Incompatible warning using 'exit' - huh?

I'm using i686-apple-darwin8-gcc-4.0.1 to compile the following code:

#include <unistd.h>
#include <stdio.h>

int main()
{
if((write(1, "Here is some data\n", 1) != 1
write(2, "A write error has occured on file descriptor 1\n", 46);

exit(0);

}

Compiling with:

gcc -o simple_write simple_write.c

Getting:

simple_write.c: In function 'main':
simple_write.c:10: warning: incompatible implicit declaration of
built-in function 'exit'

-Cheers

I got the answer from the folks over at comp.sys.mac.programmer.help.
Simply replace the unistd.h header with stdlib.h -- and that should do
it.

-Cheers

wrote:
> I'm using i686-apple-darwin8-gcc-4.0.1 to compile the following code:
>
> #include <unistd.h>
> #include <stdio.h>
>
> int main()
> {
> if((write(1, "Here is some data\n", 1) != 1
> write(2, "A write error has occured on file descriptor 1\n", 46);
>
> exit(0);
>
> }
>
> Compiling with:
>
> gcc -o simple_write simple_write.c
>
> Getting:
>
> simple_write.c: In function 'main':
> simple_write.c:10: warning: incompatible implicit declaration of
> built-in function 'exit'
>
> -Cheers