定义一个矩形类，有长、宽两个属性，有成员函数计算矩形的面积

解：

#include <iostream.h>
class Rectangle
{
public:
Rectangle(float len, float width)
{
Length = len;
Width = width;
}
~Rectangle(){};
float GetArea() { return Length * Width; }
float GetLength() { return Length; }
float GetWidth() { return Width; }
private:
float Length;
float Width;
};
void main()
{
float length, width;
cout << "请输入矩形的长度：";
cin >> length;
cout << "请输入矩形的宽度：";
cin >> width;
Rectangle r(length, width);
cout << "长为" << length << "宽为" << width << "的矩形的面积为："
<< r.GetArea () << endl;
}