C++学习笔记day15-函数运算符重载

1、加号运算符重载

#include<iostream>
using namespace std;

//加号运算符重载

//1、成员函数重载+号

//2、全局函数重载+号
class Person
{
public:

//1、成员函数重载+号
/*Person operator+(Person &p)
{
Person temp;
temp.m_A = this->m_A + p.m_A;
temp.m_B = this->m_B + p.m_B;
return temp;

}*/
int m_A;
int m_B;

};
Person operator+(Person &p1, Person &p2)
{
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 = 10;
p1.m_B = 10;
Person p2;
p2.m_A = 10;
p2.m_B = 10;

//成员函数本质调用
/*Person p3 = p1.operator+(p2);
*/
//全局函数重载本质调用
Person p3 = operator+(p1, p2);
//Person 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;
}

2、左移运算符重载

#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)
{
m_A = a;
m_B = b;
}
private:

//利用成员函数重载 左移运算符  p.operator<<(cout) 简化版本 p<<cout
//不会利用成员函数重载<<运算符，因为无法实现cout 在左侧
/*void operator<<(cout)
{

}*/
int m_A;
int m_B;

};

//只能利用全局函数重载左移运算符
ostream &  operator<<(ostream &cout,Person &p)//本质 operator<<(cout,p) 简化cout<<p
{
cout << "m_A = " << p.m_A<<" " << "m_B=" << p.m_B;
return cout;
}
void test01()
{
Person p(10,10);
/*p.m_A = 10;
p.m_B = 10;*/

cout << p<<endl;

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

3、递增运算符重载

#include<iostream>
using namespace std;

//重载递增运算符

//自定义整型

class MyInteger
{
friend ostream &  operator<<(ostream &cout, 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++()
{
//先进行++运算
m_Num++;

//再将自身做返回
return *this;
}
//MyInteger operator++(int) int代表占位参数，可以区分前置和后置递增
MyInteger operator++(int)
{
//先 记录当时结果
MyInteger temp = *this;
//后 递增
m_Num++;
//最后将记录结果做返回
return temp;
}

//重载后置++运算符

private:
int m_Num;
};

void test01()
{
MyInteger myint;
cout << ++(++myint) << endl;
cout << myint << endl;
}

void test02()
{
MyInteger myint;
cout << myint++ << endl;
cout << myint << endl;
}
//重载<<运算符
ostream& operator<<(ostream& cout, MyInteger myint)
{
cout << myint.m_Num;
return cout;
}
int main()
{

//test01();
test02();
system("pause");

return 0;
}

4、赋值运算符重载

#include<iostream>
using namespace std;

//赋值运算符重载

class Person
{
public:
Person(int age)
{
m_Age=new int(age);

}

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

//重载 赋值运算符
Person& operator=(Person &p)
{
//编译器是提供浅拷贝
//m_Age =p.m_Age;

//应该先判断是否有属性在堆区，如果有先释放干净，然后再深拷贝
if (m_Age != NULL)
{
delete m_Age;
m_Age = NULL;
}
m_Age = new int(*p.m_Age);
return *this;
}
int *m_Age;
};

void test01()
{
Person p1(18);
Person p2(20);
Person p3(30);
p3 = p2 = p1;
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();
system("pause");

return 0;
}

5、关系运算符重载

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

//重载关系运算符

class  Person
{
public:

Person(string name, int age)
{
m_Name = name;
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;
}
return false;
}
bool operator!=(Person &p)
{
if (this->m_Name == p.m_Name&&this->m_Age == p.m_Age)
{
return false;
}
return true;
}
string m_Name;
int m_Age;

};

void test01()
{
Person p1("Tom", 18);
Person p2("Tom", 18);
if (p1 == p2)
{
cout << "p1和p2是相等的" << endl;
}
else
{
cout << "p1和p2是不相等的" << endl;
}
}

int main()
{
test01();
system("pause");

return 0;
}

6、函数调用运算符重载

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

//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 test)
{
cout << test << endl;
}
};
void MyPrint02(string test)
{
cout << test << endl;
}

void test01()
{
MyPrint myPrint;
myPrint("Hello world");//由于使用起来非常类似于函数调用，因此称为仿函数
MyPrint02("hello world");
}

//仿函数非常灵活，没有固定写法
//加法类

class MyAdd
{
public:
int operator()(int num1,int num2)
{
return num1 + num2;
}
};
void test02()
{
MyAdd myadd;
int ret = myadd(100, 100);
cout << "ret= " << ret << endl;

//匿名函数对象
cout << MyAdd()(100, 100) << endl;
}
int main()
{
//test01();
test02();
system("pause");
return 0;
}