当前位置： 首页 > news >正文

类和对象（高级）

news 2025/11/26 19:11:12

类和对象（高级）

一、运算符重载

运算符重载是对已有的运算符 指定新功能。不能创建新运算。
运算符重载关键字operator
思路：
1、弄懂运算符的运算对象的个数。（个数决定了 重载函数的参数个数）
2、识别运算符左边的运算对象 是类的对象还是其他.
类的对象：成员函数实现（推荐，少一个参数），全局函数实现（不推荐）
其他：只能是全局函数实现

1、重载<<运算符（全局函数实现）

#include <iostream>
#include<string>
using namespace std;
class Person{friend ostream& operator <<(ostream &out,Person &ob );
private:int  num;string name;float score;
public:Person(){}Person(int num,string name,float score):num(num),name(name),score(score){}
};
//返回cout的引用类型（可以链式输出）
ostream& operator <<(ostream &out,Person &ob ){out<<ob.num<<" "<<ob.name<<" "<<ob.score;return out;
}
int main(int argc, char *argv[])
{Person lucy(100,"lucy",19.2f);Person bob(102,"bob",19.3f);cout<<lucy<<endl;//链式 输出cout<<lucy<<bob<<endl;return 0;
}

2、重载输入>>运算符

#include <iostream>
#include<string>
using namespace std;
class Person{friend ostream& operator<<(ostream &out,Person &ob );friend istream& operator>>(istream &in,Person &ob);
private:int  num;string name;float score;
public:Person(){}Person(int num,string name,float score):num(num),name(name),score(score){}};
//返回cout的引用类型（可以链式输出）
ostream& operator<<(ostream &out,Person &ob ){out<<ob.num<<" "<<ob.name<<" "<<ob.score;return out;
}
istream &operator>>(istream &in,Person &ob){
in>>ob.num>>ob.name>>ob.score;
return in;
}
int main(int argc, char *argv[])
{Person lucy;cin>>lucy;cout<<lucy<<endl;return 0;
}

如果使用全局函数 重载运算符 必须将全局函数设置成友元。

3、可以重载的运算符

在这里插入图片描述

4、重载加法运算符+（全局函数实现）

#include <iostream>
#include<string>
using namespace std;
class Person{friend ostream& operator<<(ostream &out,Person ob );friend istream& operator>>(istream &in,Person &ob);friend Person operator +(Person ob1,Person ob2);
private:int  num;string name;float score;
public:Person(){}Person(int num,string name,float score):num(num),name(name),score(score){}};
//返回cout的引用类型（可以链式输出）
ostream& operator<<(ostream &out,Person ob ){out<<ob.num<<" "<<ob.name<<" "<<ob.score;return out;
}
istream &operator>>(istream &in,Person &ob){
in>>ob.num>>ob.name>>ob.score;
return in;
}
//返回值不能为引用，因为temp是局部变量
Person operator +(Person ob1,Person ob2){Person temp;temp.num=ob1.num+ob2.num;temp.name=ob1.name+ob2.name;temp.score=ob1.score+ob2.score;return temp;}
int main(int argc, char *argv[])
{Person lucy(100,"lucy", 88.8f);Person bob(101,"bob", 99.9f);Person tom(102,"tom", 77.7f);cout<<lucy+bob+tom<<endl;return 0;
}

5、重载加法运算符+（成员函数实现 推荐）

#include <iostream>
#include<string>
using namespace std;
class Person{friend ostream& operator<<(ostream &out,Person ob );friend istream& operator>>(istream &in,Person &ob);
private:int  num;string name;float score;
public:Person(){}Person(int num,string name,float score):num(num),name(name),score(score){}
//成员函数实现重载Person operator +(Person ob2){Person temp;temp.num=this->num+ob2.num;temp.name=this->name+ob2.name;temp.score=this->score+ob2.score;return temp;}};
//返回cout的引用类型（可以链式输出）
ostream& operator<<(ostream &out,Person ob ){out<<ob.num<<" "<<ob.name<<" "<<ob.score;return out;
}
istream &operator>>(istream &in,Person &ob){
in>>ob.num>>ob.name>>ob.score;
return in;
}int main(int argc, char *argv[])
{Person lucy(100,"lucy", 88.8f);Person bob(101,"bob", 99.9f);Person tom(102,"tom", 77.7f);cout<<lucy+bob+tom<<endl;return 0;
}

6、重载==运算符（成员函数实现 推荐）

#include <iostream>
#include<string>
using namespace std;
class Person{friend ostream& operator<<(ostream &out,Person ob );friend istream& operator>>(istream &in,Person &ob);
private:int  num;string name;float score;
public:Person(){}Person(int num,string name,float score):num(num),name(name),score(score){}Person operator +(Person ob2){Person temp;temp.num=this->num+ob2.num;temp.name=this->name+ob2.name;temp.score=this->score+ob2.score;return temp;}//成员函数重载==运算符bool operator ==(Person &ob){if(num==ob.num&&name==ob.name&&score==ob.score){return true;}else{return false;}}};
//返回cout的引用类型（可以链式输出）
ostream& operator<<(ostream &out,Person ob ){out<<ob.num<<" "<<ob.name<<" "<<ob.score;return out;
}
istream &operator>>(istream &in,Person &ob){
in>>ob.num>>ob.name>>ob.score;
return in;
}int main(int argc, char *argv[])
{Person lucy(100,"lucy", 88.8f);
//     Person bob(101,"bob", 99.9f);Person bob(100,"lucy", 88.8f);
if(lucy==bob){
cout<<"相等"<<endl;
}
else{cout<<"不相等"<<endl;
}return 0;
}

