hey
according to me the program crashing should be a different reason as i have included a cpp file in programs and run them without error.. post the problematic code..

Hello,
Let's not refer to ourselve but to compiler!
Try this:
__________________________
File 1: Main.cpp
__________________________
#include <stdio.h>
#include "ADD2.h"

int main (int argc, char * const argv[]) {
int a=3;
float b=3.3;
printf("\na=%d \t ADD2(a)=%d",a,ADD2(a));
printf("\nb=%f \t ADD2(b)=%f",b,ADD2(b));
}
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File 2: ADD2.h
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#ifndef ADD2_H
#define ADD2_H
template <class T>
T ADD2(T a);

template <class T>
T ADD2(T a)
{
a=a+(T)2;
}
#endif
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This just works fine but if you remove function body then like this:
Modified File 2: ADD2.h
__________________________
#ifndef ADD2_H
#define ADD2_H
template <class T>
T ADD2(T a);
#endif
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ADDED File 3: ADD2.cpp
__________________________
#include "ADD2.H"
template <class T>
T ADD2(T a)
{
a=a+(T)2;
}
__________________________
This Time again it will be compiled but a run time error like this can happen:
ZeroLink: unknown symbol '__Z4ADD2IiET_S0_'

It seems clear that we must define all the template in *.hpp??

What's your compile command line?

I use gcc 3.3++ on MAC or Xcode. But from concept of template it could be clear that it must be implemented in *.h, so on linking time required instances can be made?

Am I right?
:rolleyes:

Put the implementation in an .hpp file and have it include the .h.

Then, in your main program file, include the .hpp file rather than the .h
Also, I think you want a reference in your ADD2 function (T & a), otherwise, I don't think 'a' will change... Also, you don't return anything in your function, you're supposed to return a T.

Thanks,

This was just a test file.

BTW, putting the implementation in an *.hpp file is still in header file. I am not receiving my answer, how refering from an *.hpp file to *.h file can help me?

Thanks,Reza