C++運算符重載的詳細講解

更新時間：2021年04月07日 10:00:50 作者：Thrush''''s note

這篇文章主要給大家介紹了關(guān)于C++運算符重載的相關(guān)資料，文中通過示例代碼介紹的非常詳細，對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值，需要的朋友們下面隨著小編來一起學(xué)習(xí)學(xué)習(xí)吧

加號運算符重載

對于內(nèi)置數(shù)據(jù)類型，編譯器知道如何運算

但是對于自己封裝的類，編譯器無法進行運算

這時可以通過自己定義運算符重載進行運算

operator+

通過成員函數(shù)重載+號

#include<iostream>
using namespace std;
class Person
{
public:
 int m_a;
 int m_b;
 //通過成員函數(shù)實現(xiàn)重載
 Person operator+ (Person &p)
 {
 //創(chuàng)建一個臨時變量
 Person temp;
 temp.m_a = this->m_a + p.m_a;
 temp.m_b = this->m_b + p.m_b;
 return temp;
 }
};
void test01()
{
 Person p1;
 p1.m_a = 66;
 p1.m_b = 44;
 Person p2;
 p2.m_a = 6;
 p2.m_b = 4;
 Person p3;
 //通過函數(shù)原型調(diào)用
 p3 = p1.operator+(p2);
 //簡便調(diào)用
 //p3 = p1 + p2;
 cout << "p3.m_a:" << p3.m_a << endl;
 cout << "p3.m_b:" << p3.m_b << endl;
}

int main()
{
 test01();
 system("pause");
 return 0;
}

注意兩種調(diào)用方式

通過函數(shù)原型調(diào)用

p3 = p1.operator+(p2);

簡便調(diào)用

p3 = p1 + p2;

通過全局函數(shù)重載+號

#include<iostream>
using namespace std;
class Person
{
public:
 int m_a;
 int m_b;
};
//通過全局函數(shù)實現(xiàn)重載
Person operator+ (Person& p1, Person& p2)
{
 //創(chuàng)建一個臨時變量
 Person temp;
 temp.m_a = p1.m_a + p2.m_a;
 temp.m_b = p1.m_b + p2.m_b;
 return temp;
}
void test01()
{
 Person p1;
 p1.m_a = 66;
 p1.m_b = 44;
 Person p2;
 p2.m_a = 6;
 p2.m_b = 4;
 Person p3;
 //函數(shù)原型調(diào)用
 p3 = operator+(p1,p2);
 //簡便調(diào)用
 //p3 = p1 + p2;
 cout << "p3.m_a:" << p3.m_a << endl;
 cout << "p3.m_b:" << p3.m_b << endl;
}
int main()
{
 test01();
 system("pause");
 return 0;
}

注意兩種調(diào)用方式

通過函數(shù)原型調(diào)用

p3 = operator+(p1,p2);

簡便調(diào)用

p3 = p1 + p2;

運算符重載發(fā)生函數(shù)重載

運算符重載可以發(fā)生函數(shù)重載：Person+int等等

#include<iostream>
using namespace std;
class Person
{
public:
 int m_a;
 int m_b;
};
//通過全局函數(shù)實現(xiàn)重載
Person operator+ (Person& p1, int num)
{
 //創(chuàng)建一個臨時變量
 Person temp;
 temp.m_a = p1.m_a + num;
 temp.m_b = p1.m_b + num;
 return temp;
}
void test01()
{
 Person p1;
 p1.m_a = 66;
 p1.m_b = 44;
 Person p2;
 p2.m_a = 6;
 p2.m_b = 4;
 Person p3;
 //函數(shù)原型調(diào)用
 //p3 = operator+(p1,55);
 //簡便調(diào)用
 p3 = p1 + 55;
 cout << "p3.m_a:" << p3.m_a << endl;
 cout << "p3.m_b:" << p3.m_b << endl;
}
int main()
{
 test01();
 system("pause");
 return 0;
}

調(diào)用方法和定義方法與上面相同，不再多余贅述

總結(jié)

1、系統(tǒng)內(nèi)置數(shù)據(jù)類型的表達式不可改變

2、不要濫用運算符重載

左移運算符

不利用成員函數(shù)重載左移運算符

沒有具體演示，因為報錯，我也沒寫出來

下面通過全局函數(shù)實現(xiàn)

