InsertNode function shutting down program

Question

I am having trouble coding a Linked List Template. It compiles but I get these errors:

1>main.obj : error LNK2019: unresolved external symbol "public: __thiscall LinkedList::~LinkedList(void)" (??1?$LinkedList@H@@QAE@XZ) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: void __thiscall LinkedList::deleteNode(int)" (?deleteNode@?$LinkedList@H@@QAEXH@Z) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: void __thiscall LinkedList::displayList(void)" (?displayList@?$LinkedList@H@@QAEXXZ) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: void __thiscall LinkedList::insertNode(int)" (?insertNode@?$LinkedList@H@@QAEXH@Z) referenced in function _main

1>c:\users\pr0hz\documents\visual studio 2010\Projects\ListTemplate\Debug\ListTemplate.exe : fatal error LNK1120: 4 unresolved externals

Any help would be greatly appreciate as I have been staring at my screen for the past couple of hours trying to solve this problem. Here is my code:

main.cpp

#include <iostream>
#include <conio.h>
#include "LinkedList.h"

using namespace std;


int main()
{   
LinkedList<int> list;

list.insertNode(5);
list.insertNode(7);
list.insertNode(1);
list.insertNode(19);
list.insertNode(16);
list.insertNode(22);

cout << "\nDisplay the list: \n";
list.displayList();
cout << endl;

list.deleteNode(16);

cout << "\nDisplay node with 16 deleted: \n";
list.displayList();
cout << endl;

LinkedList<int> list2 = list;

cout << "\nDisplay List 2: \n";
list2.displayList();
cout << endl;
getch();

return 0;
}

LinkedList.h

#ifndef LINKEDLIST_H
#define LINKEDLIST_H
#include <iostream>

using namespace std;

template <class T>
class LinkedList
{
private:
struct ListTemplate
{
    T value;
    ListTemplate *next;
};

ListTemplate *head;


public:
//Constructor
LinkedList()
{ head = NULL; }

//Destructor
~LinkedList();

//Copy Constructor
LinkedList(ListTemplate &obj)
{
    ListTemplate *nodePtr = &obj;   //Move through the list
    ListTemplate *newNode = new ListTemplate;

    if(!head)
        return;
    else
    {
        newNode = head;

        while(nodePtr->next)
        {
            nodePtr = nodePtr->next;
            newNode->next = nodePtr;
        }

    }
}

void appendNode(T);
void insertNode(T);
void deleteNode(T);
void displayList();
};
#endif

LinkedList.cpp

#include "LinkedList.h"
#include <iostream>

using namespace std;

template <class T>
void LinkedList<T>::appendNode(T newValue)
{
ListTemplate *newNode;  //Point to the new node
ListTemplate *nodePtr;  //Move through the list

//Allocate new node and store num there
newNode = new ListTemplate;
newNode->value = num;
newNode->next - NULL;

if(!head)
    head = newNode;
else
{
    //Initialize the nodePtr as head to move through the list
    nodePtr = head;

    //While there is still a node, we move through it until there is no more
    while (nodePtr->next)
        nodePtr = nodePtr->next;

    //Append the node
    nodePtr->next = newNode;
}
}

template <class T>
void LinkedList<T>::insertNode(T newValue)
{
ListTemplate *newNode;              //New Node
ListTemplate *nodePtr;              //Move through the list
ListTemplate *previousNode = NULL;  //The previous node

//Allocate new node and store num
newNode = new ListTemplate;
newNode->value = num;

//If no node, new node is head
if (!head)
{
    head = newNode;
    newNode->next = NULL;
}

else //Insert node where it needs to be
{
    nodePtr = head;         //Beginning position

    previousNode = NULL;

    //Skip nodes that are less than newNode
    while(nodePtr != NULL && nodePtr->value < num)
    {
        previousNode = nodePtr;
        nodePtr = nodePtr->next;
    }

    //If newNode is the 1st in the list, insert it in slot 1
    if (previousNode == NULL)
    {
        head = newNode;
        newNode->next = nodePtr;
    }
    else //Insert after previous node
    {
        previousNode->next = newNode;
        newNode->next = nodePtr;
    }
}
}

template <class T>
void LinkedList<T>::deleteNode(T searchNum)
{
ListTemplate *nodePtr;
ListTemplate *previousNode;

//If the list is empty, do nothing
if(!head)
    return;

//See if the first node is the one
if(head->value == num)
{
    nodePtr = head->next;
    delete head;
    head = nodePtr;
}

else //Find the node to delete
{
    nodePtr = head;

    //Skip the nodes not equal to num
    while (nodePtr != NULL && nodePtr->value != num)
    {
        previousNode = nodePtr;
        nodePtr = nodePtr->next;
    }

    //Delete node and link previous node to the one of the one being deleted
    if (nodePtr)
    {
        previousNode->next = nodePtr->next;
        delete nodePtr;
    }
}
}

template <class T>
LinkedList<T>::~LinkedList()
{
ListTemplate *nodePtr;
ListTemplate *nextNode;

nodePtr = head;

while (nodePtr != NULL)
{
    nextNode = nodePtr->next;

    delete nodePtr;

    nodePtr = nextNode;
}
}

template <class T>
void LinkedList<T>::displayList()
{
ListTemplate *nodePtr;

nodePtr = head;

while(nodePtr)
{
    cout << nodePtr->value << " ";
    nodePtr = nodePtr->next;
}
}

Once again, thanks for your help!

Thanks! I did that and it totally worked. Well, after toying with it for just a little bit, but seriously, thank you! — user3314596

Leeor Leeor · Accepted Answer · 2014-04-12T19:23:35

You shouldn't be implementing template functions in source files.
See here - Why can templates only be implemented in the header file?

Try moving all the template functions into the header file (LinkedList.h), and recompile

InsertNode function shutting down program

2 Answers