C++类和对象-C++运算符重载-＞加号运算符重载、左移运算符重载、递增运算符重载、赋值运算符重载、关系运算符重载、函数调用运算符重载

#include<iostream>
using namespace std;

//加号运算符重载

class Person {
public:
   Person() {};
   Person(int a, int b)
   {
       this->m_A = a;
       this->m_B = b;
   }
   //1.成员函数实现 + 号运算符重载
   Person operator+(const Person& p) {
       Person temp;
       temp.m_A = this->m_A + p.m_A;
       temp.m_B = this->m_B + p.m_B;
       return temp;
   }

public:
int m_A;
int m_B;
};

//2.全局函数实现 + 号运算符重载
//Person operator+(const Person& p1, const Person& p2) {
//   Person temp(0, 0);
//   temp.m_A = p1.m_A + p2.m_A;
//   temp.m_B = p1.m_B + p2.m_B;
//   return temp;
//}

//运算符重载可以发生函数重载
Person operator+(const Person& p2, int val)
{
   Person temp;
   temp.m_A = p2.m_A + val;
   temp.m_B = p2.m_B + val;
   return temp;
}

void test() {

Person p1(10, 10);
Person p2(20, 20);

   //成员函数重载本质调用
   Person p3 = p2 + p1; //相当于 p2.operaor+(p1)
   cout << "mA:" << p3.m_A << " mB:" << p3.m_B << endl;

   //全局函数重载本质调用
   Person p4 = p1 + p2; //相当于 operator+(p1,p2)
   cout << "mA:" << p4.m_A << " mB:" << p4.m_B << endl;

   //运算符重载也可以发生函数重载
   Person p5 = p3 + 10; //相当于 operator+(p3,10)
   cout << "mA:" << p5.m_A << " mB:" << p5.m_B << endl;

}

int main() {

test();

system("pause");

return 0;
}

总结1：对于内置的数据类型的表达式的的运算符是不可能改变的

总结2：不要滥用运算符重载

#include<iostream>
using namespace std;

//左移运算符重载
class Person
{
friend ostream& operator<<(ostream& cout, Person& p);

public:

   Person(int a, int b)
   {
       this->m_A = a;
       this->m_B = b;
   }
   //利用成员函数重载左移运算符
   //成员函数实现不了 p << cout 不是我们想要的效果
   //void operator<<(Person& p){
   //}

private:
int m_A;
int m_B;
};

//只能利用全局函数重载实现左移运算符
//ostream对象只能有一个
ostream& operator<<(ostream& cout, Person& p) //本质 operator<<(cout,p) 简化 cout<<p
{
cout << "a:" << p.m_A << " b:" << p.m_B;
return cout;
}

void test()
{
Person p1(10, 20);
cout << p1 << " hello world" << endl; //链式编程
}

int main()
{

test();

system("pause");

return 0;
}

总结：重载左移运算符配合友元可以实现输出自定义数据类型

#include<iostream>
using namespace std;
//重载递增运算符
//自定义整型
class MyInteger
{

friend ostream& operator<<(ostream& out, MyInteger myint);

public:
   MyInteger()
   {
       m_Num = 0;
   }
   //重载前置++运算符返回引用为了一直对一个数据进行递增操作
   MyInteger& operator++()
   {
       //先++
       m_Num++;
       //再返回
       return *this;
   }

   //重载后置++运算符
   //int代表占位参数，可以用于区分前置和后置递增
   MyInteger operator++(int)
   {
       //先记录当前结果
       MyInteger temp = *this; //记录当前本身的值，然后让本身的值加1，但是返回的是以前的值，达到先返回后++；
       //后递增
       m_Num++;
       //最后将记录结果做返回
       return temp;
   }

private:
int m_Num;
};

//重载<<运算符
ostream& operator<<(ostream& out, MyInteger myint)
{
out << myint.m_Num;
return out;
}

//前置++ 先++ 再返回
void test01()
{
   MyInteger myInt;
   cout << ++myInt << endl;
   cout << myInt << endl;
}

//后置++ 先返回再++
void test02()
{

   MyInteger myInt;
   cout << myInt++ << endl;
   cout << myInt << endl;
}

int main()
{

//test01();
test02();

system("pause");

return 0;
}

总结：前置递增返回引用，后置递增返回值

#include<iostream>
using namespace std;

//赋值运算符重载
class Person
{
public:

   Person(int age)
   {
       //将年龄数据开辟到堆区
       m_Age = new int(age);
   }

   //重载赋值运算符
   Person& operator=(Person &p)
   {
       //应该先判断是否有属性在堆区，如果有先释放感觉，然后再深拷贝
       if (m_Age != NULL)
       {
           delete m_Age;
           m_Age = NULL;
       }
       //编译器提供的代码是浅拷贝
       //m_Age = p.m_Age;

//提供深拷贝解决浅拷贝的问题
m_Age = new int(*p.m_Age);

       //返回对象自身
       return *this;
   }

   ~Person()
   {
       if (m_Age != NULL)
       {
           delete m_Age;
           m_Age = NULL;
       }
   }

//年龄的指针
int *m_Age;

};

void test01()
{
Person p1(18);

Person p2(20);

Person p3(30);

p3 = p2 = p1; //赋值操作

cout << "p1的年龄为：" << *p1.m_Age << endl;

cout << "p2的年龄为：" << *p2.m_Age << endl;

cout << "p3的年龄为：" << *p3.m_Age << endl;
}

int main() {

test01();

   //int a = 10;
   //int b = 20;
   //int c = 30;

   //c = b = a;
   //cout << "a = " << a << endl;
   //cout << "b = " << b << endl;
   //cout << "c = " << c << endl;

system("pause");

return 0;
}

#include<iostream>
using namespace std;
#include<string>

//重载关系运算符
class Person
{
public:
   Person(string name, int age)
   {
       this->m_Name = name;
       this->m_Age = age;
   };
   //重载 == 号
   bool operator==(Person & p)
   {
       if (this->m_Name == p.m_Name && this->m_Age == p.m_Age)
       {
           return true;
       }
       else
       {
           return false;
       }
   }

   bool operator!=(Person & p)
   {
       if (this->m_Name == p.m_Name && this->m_Age == p.m_Age)
       {
           return false;
       }
       else
       {
           return true;
       }
   }

string m_Name;
int m_Age;
};

void test01()
{
//int a = 0;
//int b = 0;

Person a("孙悟空", 18);
Person b("孙悟空", 18);

   if (a == b)
   {
       cout << "a和b相等" << endl;
   }
   else
   {
       cout << "a和b不相等" << endl;
   }

   if (a != b)
   {
       cout << "a和b不相等" << endl;
   }
   else
   {
       cout << "a和b相等" << endl;
   }
}

int main() {

test01();

system("pause");

return 0;
}

#include<iostream>
using namespace std;
#include<string>

//函数调用运算符重载
//打印输出类
class MyPrint
{
public:
   //重载函数调用运算符
   void operator()(string text)
   {
       cout << text << endl;
   }

};
void myFunc2(string text)
{
   cout << text << endl;
}
void test01()
{
   //重载的（）操作符也称为仿函数
   MyPrint myFunc;
   myFunc("hello world");//由于使用起来非常类似于函数调用，因此称为仿函数
   myFunc2("hello world");
}
//仿函数非常灵活，没有固定的写法
//加法类
class MyAdd
{
public:
   int operator()(int v1, int v2)
   {
       return v1 + v2;
   }
};