Help with "Undefined Reference" Error

[Ehorn]

Hello all;

Working on a project program for my programming class and I am having a hell of a time with it. I am pretty sure the solution to this problem is simple and staring me in the face, so please feel free to laugh at me after the error is pointed out :).

After trying to compile (using either Codeblocks or Bloodshed) the code shown below, I get an "driver_dictionary.cpp: undefined reference to `Dictionary::Dictionary()' error.

Here are the files that I am using:

driver_dictionary.cpp (I CAN NOT modify this file according to project rules):

#include <cassert>
#include <iostream>
#include <string>

#include "Dictionary.h"

using namespace std;

void test1()
{
Dictionary one; <-- Undefined error on this line
one.add ("ape");
one.add ("zipper");

assert( one.contains ("caT"));
assert( !one.contains ("dog"));
}

void test2()
{
Dictionary two; <-- undefined error on this line
string word ;
cout << "input words to add to the dictionary;enter ??? to stop ";
cin >> word ;
while ( word != "???" )
{
two.add (word);
cin >> word;
}
cout << "input word to search for in dictionary;enter ??? to stop ";
cin >> word ;
while ( word != "???" )
{
cout << two.contains (word) << endl;
cin >> word;
}

}
int main(int argc, char** argv)
{
test1();
test2();


return 0;
}

dictionary.h (I CAN NOT modify this file according to project rules):

#ifndef DICTIONARY_H
#define DICTIONARY_H

#include <string>

class Dictionary
{
public:
Dictionary();
void add (std::string word);
bool contains (std::string word) const;

private:

struct LinkedListNode
{
std::string data;
LinkedListNode* next;
};

LinkedListNode* first;
};
#endif

and finally the ONLY file that I can modify:

dictionary.cpp: (This file will be modified to perform the required actions on a linked list (add and contain functions) AFTER I figure out why I am getting the undefined error:)

#include <iostream>
#include <string>
#include <cstdlib>

#include "dictionary.h"

using namespace std;

string toLowerCase (string word)
{
string result = word;
for (int i = 0; i < word.length(); ++i)
if (word[i] >= 'A' && word[i] <= 'Z')
result[i] = result[i] + 'a' - 'A';
return result;
}
// modify this function to add a word to the dictionary in alpha order
void Dictionary::add (std::string word)
{
cout << word;
}
// check to see is the word already exists before adding the word
bool Dictionary::contains (std::string word) const
{
int k = 1;
cout << k;
return k >= 0;
}

Any assistance would be greatly appreciated and thank you very much for your time!

Eric

[hamsterman]

In dictionary.h a constructor is declared, however it has no definition. Add Dictionary::Dictionary() {/*you might want to do some initializing*/} in whatever cpp file you can.

[Ehorn]

Can you please elaborate on where to add Dictionary::Dictionary()?

From my understanding, when the constructor was called in the .h file, a STRUCT was created using the information in the "private" section. Is this correct or am I way off base?

Or do I need to add something like this to the dictionary.cpp file to set up the linked list?

Dictionary::Dictionary ()
{
string data;
Node *next;
Node *first;
}

[hamsterman]

Constructor is a function and a function needs an implementation. Put it where you put all of your implementations - in dictionary.cpp

From my understanding, when the constructor was called in the .h file, a STRUCT was created using the information in the "private" section. Is this correct or am I way off base?

I don't get what you're asking..

Or do I need to add something like this to the dictionary.cpp file to set up the linked list?

In a constructor you don't declare members. You (may) give them initial values. For example it is good to initialize your pointers to 0.

see http://www.cplusplus.com/doc/tutorial/classes/ (scroll down to "Constructors and destructors" )

[Ehorn]

Thanks Hamsterman for the help.
Adding the constructor to the implementation file work great to get me started. However I am having trouble initializing the head pointer to NULL. Added a new post with the current code.

I think I am beginning to HATE linked lists :(