#include<iostream>
using namespace std;
class Person
{
public:
 int m_a;
 int m_b;
 
};
ostream& operator<<(ostream& cout,Person&p)
{
 cout << "p.m_a=" <<p. m_a << " p.m_b=" <<p. m_b << endl;
 return cout;
}
void test01()
{
 Person p1;
 p1.m_a = 44;
 p1.m_b = 66;
 cout << p1 << endl;
}
int main()
{
 test01();
 system("pause");
 return 0;
}

因為要實現(xiàn)鏈式，實現(xiàn)追加，所以返回值必須是ostream

總結(jié)

配合友元實現(xiàn)自定義輸出類型

遞增運算符重載

遞增運算符重載

#include<iostream>
using namespace std;
class myInt
{
 friend ostream& operator<<(ostream& cout, myInt num);
public:
 myInt()
 {
 this->m_a = 0;
 }
 //前置++運算符重載
 myInt& operator++()//返回引用是為了一直對一個數(shù)據(jù)進行遞增，否則函數(shù)默認返回一個新的數(shù)
 {
 //先進行++
 m_a++;
 //然后返回自身
 return *this;
 }
 //后置++運算符重載
 myInt operator++(int)//int表示占位參數(shù)，用于區(qū)分前置后置參數(shù)
 {
 //先記錄當前的值
 myInt temp=*this;
 //再遞增
 m_a++;
 //然后返回記錄的值
 return temp;
 }
private:
 int m_a; 
};
//左移運算符重載
ostream& operator<<(ostream& cout, myInt num)
{
 cout << num.m_a;
 return cout;
}
void test01()
{
 myInt myint;
 cout << myint << endl;
 cout << ++myint << endl;
 cout << myint << endl;

}
int main()
{
 test01();
 system("pause");
 return 0;
}

賦值運算符重載

#include<iostream>
using namespace std;
class Person
{
public:
 Person(int num)//將數(shù)據(jù)開辟到堆區(qū)
 {
 m_a = new int(num);
 }
 ~Person()
 {
 if (m_a != NULL)
 {
  delete m_a;
  m_a = NULL;
 }
 }
 //重載賦值運算符
 Person& operator=(Person &p)//返回值用Person返回本身，可執(zhí)行連等
 {
 //先判斷是否有屬性在堆區(qū)，如果有先釋放干凈
 if (m_a != NULL)
 {
  delete m_a;
  m_a = NULL;
 }
 m_a = new int(*p.m_a);
 return *this;
 }
 int* m_a;
 
};
void test01()
{
 Person p1(18);
 Person p2(209);
 Person p3(9);
 p2 = p1 = p3;
 cout << *p1.m_a << endl;
 cout << *p2.m_a << endl;
 cout << *p3.m_a << endl;
}
int main()
{
 test01();
 system("pause");
 return 0;
}

關(guān)系運算符重載

#include<iostream>
using namespace std;
#include<string>
class Person
{
public:
 
 Person(string name, int age)
 {
 this->age = age;
 this->name = name;
 }
 bool operator==(Person& p)
 {
 if (this->age == p.age && this->name == p.name)
 {
  return true;
 }
 else {
  return false;
 }
 }
 bool operator!=(Person& p)
 {
 if (this->age == p.age && this->name == p.name)
 {
  return false;
 }
 else {
  return true;
 }
 }
 string name;
 int age;

 
};
void test01()
{
 Person p1("gouride", 19);
 Person p2("gouride", 19);
 if (p1 == p2) {
 cout << "p1和p2相同" << endl;
 }
 else {
 cout << "p1和p2不相同" << endl;
 }
 if (p1 != p2) {
 cout << "p1和p2不相同" << endl;
 }
 else {
 cout << "p1和p2相同" << endl;
 }
}
int main()
{
 test01();
 system("pause");
 return 0;
}

函數(shù)調(diào)用重載

仿函數(shù)

#include<iostream>
using namespace std;
#include<string>
class Myprint
{
public:
 void operator()(string name)
 {
 cout << name << endl;
 }
 int operator()(int a,int b)
 {
 return a + b;
 }
};
void test01()
{
 
 Myprint myprint;
 myprint("測試");
 //匿名對象調(diào)用
 cout << Myprint()(4,6) << endl;
}
int main()
{
 test01();
 system("pause");
 return 0;
}