g++ fails on multiple files if there's a template involved...

[zeroth404]

but if I remove all the template stuff, it works. whats going on here?

list.cpp

#include "list.hh"

template <class type>
char List<type>::Get( void ) const {
  return 'a';
}

list.hh

template <class type>
class List {

public:
  char Get( void ) const;
};

try.cpp

#include <stdio.h>
#include "list.hh"

int main ( void ) {
  List<int> list;

  printf("%c\n", list.Get());
  
  return 0;
}

g++ list.cpp try.cpp

/tmp/cclUhOCm.o: In function `main':
try.cpp:(.text+0x11): undefined reference to `List<int>::Get() const'
collect2: ld returned 1 exit status

[srinathduraisamy]

For templates don't have a separe .cpp file.

Put your implementations inside the .h file itself, it will work.

Hope this helps.

[Rubberman]

Actually, you can implement a template instance as you did in list.cpp for List<int>::Get(void). However, you need to link it (list.o) specifically to make the executable since the List<int>::Get(void) method will not be automatically instantiated. In fact, every instantiated type of List will have to have its Get() method explicitly instantiated. Not a generally good use of templates, though legal.