C++ class内的==重载，判断相等，测试等于，重载示例。二元操作符

#include <iostream>

// overloading "operator == " inside class
// == 是二元操作符

//////////////////////////////////////////////////////////

class Rectangle
{
public:
	Rectangle(int w, int h)
		: width(w), height(h)
	{};

	~Rectangle() {};

	bool operator == (Rectangle& rec) const;

private:
	int width;
	int height;
};

//////////////////////////////////////////////////////////

bool Rectangle::operator==(Rectangle & rec) const//相同的class对象互为友元，所以可以访问private对象。== 是二元操作符，class内隐藏了this
{
	return this->height == rec.height
		&& this->width == rec.width;
}

// 等价于：
/*
bool Rectangle::operator==(Rectangle* this, Rectangle & rec) const
{
	return this->height == rec.height
		&& this->width == rec.width;
}
*/

//////////////////////////////////////////////////////////

int main()
{
	Rectangle a(40, 10);
	Rectangle b(40, 10);
	Rectangle c(4, 10);

	std::cout << (a == b) << std::endl;
	std::cout << (a == c) << std::endl;
	std::cout << (b == c) << std::endl;

	return 0;
}