7、重载++运算符

++a(前置++)，它就调用operator++(a),
a++（后置++），它就会去调用operator++(a,int)

案例1：重载后置++

类名称 operator++(int)
{old=//先保存旧的值
//自增++return old;//返回旧值}

#include <iostream>
#include<string>
using namespace std;
class Person{friend ostream& operator<<(ostream &out,Person ob );friend istream& operator>>(istream &in,Person &ob);
private:int  num;string name;float score;
public:Person(){}Person(int num,string name,float score):num(num),name(name),score(score){}Person operator +(Person ob2){Person temp;temp.num=this->num+ob2.num;temp.name=this->name+ob2.name;temp.score=this->score+ob2.score;return temp;}bool operator ==(Person &ob){if(num==ob.num&&name==ob.name&&score==ob.score){return true;}else{return false;}}//后置++Person  operator ++(int a){Person old;old.num=num;old.name=name;old.score=score;num+=1;name+=name;score+=score;return old;}};
//返回cout的引用类型（可以链式输出）
ostream& operator<<(ostream &out,Person ob ){out<<ob.num<<" "<<ob.name<<" "<<ob.score;return out;
}
istream &operator>>(istream &in,Person &ob){
in>>ob.num>>ob.name>>ob.score;
return in;
}int main(int argc, char *argv[])
{Person lucy(100,"lucy", 88.8f);Person bob;//先使用后++bob = lucy++;cout<<bob<<endl;cout<<lucy<<endl;return 0;
}

案例2：重载前置++

#include <iostream>
#include<string>
using namespace std;
class Person{friend ostream& operator<<(ostream &out,Person ob );friend istream& operator>>(istream &in,Person &ob);
private:int  num;string name;float score;
public:Person(){}Person(int num,string name,float score):num(num),name(name),score(score){}Person operator +(Person ob2){Person temp;temp.num=this->num+ob2.num;temp.name=this->name+ob2.name;temp.score=this->score+ob2.score;return temp;}bool operator ==(Person &ob){if(num==ob.num&&name==ob.name&&score==ob.score){return true;}else{return false;}}Person  operator ++(int a){Person old;old.num=num;old.name=name;old.score=score;num+=1;name+=name;score+=score;return old;}
//前置++Person operator ++(){num+=1;name+=name;score+=score;return *this;//返回自身的值}};
//返回cout的引用类型（可以链式输出）
ostream& operator<<(ostream &out,Person ob ){out<<ob.num<<" "<<ob.name<<" "<<ob.score;return out;
}
istream &operator>>(istream &in,Person &ob){
in>>ob.num>>ob.name>>ob.score;
return in;
}int main(int argc, char *argv[])
{Person lucy(100,"lucy", 88.8f);Person bob;//先++ 后使用bob = ++lucy;cout<<bob<<endl;cout<<lucy<<endl;// bob等于lucyreturn 0;
}

在这里插入图片描述

8、重载()运算符

重载（）运算符 一般用于 为算法 提供策略。

#include <iostream>
using namespace std;
class Print{
public:void operator()(char *str){cout<<str<<endl;}};int main()
{Print ob;//对象和()结合 触发operator()成员函数 调用ob("Hello World");//匿名成员Print()("hello world");return 0;
}

二、自定义string类

重载构造函数

#include <iostream>
#include<string.h>
using namespace std;class MyString{private:int  size;char *str;
public:MyString();//无参构造MyString(char *str);//带参构造MyString(const MyString &ob);//深拷贝~MyString();//析构函数
};MyString::MyString(){str=NULL;size=0;
}
MyString::MyString(char *str){size=strlen(str);this->str=new char[size+1];memset(this->str,0,size+1);strcpy(this->str,str);
}MyString::MyString(const MyString &ob){size=ob.size;str=new char[size+1];memset(str,0,size+1);strcpy(str,ob.str);}MyString::~MyString(){if(str!=NULL){delete[]str;str=NULL;}
}int main(int argc, char *argv[])
{return 0;
}

重载输入输出（全局函数实现）

设为友元函数

friend ostream& operator<<(ostream &out,MyString ob);
friend istream& operator >>(istream &in,MyString &ob);

全局函数实现

ostream& operator<<(ostream &out,MyString ob){out<<ob.str;return out;
}
istream& operator >>(istream &in,MyString &ob){char  buff[1024]="";cin>>buff;if(ob.str!=NULL){delete[]ob.str;ob.str=NULL;}ob.size=strlen(buff);ob.str=new char[ob.size+1];memset(ob.str,0,ob.size+1);strcpy(ob.str,buff);return in;
}

