Re: Why some code for certain events declared to be static???

[Jared Davis <jared aiksaurus com>]

On Thursday 17 January 2002 07:13 pm, you wrote:
> GTK+ Tutorial has scribble.c code that has
> many subroutines that are tied to events.
>
> Many of these are static.  Please explain
> what static gives you in C.

Since C doesn't have namespaces like C++, static is a nice way of keeping 
your functions local to a particular file.  For example, if you try to write 
the following code in C:

[======== file "a.c" =========]

void foo() 
{
  /* do nothing */
}


[======== file "b.c" ==========]

void foo() 
{
   /* do nothing */
}

int main() 
{
   return 0;
}


Then you can compile these files individually just fine.  In other words:

	gcc -c a.c   (works fine)
	gcc -c b.c   (works fine)

But when you try to compile the resultant object code, you'll get a linker 
error:

	gcc a.o b.o 
	b.o: In function `foo':
	b.o(.text+0x0): multiple definition of `foo'
	a.o(.text+0x0): first defined here
	collect2: ld returned 1 exit status


This isn't good.  So, what you can do to avoid it is to simply define
your functions to be static so that they only exist within a particular 
file.  In other words, if we define foo() to be static in a.c, then it is 
local to a.c and it's name doesn't exist outside of a.c.  So, you won't
get any linker errors.  You could altenrately make the foo() in b.c static,
or even make them both static.

So basically it's just a way of presenting these name collisions when you
don't need to use the function outside of a single file.  

Cheers,
	Jared

-- 
Love all, serve all.