网易云课堂_C++程序设计入门(下)_第7单元：出入虽同趣，所向各有宜 – 文件输入和输出_第7单元 - 作业1：OJ编程

#include <iostream>
#include <limits>

using namespace std;

class Screen {
private:
	//----补充多个数据域成员

	// 在Screen类中获取/释放图形窗口资源，是一种RAII方法
	//   关于RAII，可以参见异常处理单元的材料
	unsigned int width;
	unsigned int height;
	static Screen *instance;

	Screen(unsigned int width, unsigned int height) {
		// 如果启用了图形库，则将初始化图形模式的函数置于此处
		// initgraph(width_, height_);
		this->width = width;
		this->height = height;
	};
	~Screen() {
		// 如果启用了图形库，则将关闭图形模式的函数置于此处
		// closegraph();
		delete instance;
		instance = NULL;
	}

public:
	//----补充 getWidth() 与 getHeight() 函数，
	unsigned int getWidth()
	{
		return width;
	}

	unsigned int getHeight()
	{
		return height;
	}

	static Screen* getInstance(unsigned int width = 640, unsigned int height = 480) {
		// 单例模式
		//----补充函数体
		Screen* ret = instance;
		if (ret == NULL)
		{
			instance = new Screen(width, height);
			ret = instance;
		}

		return ret;
	}
};

Screen* Screen::instance = 0;
//----补充Screen类的特殊数据成员初始化语句

int main() {
	int width, height;
	Screen* screen = 0;

	cin >> width >> height;
	screen = Screen::getInstance(width, height);
	screen = Screen::getInstance();

	cout << screen->getWidth() << " " <<
		screen->getHeight() << endl;

	// GCC及VC编译器在调试模式下会暂停，便于查看运行结果
#if ( defined(__DEBUG__) || defined(_DEBUG) )
	cin.ignore(numeric_limits<streamsize>::max(), ‘\n‘);
	cin.get();
#endif

	return 0;
}