CODEWITHSUNDEEP
c++linkerundefined-reference
Patrick LaChance
Patrick LaChance

Reputation: 19

Undefined reference to

I keep getting this error message every time I try to compile, and I cannot find out what the problem is. any help would be greatly appreciated:

C:\DOCUME~1\Patrick\LOCALS~1\Temp/ccL92mj9.o:main.cpp:(.txt+0x184): undefined reference to 'List::List()'
C:\DOCUME~1\Patrick\LOCALS~1\Temp/ccL92mj9.o:main.cpp:(.txt+0x184): undefined reference to 'List::add(int)'
collect2:  ld returned 1 exit status

code:

//List.h

#ifndef LIST_H
#define LIST_H

#include <exception>

//brief Definition of linked list class

class List
{
    public:

    /**
    \brief Exception for operating on empty list
    */  


    class Empty : public std::exception
 {
  public:
  virtual const char* what() const throw();
 };

    /**
    \brief Exception for invalid operations other than operating on an empty list
    */

    class InvalidOperation : public std::exception
 {
  public:
  virtual const char* what() const throw();
 };

    /**
    \brief Node within List
    */


    class Node
 {
  public: 
  /** data element stored in this node */
  int element;

  /** next node in list */
  Node* next;

  /** previous node in list */
  Node* previous;

  Node (int element);
  ~Node();

  void print() const;
  void printDebug() const;
 };


    List();
    ~List();

    void add(int element);
    void remove(int element);
    int first()const;
    int last()const;
    int removeFirst();
    int removeLast();
    bool isEmpty()const;
    int size()const;
    void printForward() const;    
    void printReverse() const;
    void printDebug() const;

    /**
    enables extra output for debugging purposes
    */
    static bool traceOn;

    private:
    /** head of list */
    Node* head;
    /** tail of list */
    Node* tail;
    /** count of number of nodes */
    int count;
};
#endif



//List.cpp                   I only included the parts of List.cpp that might be the issue
#include "List.h"
#include <iostream>
#include <iomanip>

using namespace std;


List::List()
{
 //List::size = NULL;
 head = NULL;
 tail = NULL;
}


List::~List()
{
 Node* current;
 while(head != NULL)
 {
  current = head-> next;
  delete current->previous;
  if (current->next!=NULL)
  {
   head = current;
  }
  else
  {
   delete current;
  }
 }
}

void List::add(int element)
{
 Node* newNode;
 Node* current;
 newNode->element = element;
 if(newNode->element > head->element)
 {
  current = head->next;
 }
 else
 {
  head->previous = newNode;
  newNode->next = head;
  newNode->previous = NULL;
  return;
 }

 while(newNode->element > current->element)
 {
  current = current->next;
 }

 if(newNode->element <= current->element)
 {
  newNode->previous = current->previous;
  newNode->next = current;
 }

}



//main.cpp
#include "List.h"
#include <iostream>
#include <string>

using namespace std;
//void add(int element);

int main (char** argv, int argc)
{    
 List* MyList = new List();
 bool quit = false;
 string value;
 int element;

 while(quit==false)
 {
  cin>>value;

  if(value == "add")
  {
   cin>>element;
   MyList->add(element);
  }
  if(value=="quit")
  {
   quit = true;
  }
 }
    return 0;
}

I'm doing everything I think I'm suppose to be doing. main.cpp isn't complete yet, just trying to get the add function to work first. Any help will be greatly appreciated.

Upvotes: 1

Views: 10069

Answers (4)

user2913837
user2913837

Reputation:

Your problem is not including all the different files in your command line arg compiler

Correct format:

get in correct directory

gcc -o list main.cpp List.cpp List.h

then you won't get anymore undefined references to functions

Good luck on building your 3 or 4 year old program...

Upvotes: 0

clstrfsck
clstrfsck

Reputation: 14847

Your command line should look something like g++ -o test.exe main.cpp List.cpp.

The key feature being to include both main.cpp and List.cpp.

There are other ways to do this, but this should get you started.

Upvotes: 1

GManNickG
GManNickG

Reputation: 504313

You're not compiling List.cpp. Add it to the command line.

In main.cpp, it's seeing (from List.h) "Hey, this class with this functionality will exist", but since you're not actually building/linking with List.cpp, it can't find the functions it's looking for.

Upvotes: 3

David Seiler
David Seiler

Reputation: 9725

Describe your build process. It looks as though you're not building List.cpp, or else not linking it with main.cpp.

Upvotes: 3

Related Questions