第二十章友元类与嵌套类 2嵌套类 简单

//第二十章友元类与嵌套类 2嵌套类
//C++不光可以包含对像，还可以包含类，我们把C++所包含的类叫做嵌套类
//不过，包含对像与嵌套类有着本质的不同，包含对像只是将另一个类的对像作为该类的成员，而嵌套类似则是在该类中定义了一种新的类型，这个类型只能在该类中使用

#include <iostream>
using namespace std;
class rectangle
{
public:
	//这里直接在rectangel的公有部分定义了一个类
	class point
	{
	public:
		void setX(int x){ itsx = x;}
		void setY(int y){ itsy = y;}
		int getx()const{ return itsx;}
		int gety()const{ return itsy;}
	private:
		int itsx; //x
		int itsy; //y
	};
	point GetUpLeft()const{ return upleft; }
	point GetLowLeft()const{ return lowerleft;}
	point GetUpRight()const{ return upright;}
	point GetLowRight()const{ return lowerright;}

	//构造函数,在下面定义
	rectangle(int top, int left, int bottom, int right);
	~rectangle(){}

	//分别取得top left right bottom的值
	int GetTop()const{ return Top;}
	int GetLeft()const{ return Left;}
	int GetBottom()const{ return Bottom; }
	int GetRight()const{ return Right;}

	//设置upleft lowleft upright lowright的值
	void SetUpLeft(){ upleft.setX(Left); upleft.setY(Top); }
	void SetLowLeft(){ lowerleft.setX(Left); lowerleft.setY(Bottom); }
	void SetUpRight(){ upright.setX(Right); upright.setY(Top); }
	void SetLowRight(){ lowerright.setX(Right); lowerright.setY(Bottom); }
	
	//设置 top left right bottom
	void SetTop(int a){ Top = a;}
	void SetLeft(int a){ Left = a;}
	void SetRight(int a){ Right = a;}
	void SetBottom(int a){ Bottom = a;}

	int GetArea()const{
	    int width = Right - Left;
		int height = Bottom - Top;
		return (width*height);	
	}



private:
	//这四个变量的类型分别是point类型的
	point upleft;
	point lowerleft;
	point upright;
	point lowerright;

	//上下左右
	int Top;
	int Left;
	int Bottom;
	int Right;
};

rectangle::rectangle(int top, int left, int bottom, int right)
{
    Top = top;
	Left = left;
	Bottom = bottom;
	Right = right;

	upleft.setX(Left);
	upleft.setY(Top);

	upright.setX(Right);
	upright.setY(Top);

	lowerright.setX(Right);
	lowerright.setY(Bottom);

	lowerleft.setX(Left);
	lowerleft.setY(Bottom);
}

class point
{
public:
	int GetArea(rectangle &rec){ return rec.GetArea(); }
};
int main()
{
	rectangle date(40,50,60,80);
	cout<<"左边为:"<<date.GetLeft()<<endl;
	cout<<"下边为:"<<date.GetBottom()<<endl;
	cout<<"左上的x坐标为:"<<date.GetLowLeft().getx()<<endl;
	cout<<"左上的y坐标为:"<<date.GetLowLeft().gety()<<endl;
	cout<<"矩形面积为:"<<date.GetArea()<<endl;
	cout<<"重新设置left和Bottom值"<<endl;
	
	date.SetLeft(0);
	date.SetBottom(100);
	date.SetLowLeft();
	cout<<"左边为:"<<date.GetLeft()<<endl;
	cout<<"下边为:"<<date.GetBottom()<<endl;
	cout<<"左上的x坐标为:"<<date.GetLowLeft().getx()<<endl;
	cout<<"左上的y坐标为:"<<date.GetLowLeft().gety()<<endl;

	point pt;
	cout<<"矩形面积为:"<<pt.GetArea(date)<<endl;
    return 0;
}