[] In the exemplary overload C ++ class.

#include <iostream>

// overloading "operator [] " inside class

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

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

	~Rectangle() {};
	int& operator[] (const size_t i);

public:
	int width;
	int height;
};


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

int & 
Rectangle::operator[](const size_t i)
{
	if (i == 0)
		return width;
	else
		return height;
}


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

std::ostream&
operator<< (std::ostream& os, const Rectangle& rec)
{
	os << rec.width << ", " << rec.height;
	return  os;

}

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

int main ()
{
	Rectangle a(40, 10);
	
	std::cout
		<< "w = " << a[0] << std::endl		// 输出 40
		<< "h = " << a[1] << std::endl		// 输出 10
		;
	

	return 0;
}