设计一个矩形类Rectangle 数据成员： length(私有),width(私有)和color（公有） 成员函数：（均为公有） SetLengthWidth,GetLengthWi GetArea, ShowColor,SetColor 并设计一个主函数来测试你所编写的类。

#include <iostream>
using namespace std;

class Rectangle {
private:
    double length;
    double width;
public:
    string color;
    void SetLengthWidth(double l, double w) {
        length = l;
        width = w;
    }
    double GetLength() {
        return length;
    }
    double GetWidth() {
        return width;
    }
    double GetArea() {
        return length * width;
    }
    void ShowColor() {
        cout << "Color: " << color << endl;
    }
    void SetColor(string c) {
        color = c;
    }
};

int main() {
    Rectangle rect;
    rect.SetLengthWidth(4.5, 3.2);
    rect.SetColor("red");
    rect.ShowColor();
    cout << "Length: " << rect.GetLength() << endl;
    cout << "Width: " << rect.GetWidth() << endl;
    cout << "Area: " << rect.GetArea() << endl;
    return 0;
}