#include<iostream>
#include<string>
using namespace std;
class book
{
public:
	book(){}
	book(string name,int num):name(name),num(num){}
	void print()
	{
		cout << this->name << ":" << this->num << endl;
	}
	//重载函数
	friend book operator+(book object1, book object2);
	//类的成员函数的方式重载
	//减法
	book operator-(book object)//this:BOOK object:BO
	{
		return book(this->name, this->num - object.num);
	}
	string& get_name()
	{
		return name;
	}
	int& get_num()
	{
		return num;
	}
protected:
	string name;
	int num;
};
//友元重载
book operator+(book object1, book object2)
{
	return book(object1.name+ object2.name, object1.num+ object2.num);
}
int main()
{
	book BO("三国", 201);
	book BOOK("水浒传", 202);
	//重载函数隐式调用
	book object = BO + BOOK;	//所有重载实质都是函数调用
	//重载函数的显式调用
	//operator+解析为函数名
	book novel = operator+(BO, BOOK);//需要两个参数是因为是在类外
	book BOO = BOOK - BO;
	BOO.print();
	object.print();//this代表object
	novel.print();//this代表novel
	book BOOK1 = BO.operator-(BOOK);
	BOOK1.print();
	return 0;
}

 特殊运算符

#include<iostream>
#include<string>
using namespace std;
class Num
{
public:
	Num(){}
	Num(int iNum=0):iNum(iNum){}
	Num operator++(int)   //后置的++或者--需要加一个无效参数,eg:int
	{
		return Num(this->iNum++);
	}
	Num operator++()   //前置的++
	{
		return Num(++this->iNum);
	}
	void print()
	{
		cout << iNum << endl;
	}
	int& get_num()
	{
		return iNum;
	}
protected:
	int iNum;
};

int main()
{
	Num a(1);
	Num b = a++;//a.operator++()

	b.print();//1
	a.print();//2
	Num d = ++a;//3
	a.print();//3
	d.print();//3
	return 0;
}

operator隐式转换

#include<iostream>
using namespace std;
class book
{
public:
	book(string name=" ",int num=0):name(name),num(num){}
	void print()
	{
		cout << name << "\t" << num << endl;
	}
	//operator 要转的类型() { return 返回相应类型的数据;};
	operator int()
	{
		return this->num;
	}
protected:
	string name;
	int num;
};
int main()
{
	book object("三国",201);
	object.print(); 
	//赋值操作的隐式转换
	int sum = object;
	cout << sum << endl;
	return 0;
}