思维导图：

 2、自己封装一个矩形类(Rect)，

拥有私有属性：宽度(width)、高度(height)，

定义公有成员函数初始化函数:void init(int w, int h)

更改宽度的函数:set_w(int w)更改高度的函数:set_h(int h)

输出该矩形的周长和面积函数:void show()
 

#include <iostream>using namespace std;class Rect
{protected:private:int width;int height;
public:void init(int w,int h){width = w;height = h;}void set_w(int w){width = w;}void set_h(int h){height = h;}void show(){cout << "周长 = " << 2 * ( width + height ) << endl;cout << "面积 = " << width * height << endl;}};int main()
{Rect rec;rec.init(3,4);rec.show();rec.set_h(6);rec.show();rec.set_w(5);rec.show();return 0;
}