C++运算符重载

1.加法运算符重载

1.1成员函数重载+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;
	}
public:
	int m_A;
	int m_B;
};

成员函数重载本质调用
Person p3 = p1.operator+(p2);

void test01()
{
	Person p1;
	p1.m_A = 10;
	p1.m_B = 20;

	Person p2;
	p2.m_A = 30;
	p2.m_B = 40;
	
	Person p3 = p1 + p2;

	cout << "p3.m_A = " << p3.m_A << endl;
	cout << "p3.m_B = " << p3.m_B << endl;
}

1.2全局函数重载+号

class Person
{
public:
	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;
}

全局函数重载本质调用
Person p3 = operator+(p1,p2);

void test01()
{
	Person p1;
	p1.m_A = 10;
	p1.m_B = 20;

	Person p2;
	p2.m_A = 30;
	p2.m_B = 40;

	Person p3 = p1 + p2;

	cout << "p3.m_A = " << p3.m_A << endl;
	cout << "p3.m_B = " << p3.m_B << endl;
}

1.3函数重载

class Person
{
public:
	int m_A;
	int m_B;
};

函数重载的版本

Person operator+(Person& p1, int num)
{
	Person temp;
	temp.m_A = p1.m_A + num;
	temp.m_B = p1.m_B + num;
	return temp;
}

运算符重载，也可以发生函数重载

void test01()
{
	Person p1;
	p1.m_A = 10;
	p1.m_B = 20;

	Person p4 = p1 + 10;	//Person +int

	cout << "p4.m_A = " << p4.m_A << endl;
	cout << "p4.m_B = " << p4.m_B << endl;
}

2.左移运算符重载

利用成员函数重 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<<(Person& p){}

//左移运算符重载
class Person
{
public:
	int m_A;
	int m_B;
};

只能利用全局函数重载左移运算符
格式：遇到ostream<<Person时，才会调用重载函数
类比：
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 p3 = p1 + p2;
}

返回的out再与<<endl;结合：out<<endl;组成链式结合

ostream &operator<<(ostream &cout,Person &p)	//本质opeartor << (cout, p)	简化 cout<< p
{
	cout << "m_A= " << p.m_A << "m_B= " << p.m_B;
	return cout;
}

void test01()
{
	Person p;
	p.m_A = 10;
	p.m_B = 10;

	cout << p <<endl;
}