#include <iostream>
using namespace std;

class Rectangle
{
      public:
               Rectangle();
               ~Rectangle();
               //void SetLength(int length){itsLength = length;}
               //int GetLength() const { return itsLength;}
               void SetWidth(int width){ itsWidth = width;}
               int GetWidth() const { return itsWidth;}
                             
      private:
                //int itsLength;
                int itsWidth;
}
Rectangle::Rectangle()
{
      itsWidth = 5;
                      }
              //itsLength = 6;
              

Rectangle::~Rectangle()
{}
int main()
{
    Rectangle * pRect = new Rectangle;
    const Rectangle * pConstRect = new Rectangle;
    Rectangle * const pConstPtr = new Rectangle;
   
    cout << "pRect width: " << pRect->GetWidth() << "feet\n";
    cout << "pConstRect width: " << pConstRect->GetWidth() << " feet\n";
    cout << "pConstPtr width. " << pConstPtr->GetWidth() << " feet\n";
    pRect -> SetWidth(10);
    pConstRect -> SetWidth(9);
    pConstPtr -> SetWidth(10);
   
    cout << "pRect width: " << pRect->GetWidth() << "feet\n";
    cout << "pConstRect width: " << pConstRect->GetWidth() << " feet\n";
    cout << "pConstPtr width. " << pConstPtr->GetWidth() << " feet\n";
    system("pause");
     }

首先 类声明后要加 ";"
主函数后要有返回值 return 0;
const Rectangle * pConstRect = new Rectangle; 是指向常量的指针 不能赋值

pConstRect -> SetWidth(9);
既然是指向常量的指针,那么是不能修改常量的属性的
#include <iostream>
using namespace std;

class Rectangle
{
public:
     Rectangle();
     ~Rectangle();
               //void SetLength(int length){itsLength = length;}
               //int GetLength() const { return itsLength;}
     void SetWidth(int width){ itsWidth = width;}
               int GetWidth() const { return itsWidth;}
                             
      private:
                //int itsLength;
     int itsWidth;
};
Rectangle::Rectangle()
{
      itsWidth = 5;
}
              //itsLength = 6;
              

Rectangle::~Rectangle()
{}
int main()
{
    Rectangle * pRect = new Rectangle;
    const Rectangle * pConstRect = new Rectangle;
    Rectangle * const pConstPtr = new Rectangle;
   
    cout << "pRect width: " << pRect->GetWidth() << "feet\n";
    cout << "pConstRect width: " << pConstRect->GetWidth() << " feet\n";
    cout << "pConstPtr width. " << pConstPtr->GetWidth() << " feet\n";
    pRect -> SetWidth(10);
    //pConstRect -> SetWidth(9);
    pConstPtr -> SetWidth(10);
   
    cout << "pRect width: " << pRect->GetWidth() << "feet\n";
    cout << "pConstRect width: " << pConstRect->GetWidth() << " feet\n";
    cout << "pConstPtr width. " << pConstPtr->GetWidth() << " feet\n";
    system("pause");
    return 0;
}

另外
Rectangle * pRect = new Rectangle;应该写成

Rectangle * pRect；
pRect = new Rectangle;

ls
这两种 有什么区别吗?