展示下:

C++学习:运算符重载

从上面的图中可以看到,以上的一些运算符号都是可以进行重载的.

而不能重载的运算符有以下一些:

C++学习:运算符重载

以上两张图都是取自百度图片

简单归纳一下一些常用的可重载运算符:

+           -            *
        =           >           <
        <=         >=         <<
        >>         []           ()
        ->          new       new[]
        delete    delete[]

实例代码部分:

友元函数重载

/*
 * ===========================================================================
 *
 *       Filename:  studentTest.cpp
 *    Description:  
 *        Version:  1.0
 *        Created:  2017年06月13日 23时01分07秒
 *       Revision:  none
 *       Compiler:  gcc
 *         Author:   (), 
 *        Company:  
 *
 * ===========================================================================
 */

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
using namespace::std;

class Student{
  public:
     Student(const char* name = "NULL",int stu_math_score = ):math_score(stu_math_score){
        m_name = (char *)malloc(strlen(name)*sizeof(char));
        strncpy(m_name,name,strlen(name)*sizeof(char));
        cout<<"Student constructor"<<endl;
     }

     ~Student(){
       free(m_name);
       cout<<"Student desctructor"<<endl;
     }

    Student(const Student &stu){
      //深拷贝
        m_name = (char *)malloc(strlen(stu.m_name)*sizeof(char));
        strncpy(m_name,stu.m_name,strlen(stu.m_name)*sizeof(char));
        math_score = stu.math_score;
    }

    void print_stu_info(){
      cout<<"================="<<endl;
      cout<<"student name:"<<m_name<<endl;
      cout<<"student math_score:"<<math_score<<endl;
      cout<<"================="<<endl;
    }
     friend int operator+(Student &,Student&);//输出两个学生的成绩和
     friend int operator-(Student &,Student&);//输出两个学生的成绩差
     friend bool operator>(Student &,Student &);//判断第一个学生的数学成绩是否大于第二个学生的数学成绩
     friend Student operator<(Student &,Student &);//将数学成绩少的学生成绩输出
  private:
     char *m_name;
     int math_score;

};

int operator+(Student &stu1,Student &stu2){
  int ret = stu1.math_score + stu2.math_score;
  return ret;
}

int operator-(Student &stu1,Student &stu2){
  int ret = stu1.math_score - stu2.math_score;
  return ret;
}

bool operator>(Student &stu1,Student &stu2){
  return stu1.math_score > stu2.math_score;
}

Student operator<(Student &stu1,Student &stu2){
  Student stu = stu1.math_score < stu2.math_score ? stu1 :stu2;
  return stu;
}


int main(int agrc,char *argv[]){
  Student stu_zhangsan("zhangsan",);
  stu_zhangsan.print_stu_info();
  Student stu_lisi("lisi",);
  stu_lisi.print_stu_info();

  int result = stu_zhangsan +stu_lisi;
  cout<<"add:"<<result <<endl;

  result = stu_zhangsan - stu_lisi;
  cout<<"sub:"<<result <<endl;

  Student stu = stu_zhangsan < stu_lisi;
  stu.print_stu_info();

  bool is_greater_than = stu_zhangsan > stu_lisi;

  cout<<is_greater_than<<endl;

  return ;
}

输出的结果为:

Student constructor

=================

student name:zhangsan

student math_score:85

=================

Student constructor

=================

student name:lisi

student math_score:83

=================

add:168

sub:2

=================

student name:lisi

student math_score:83

=================

Student desctructor

从上面的测试代码中可以很直观的看到,stu_zhansan 和stu_lisi两个对象,他们之间可以去直接进行运算符之间的加减.很直观.也是使用友元函数来进行的操作的(友元函数是不依赖于类的,注意友元函数在定义的时候的写法)

成员运算符重载

二元成员运算符重载的时候,参数只要传一个就行了,另外一个由this指针进行传入

/*
 * ===========================================================================
 *
 *       Filename:  studentTest.cpp
 *    Description:  
 *        Version:  1.0
 *        Created:  2017年06月13日 23时01分07秒
 *       Revision:  none
 *       Compiler:  gcc
 *         Author:   (), 
 *        Company:  
 *
 * ===========================================================================
 */

