Templates, Classes and unresolved symbols

[mteichta]

Dear All,

I have the following

I have created a templated class defined as

template <class T> class Queue
{
public:
Queue();
~Queue();
Display();
};


this sits in templclasses.h

and the following in templclasses.cpp

#include &quot;stdafx.h&quot;
#include &quot;templclasses.h&quot;
#include <iostream>

template <class T> Queue<T>::Queue()
{}
template <class T> Queue<T>::~Queue()
{}
template <class T> Queue<T>:isplay()
{}

I instansiate via

typedef Queue<data> Queue;
Queue Now;

when i try to link i get the following error
emplatesDlg.obj : error LNK2001: unresolved external symbol &quot;public: __thiscall Queue<struct data>::~Queue<struct data>(void)&quot; (??1?$Queue@Udata@@@@QAE@XZ)
templatesDlg.obj : error LNK2001: unresolved external symbol &quot;public: __thiscall Queue<struct data>::Queue<struct data>(void)&quot; (??0?$Queue@Udata@@@@QAE@XZ)

can anyone please assist ?

 

[SeekerOfKnowledge]

Put the implementation of the template method in the cpp
file, either after the class definition or inside it.
This should solve the problem

 

[mteichta]

i have now moved all into the one header...i now have another problem

i have

template <class T> class Queue
{
public:
Queue() ;
~Queue() ;
void Display(int value);
};
template <class T> Queue<T>::Queue()
{
}
template <class T> Queue<T>::~Queue()
{
}
template <class T> void Queue<T>:isplay(int value)
{
}

I instansiate with

typedef Queue<int> TItems;
TItems test;

when i call

test.Display(1);

i get

'Display' : function does not take 1 parameters

any help would be great

 

[SeekerOfKnowledge]

I do not know exactly what the reason might be for this bug, but try to do the following : Put the implementation inside the class definition:
template <class T> class Queue
{
public:
Queue() {};
~Queue() {};
void Display(int value){};
};

This might help.. Try to lose the typedef, it might cause problems, too
======
SeekerOfKnowledge
======

 

[mteichta]

Ok..

i now have

template <class T> class Queue
{
public:
Queue() ;
~Queue() ;
void Display(int value){};
};

Queue<int> TItems;
int test=1;
TItems.Display(test);

SAME ERROR !!!

 

[dayan]

#include &quot;templclasses.h&quot;


template <class T> Queue<T>::Queue()
{}
template <class T> Queue<T>::~Queue()
{}
template <class T> void Queue<T>:isplay(T &val)
{
fprintf(stderr,&quot;%d&quot;,val);
}
void main()
{
typedef Queue<int> Help;
Help test;
int val = 3;
test.Display(val);
}

This should solve your problem

 

[mteichta]

hi

thanks for the input but this didnt solve the problem.

i implemented what you suggested and I recieved the same error.

the example you give shows how to pass a generic value, i need to pass both generic and specific parameters. For example

test.Display(data,1);

but i cant get the template to understand *ANY* parameters