Templates declarations in header files?

Is it legal to have only a template declaration in a header file if the template is defined somewhere in a regular file?  That is,

For example, can I just include the header file "SomeClass.h" into the "SomeProgram.cpp" as long as the file "SomeClass.cpp" is compiled and linked into the program (but not included into "SomeProgram.cpp").  

template <class T> class SomeClass
   int x;
   SomeClass(int i);  // Declared, not defined.
// Define constructor.
template <class T> SomeClass::SomeClass(int i);
  x = i;
#include "someclass.h"
  SomeClass SC(5);

A EE client was trying to do this in a program and I didn't think it was allowed,  I just want to make sure.  It caused linker errors, which seems to make sense as things compiled, but the necessary functions weren't there.
LVL 22
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Actually template class public functions must be declared inline.
Yes, this is allowed according to the new C++ standard. It is called "separate template compilation". However, only a few compiler support it, and the ones I use are not among them :-(

See http://www.ses.com/~clarke/cpptips/templ_sep_comp_spec for a short explanation.
nietodAuthor Commented:
Sorry Galkin, but it looks like you are out of date.

Yonat, If you answer the question I'll give you the points.
CompTIA Security+

Learn the essential functions of CompTIA Security+, which establishes the core knowledge required of any cybersecurity role and leads professionals into intermediate-level cybersecurity jobs.

I am not sure but I think that you have to use the extern keyword on the function bodies when they are not inline.
Danny Pav
nietodAuthor Commented:
Yes, that is correct.  Check the web site that yonat posted for details.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Gosh .. this C++ language thingy sure does get changed more than a baby on laxatives !!

It certainly keeps us poor experts on our toes .. and keeps those not-so-poor people that write compilers in jobs for a long time.

It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.