Question

I was trying to implement a Piece Table data structure using Linked Lists in a project of mine. My project has 7 files, as follows:

• LinkedList.cpp

• LinkedList.h

• Node.cpp

• Node.h

• PieceTable.h

• PieceTable.cpp

• Main.cpp

So the problem here is that in my class PieceTable, I have a data member of type LinkedList. Everything was fine till yesterday. I had built the project multiple times and it was working good. Today, in the morning, I added 1 function to LinkedList and another to PieceTable. When I tried top build it, the compiler says:

1>c:\users\devjeet\documents\visual studio 2010\projects\piece table\piece table\piecetable.h(33): error C2079: 'PieceTable::dList' uses undefined class 'LinkedList'

dList is the name of the class member of type LinkedList. I even put a forward class declaration, upon which the compiler said something that meant :

LinkedList is an undefined class

Here are the header files :

PieceTable :

#ifndef PIECETABLE_H
#define PIECETABLE_H
#include <Windows.h>
#include <iostream>
#include "LinkedList.h"
#include "Node.h"

class LinkedList;

using namespace std;

class PieceTable
{
public:
    PieceTable(void);
    ~PieceTable(void);

    //buffer realated functions
    void setBuffer(char buffer[]);

    //printing functions
    void printBuffer();
    void printTable();


    //text insertion functions 
    void insertTextAfterPosition(char text, const int& position);
private:
    LinkedList dList;
    char* originalBuffer;
    char* editBuffer;
    int bufferLength;
    int editBufferCounter;

};
#endif

LinkedList :

#ifndef LINKEDLIST_H
#define LINKEDLIST_H
#include "Node.h"
#include "PieceTable.h"

class Node;

class LinkedList
{
public:
    LinkedList();
    ~LinkedList();

    bool isEmpty() const;

    //functions that deal with getting nodes
    Node* getNodeAtPosition(const int& position) const;
    Node* getFront() const;
    Node* getBack() const;
    Node* getHead()const;
    Node* getTail()const;
    Node* getNodeFromOffset(const int& offset) const;

    //functions that deal with adding nodes
    void append(const int offset, const int& length,const bool descriptor);
    void add(Node* node, const int offset, const int& length,const bool descroptor);                                //adds a node after the given node
    void insertNodeAfterPosition(const int offset, const int& length,const bool descriptor, const int& position);

    //function concerned with deletion
    void removeNode(Node* node);
    void deleteNodeAtPosition(const int& position);
    void removeBack();
    void removeFront();
    void emptyList();

    //debugging functions
    void printNodes();
private:
    Node* head;
    Node* tail;
};

#endif

Note that the problem occurs whether I use #pragma once or #ifndef/#endif

Thanks,

Devjeet

Answer 1

This is a fairly straight-forward circular inclusion: piecetable.h includes linkedlist.h, and linkedlist.h erroneously includes piecetable.h. I believe you can remove the second inclusion, and you can remove the forward declaration of class LinkedList from piecetable.h.