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
using namespace::std;

class Student{
  public:
     int english_score;
     int math_score;
     Student(const char* name = "NULL",int stu_math_score = ,int english_score = ):math_score(stu_math_score),english_score(english_score){
        m_name = (char *)malloc(strlen(name)*sizeof(char));
        strncpy(m_name,name,strlen(name)*sizeof(char));
        cout<<"Student constructor"<<endl;
     }

     ~Student(){
       free(m_name);
       cout<<"Student desctructor"<<endl;
     }

    Student(const Student &stu){
      //深拷贝
        m_name = (char *)malloc(strlen(stu.m_name)*sizeof(char));
        strncpy(m_name,stu.m_name,strlen(stu.m_name)*sizeof(char));
        math_score = stu.math_score;
        english_score = stu.english_score;
    }

    void print_stu_info(){
      cout<<"================="<<endl;
      cout<<"student name:"<<m_name<<endl;
      cout<<"student math_score:"<<math_score<<endl;
      cout<<"student english_score:"<<english_score<<endl;
      cout<<"================="<<endl;
    }

    //二元运算符重载的时候只需要传一个参数,另一个参数由this指针进行传入
    int operator+(int english);//输出学生的成绩和
    int operator-(int english);//输出学生的成绩差
    bool operator>(int english);//判断学生的数学成绩是否大于学生的英语成绩
    friend Student operator<(Student &,Student &);//将数学成绩少的学生成绩输出

    int operator()(int english);//对象可以使用(),来进行运算符重载,利用重载()来构建可变参数列表
    int operator()(int a,int b,int c,int d);
  private:
     char *m_name;
};

int Student::operator+(int english){
  int ret = this->math_score + english;
  return ret;
}

int Student::operator-(int english){
  int ret = this->math_score - english;
  return ret;
}

bool Student::operator>(int english){
  return this->math_score > english;
}

Student operator<(Student &stu1,Student &stu2){
  Student stu = stu1.math_score < stu2.math_score ? stu1 :stu2;
  return stu;
}

int Student::operator()(int b) {
  return this->math_score+b;
}

int Student::operator()(int a,int b,int c,int d){
  return a+b+c+d;
}

int main(int agrc,char *argv[]){
  Student stu_zhangsan("zhangsan",,);
  stu_zhangsan.print_stu_info();
  int ret = stu_zhangsan.math_score - stu_zhangsan.english_score;
  cout<<"sub:"<<ret<<endl;
  ret =  stu_zhangsan.math_score +stu_zhangsan.english_score;
  cout<<"add:"<<ret<<endl;

  bool  result= stu_zhangsan.math_score > stu_zhangsan.english_score;
  cout<<"bool:"<<result<<endl;

  //直接通过()进行运算
  ret  = stu_zhangsan();
  cout<<"ret:"<<ret<<endl;

  ret = stu_zhangsan(,,,);
  cout<<"ret2:"<<ret<<endl;
  return ;
}

输出的结果为:

Student constructor
 =================
student name:zhangsan
student math_score:85
student english_score:90
=================
sub:-5
add:175
bool:0
ret:175
ret2:100
Student desctructor

C++学习:运算符重载

运算符重载

友元函数重载

成员运算符重载

继续阅读

241 Different Ways to Add Parentheses（C代码版）

2021-08-13c++——类之操作符重载

swmm与lisflood-fp源码如何一起编译 CMake命令

Windows下VS开发环境环境安装工程项目设置关于Debug和Release的提示

一文看懂字符串的加减乘除

C++ 第十五周报告1--《冒泡法排序》

C语言：初学者必定看懂的注释！！！猴子吃桃问题。猴子第一天摘下若干个桃子，每天都吃了前一天剩下的一半零一个，到第10天早上想再吃的时候，就剩下一个桃子. 求第一天共摘多少个桃子。

[转]九大排序算法——C语言实现及详解

C++实现简单顺序表

while 循环、do- while 循环和 for 循环之间的那点事C语言自学之三种循环比较

结构体：typedef与struct的区别

C经典书籍笔记——C陷阱与缺陷②(语法陷阱之优先级)一、错误案列二、优先级规律

线性表之顺序表的实现

C++判断素数、求最大公约数代码判断一个数是否为素数求两个数的最大公约数

SequoiaDB巨杉数据库C++驱动概述

hdu7108哈希