重载括号运算符

在这里插入图片描述
类中声明，类外定义

 char& MyString::operator [](int pos){if(pos<0||pos>=size){cout<<"元素位置不合法"<<endl;exit(-1);}return str[pos];}

重载+运算符

在这里插入图片描述

类外实现

 MyString MyString::operator +(MyString ob){MyString temp;temp.size=size+ob.size;temp.str=new char[temp.size+1];memset( temp.str,0,temp.size+1);strcpy(temp.str,str);strcat(temp.str,ob.str);return temp;}MyString MyString::operator +(char *str){MyString temp;temp.size=this->size+strlen(str);temp.str=new char[temp.size+1];memset(temp.str,0,temp.size+1);strcpy(temp.str,this->str);strcat(temp.str,str);return temp;}

重载=赋值运算符（深拷贝）

在这里插入图片描述

 MyString &MyString::operator =(MyString ob){if(this->str!=NULL){delete[]this->str;this->str=NULL;}this->size=ob.size;this->str=new char[this->size+1];memset(this->str,0,this->size+1);strcpy(this->str,ob.str);return *this;}MyString &MyString::operator =(char *str){if(this->str!=NULL){delete[]this->str;this->str=NULL;}this->size=strlen(str);this->str=new char[this->size+1];memset(this->str,0,this->size+1);strcpy(this->str,str);return *this;}

重载>运算符

在这里插入图片描述

 bool MyString::operator>(MyString ob){if(str==NULL||ob.str==NULL){exit(-1);}if(strcmp(this->str,ob.str)>0){return  true;}else{return false;}}bool MyString::operator >(char *str){if(str==NULL||this->str==NULL){exit(-1);}if(strcmp(this->str,str)>0){return  true;}else{return false;}}

三、智能指针

智能指针：解决 堆区空间的对象释放问题

前言：

#include <iostream>
using namespace std;
class Data{
public:Data(){cout<<"无参构造"<<endl;}~Data(){cout<<"析构函数"<<endl;}void func(){cout<<"func函数"<<endl;}
};int main()
{Data *ob=new Data();//通过new申请堆区空间return 0;
}

结果：只打印了无参构造，并没有调用析构函数

无参构造

设置智能指针

#include <iostream>
using namespace std;
class Data{
public:Data(){cout<<"无参构造"<<endl;}~Data(){cout<<"析构函数"<<endl;}void func(){cout<<"func函数"<<endl;}
};class SmartPointer{private:Data *p;
public:SmartPointer(){}SmartPointer(Data *p){this->p=p;}~SmartPointer(){delete p;}};int main()
{SmartPointer ob(new Data);return 0;
}
无参构造
析构函数

结果是调用了析构函数，运用的原理就是生命周期

我们在类中

    //重载*运算符Data& operator*(){return *p;}//重载->运算符Data* operator->(){return p;}

#include <iostream>
using namespace std;
class Data{
public:Data(){cout<<"无参构造"<<endl;}~Data(){cout<<"析构函数"<<endl;}void func(){cout<<"func函数"<<endl;}
};class SmartPointer{private:Data *p;
public:SmartPointer(){}SmartPointer(Data *p){this->p=p;}~SmartPointer(){delete p;}//重载*运算符Data& operator*(){return *p;}//重载->运算符Data* operator->(){return p;}};int main()
{SmartPointer ob(new Data);//访问通过SmartPointer访问pob.operator *().func();ob.operator->()->func();(*ob).func();ob->func();return 0;
}

http://www.mrgr.cn/news/5449.html

相关文章：

  • 一文了解检索增强生成（RAG）
  • Spark2.x 入门：DStream 输出操作
  • 4170条中医综合真题中医真题ACCESS\EXCEL数据库
  • Java List 结合删除元素的方法
  • 神经网络算法 - 一文搞懂GAN（生成对抗网络）
  • 2408gui,wtl给对话框加快捷键
  • Spring + Boot + Cloud + JDK8 + Elasticsearch 单节点 模式下实现全文检索高亮-分页显示 快速入门案例
  • 查看U盘的具体信息，分区表格式、实际容量和分区状态
  • 100个智能体实战技巧 | 如何让工作流也能处理图片
  • 中兴 5G CPE 3 Pro产品参数
  • Spring Cloud LoadBalancer 源码解析
  • 【UE5.1】NPC人工智能——05 给NPC添加视觉感知
  • 数采网关面临的安全挑战
  • 【3.1】贪心算法-解分发饼干
  • Windows Server查看W3SVC IIS服务器中对应的网站日志
  • centos 7.9 迁移到 openEuler22.03-LTS-SP3
  • 微信小程序电脑端和开发工具端能访问，但是手机端访问不了
  • TypeScript中的接口(Interface):对象类型的强大工具
  • 用py获取显卡的占用率
  • 全套安全帽佩戴检测算法源码与实战应用分享