#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");
     }

楼主貌似以前学过Java。
类的声明后边要有;
使用构造函数要加括号：
Rectangle * pRect = new Rectangle();
主要就这两个问题吧