hw11_01.cpp

1、设计一个名为Rectangle2D的类，表示平面坐标下的一个矩形，这个类包括：
 四个double型数据成员：x, y, width, height，分别表示矩形中心坐标、宽和高
 一个不带形参的构造函数，用于创建缺省矩形：(x,y)=(0,0), width=height=1
  一个带形参的构造函数：Rectangle2D(double x, double y, double width, double height)
  成员函数doublegetAera()，返回矩形面积
 成员函数boolcontains(double x, double y)，当给定点(x,y)在矩形内时返回true，否则返回
false，如下图a)
  成员函数boolcontains(const Rectangle2D & r)，当给定矩形在当前矩形内时返回true，否则
返回false，如下图b)
  成员函数booloverlaps(const Rectangle2D & r)，当给定矩形与当前矩形有重叠时返回true，
否则返回false，如下图c)
实现这个类，并在主函数中测试：创建r1(2,2,5.4,4.8),r2(4,5,10.6,3.3) 和r3(3,5,2.2,5.5)，
输出r1的面积，以及r1.contains(3,3),r1.contains(r2) 和r1.overlaps(r3)的结果。

#include <iostream>
#include <cmath>

using namespace std;

class Rectangle2D
{
  public:
   Rectangle2D() : x(0.0), y(0.0), width(1.0), height(1.0) {};
   Rectangle2D(double x, double y, double width, double height);
   double getArea();
   bool contains(double x, double y);
   bool contains(const Rectangle2D & r);
   bool overlaps(const Rectangle2D & r);
  private:
   double x, y, width, height;
};

Rectangle2D::Rectangle2D(double x, double y, double width, double height){
   this->x = x;
   this->y = y;
   this->width = width;
   this->height = height;
   }
double Rectangle2D::getArea(){
   return width * height;
}
bool Rectangle2D::contains(double x, double y){
   return (x >= this->x && x <= this->x + this->width && y >= this->y && y <= this->y + this->height);
}
bool Rectangle2D::contains(const Rectangle2D &r)  {
   return fabs(r.x - x) <= (width - r.width) / 2 && fabs(r.y - y) <= (height - r.height) / 2;
}
bool Rectangle2D::overlaps(const Rectangle2D & r) {
   return fabs(x - r.x) < (width + r.width) / 2 && fabs(y - r.y) < (height + r.height) / 2;
};
int main()
{
   // 创建三个矩形
   Rectangle2D r1(2, 2, 5.4, 4.8);
   Rectangle2D r2(4, 5, 10.6, 3.3);
   Rectangle2D r3(3, 5, 2.2, 5.5);

   // 输出r1的面积
   cout << "r1's area: " << r1.getArea() << endl;

   // 测试contains和overlaps函数
   cout << "r1.contains(3, 3): " << r1.contains(3, 3) << endl;
   cout << "r1.contains(r2): " << r1.contains(r2) << endl;
   cout << "r1.overlaps(r3): " << r1.overlaps(r3) << endl;

   return 0;
}