Re: Where to include header files - relates to last question on variable scope

FROM : Chris Hanson
DATE : Sun Oct 31 20:10:06 2004

On Oct 31, 2004, at 7:10 AM, Ole Voss wrote:
> This also means, that I have to include the header file wherever I
> need it?
> That could mean that the same class has to be recompiled tens of times
> -
> right?


You need to distinguish between the declaration and the definition.

The definition needs to be compiled only once.  The declaration needs
to appear prior to its use in any compilation unit that needs to make
use of the information in it; that's what #include and #import do.

This is true for all of C, C++, and Objective-C and is fundamental to
these languages' compilation model.

> So what possibilities do I have to create global variables?


You create global variables in Objective-C in exactly same way that you
create them in C.  Declare your global variable in a header file as
extern, and define it in a single implementation file.

  -- Chris