listwr01.cpp

teach yourself C++ in 21 days 第五版

// **************************************************
//
// Title:       Week 2 in Review
//
// File:       Week2
//
// Description:   Provide a linked list demonstration program
//
// Classes:      PART - holds part numbers and potentially other
//                     information about parts
//
//               PartNode - acts as a node in a PartsList
//
//               PartsList - provides the mechanisms for 
//                           a linked list of parts
//
//
// **************************************************

 #include <iostream>
 using namespace std;



 // **************** Part ************

 // Abstract base class of parts
 class Part
 {
   public:
     Part():itsPartNumber(1) {}
     Part(int PartNumber):itsPartNumber(PartNumber){}
     virtual ~Part(){};
     int GetPartNumber() const { return itsPartNumber; }
     virtual void Display() const =0;  // must be overridden
   private:
     int itsPartNumber;
 };

 // implementation of pure virtual function so that
 // derived classes can chain up
 void Part::Display() const
 {
     cout << "\nPart Number: " << itsPartNumber << endl;
 }

 // **************** Car Part ************

 class CarPart : public Part
 {
   public:
     CarPart():itsModelYear(94){}
     CarPart(int year, int partNumber);
     virtual void Display() const
    {
       Part::Display(); cout << "Model Year: ";
       cout << itsModelYear << endl;
    }
   private:
     int itsModelYear;
 };

 CarPart::CarPart(int year, int partNumber):
    itsModelYear(year),
    Part(partNumber)
 {}


 // **************** AirPlane Part ************

 class AirPlanePart : public Part
 {
   public:
     AirPlanePart():itsEngineNumber(1){};
     AirPlanePart(int EngineNumber, int PartNumber);
     virtual void Display() const
    {
       Part::Display(); cout << "Engine No.: ";
       cout << itsEngineNumber << endl;
    }
   private:
     int itsEngineNumber;
 };

 AirPlanePart::AirPlanePart(int EngineNumber, int PartNumber):
    itsEngineNumber(EngineNumber),
    Part(PartNumber)
 {}

 // **************** Part Node ************
 class PartNode
 {
   public:
     PartNode (Part*);
     ~PartNode();
     void SetNext(PartNode * node) { itsNext = node; }
     PartNode * GetNext() const;
     Part * GetPart() const;
   private:
     Part *itsPart;
     PartNode * itsNext;
  };

  // PartNode Implementations...

  PartNode::PartNode(Part* pPart):
  itsPart(pPart),
  itsNext(0)
  {}

  PartNode::~PartNode()
  {
     delete itsPart;
     itsPart = 0;
     delete itsNext;
     itsNext = 0;
  }

  // Returns NULL if no next PartNode
  PartNode * PartNode::GetNext() const
  {
     return itsNext;
  }

  Part * PartNode::GetPart() const
  {
     if (itsPart)
        return itsPart;
     else
        return NULL; //error
  }

  // **************** Part List ************
  class PartsList
  {
    public:
      PartsList();
      ~PartsList();
      // needs copy constructor and operator equals!
      Part*      Find(int & position, int PartNumber)  const;
      int        GetCount() const { return itsCount; }
      Part*      GetFirst() const;
      void       Insert(Part *);
      void       Iterate() const;
      Part*      operator[](int) const;
    private:
      PartNode * pHead;
      int itsCount;
  };

  // Implementations for Lists...

  PartsList::PartsList():
     pHead(0),
     itsCount(0)
     {}

  PartsList::~PartsList()
  {
     delete pHead;
  }

  Part*   PartsList::GetFirst() const
  {
     if (pHead)
        return pHead->GetPart();
     else
        return NULL;  // error catch here
  }

  Part *  PartsList::operator[](int offSet) const
  {
     PartNode* pNode = pHead;

     if (!pHead)
        return NULL; // error catch here

     if (offSet > itsCount)
        return NULL; // error

     for (int i=0;i<offSet; i++)
        pNode = pNode->GetNext();

    return   pNode->GetPart();
  }

  Part*   PartsList::Find(int & position, int PartNumber)  const
  {
     PartNode * pNode = 0;
     for (pNode = pHead, position = 0;
           pNode!=NULL;
           pNode = pNode->GetNext(), position++)
     {
        if (pNode->GetPart()->GetPartNumber() == PartNumber)
           break;
     }
     if (pNode == NULL)
        return NULL;
     else
        return pNode->GetPart();
  }

  void PartsList::Iterate() const
  {
     if (!pHead)
        return;
     PartNode* pNode = pHead;
     do
        pNode->GetPart()->Display();
     while (pNode = pNode->GetNext());
  }

  void PartsList::Insert(Part* pPart)
  {
     PartNode * pNode = new PartNode(pPart);
     PartNode * pCurrent = pHead;
     PartNode * pNext = 0;

     int New =  pPart->GetPartNumber();
     int Next = 0;
     itsCount++;

     if (!pHead)
     {
        pHead = pNode;
        return;
     }

     // if this one is smaller than head
     // this one is the new head
     if (pHead->GetPart()->GetPartNumber() > New)
     {
        pNode->SetNext(pHead);
        pHead = pNode;
        return;
     }

     for (;;)
     {
        // if there is no next, append this new one
        if (!pCurrent->GetNext())
        {
           pCurrent->SetNext(pNode);
           return;
        }

        // if this goes after this one and before the next
        // then insert it here, otherwise get the next
        pNext = pCurrent->GetNext();
        Next = pNext->GetPart()->GetPartNumber();
        if (Next > New)
        {
           pCurrent->SetNext(pNode);
           pNode->SetNext(pNext);
           return;
        }
        pCurrent = pNext;
     }
  }

  int main()
  {
     // PartsList&pl = PartsList::GetGlobalPartsList();
     PartsList pl;

     Part * pPart = 0;
     int PartNumber;
     int value;
     int choice = 99;

     while (choice != 0)
     {
        cout << "(0)Quit (1)Car (2)Plane: ";
        cin >> choice;

        if (choice != 0 )
        {  
            cout << "New PartNumber?: ";
            cin >>  PartNumber;

            if (choice == 1)
            {
               cout << "Model Year?: ";
               cin >> value;
               pPart = new CarPart(value,PartNumber);
            }
            else
            {
               cout << "Engine Number?: ";
               cin >> value;
               pPart = new AirPlanePart(value,PartNumber);
            }

            pl.Insert(pPart);
        }
     }
     pl.Iterate();
     return 0;
  }