Question

Possible Duplicate:
Why can templates only be implemented in the header file?
Why should the implementation and the declaration of a template class be in the same header file?

I’m a computer science student at some university and we were given files to work on for hw.
And I wasn’t sure how this kind of instantiation worked.

long code short it looked something like this.

in List.h

#ifndef _LIST_H_
#define _LIST_H_

#include <iterator>
#include <ostream>

template <class T>
class List

/* implementation below but not relevant to this post */
.
.
.
.

….the last few lines of the file below.

#include "list.cpp"

#include "list_given.cpp"

#endif

and List.cpp didn’t include List.h

I don’t understand how including List.cpp in the header file works.

Answer 1

#include just causes textual substitution, nothing else, so it’s as if the entire contents of list.cpp were duplicated in the header file. This has nothing to do with “explicit template instantiation”.

list.cpp doesn’t include the header because otherwise the header would include itself recursively.