Undefined reference error

[chunalt787]

I am trying to implement a queue based on a Linked List that I had to write previously. It is templated and for some reason I am getting the following error using g++ when I compile:

g++ LinkedQueueMain.cpp -o LinkedQueueMain
/tmp/ccqwStpK.o: In function `main':
LinkedQueueMain.cpp:(.text+0x2ee): undefined reference to `LinkedQueue<char>::operator=(LinkedQueue<char> const&)'
collect2: ld returned 1 exit status

It is saying undefined reference however I have declared and defined it so I cant figure out what the problem is.

This is my class declaration and definition: // LinkedQueue.h

#ifndef LINKEDQUEUE_H
#define LINKEDQUEUE_H

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

template<typename T> class LinkedQueue;

template<typename T>
std::ostream& operator<<(std::ostream& out, const LinkedQueue<T>& queue);

template<typename T>
class LinkedQueue {
private:
LinkedList<T> ll;

public:
// user-defined exceptions
class QueueEmptyException : public RuntimeException {
public:
QueueEmptyException() : RuntimeException("Access to an empty queue") {}
};

LinkedQueue() { } // constructor
~LinkedQueue() { } // destructor
LinkedQueue(const LinkedQueue& queue) { ll = queue.ll; } // copy constructor
LinkedQueue& operator=(const LinkedQueue& queue); // assignment operator

// I have cut out accessory function declarations

friend std::ostream& operator<< <>(std::ostream& out, const LinkedQueue<T>& queue); // overload <<
};

//-------------------------------------------------------------------------------------------------------------------------

template<typename T>
LinkedQueue<T>& LinkedQueue<T>::operator=(const LinkedQueue& queue) {
ll = queue.ll;
return *this;
}

// other functions defined here I just cut them out for space

#endif

Here is my main: #include "LinkedQueue.h"
#include <iostream>
#include <string>
#include <iterator>
using namespace std;

int main()
{
LinkedQueue<char> queue;
LinkedQueue<char> queue_copy;

//===== enqueue() =====

queue.enqueue('1');
queue.enqueue('2');
queue.enqueue('3');
queue.enqueue('4');
queue.enqueue('5');
queue.enqueue('6');

queue_copy = queue; //THIS IS WHERE I BELIEVE THE PROBLEM IS
cerr << "assigning queue to queue_copy, queue_copy = ";
cerr << queue_copy << endl;
cerr << "size of queue_copy = " << queue_copy.size() << endl;
cerr << "first of queue_copy = " << queue_copy.first() << endl << endl;

return 0;
}

Thanks in advance for any help.

[Sky Diploma]

I am not sure about this , But Why returning (*this)? In your = operator.

[Sci@phy]

Are you sure this code works:

ll = queue.ll;

'll' is under private section, right? I'm not sure if you can access it.
Here's my code example if it helps:

//operators
//=
Complex& Complex::operator=(Complex const& aCplx){
    if (this != &aCplx){
        mNum.Im = aCplx.getIm();
        mNum.Re = aCplx.getRe();
    }
    return *this;
}

[Sci@phy]

I am not sure about this , But Why returning (*this)? In your = operator.

(*this) is returned so you can write things like:
myObjA = myObjB = myObjC;

[chunalt787]

Our professor gave us a skeleton of the code and it already had the return statement in it so I didn't change it. The LinkedList = operator overload returns a pointer as well.

[chunalt787]

Are you sure this code works:

ll = queue.ll;

'll' is under private section, right? I'm not sure if you can access it. Here's my code example if it helps:

//operators
//=
Complex& Complex::operator=(Complex const& aCplx){
    if (this != &aCplx){
        mNum.Im = aCplx.getIm();
        mNum.Re = aCplx.getRe();
    }
    return *this;
}

Well the definition is within the class and classes can access their own private data members so ya it should work. I tried putting it in the public section just to check and it did the same thing. As to your example thats basically the same thing that im trying to do. I don't see why mine doesnt work.

[Sci@phy]

Well the definition is within the class and classes can access their own private data members so ya it should work. I tried putting it in the public section just to check and it did the same thing. As to your example thats basically the same thing that im trying to do. I don't see why mine doesnt work.

I'm not sure about this.
Function can access IT'S own members (this->memb1; this->memb2;)
But I'm really not sure about accessing other instance of same type...

Maybe your problem is in something else...

[chunalt787]

I'm not sure about this. Function can access IT'S own members (this->memb1; this->memb2;) But I'm really not sure about accessing other instance of same type...

Maybe your problem is in something else...

I have done something very similar to that previously so I am pretty sure thats not the problem.

BTW Thanks to everyone thats been trying to help. This is getting really frustrating.

[Sci@phy]

Zip and post entire code, please.
It's frustrating me now too :)

[chunalt787]

I think its zipped now thats the first time I have done that. I am sorry its been so long. I had an emergency that kept me from the computer for a couple days. Im back now and still annoyed by this error.

[Narue]

template<typename T>
LinkedQueue& LinkedQueue::operator=(const LinkedQueue& queue)
{
	ll = queue.ll;
	return *this;
}

You need to be more careful about specifying template parameters:

template<typename T>
LinkedQueue<T>& LinkedQueue<T>::operator=(const LinkedQueue<T>& queue)
{
	ll = queue.ll;
	return *this;
}

[chunalt787]

o crap i must have zipped an older version. I had had that and it still didn't work. I just ended up redoing the entire header and now it works so thank you to everyone who helped