getopt with gcc -ansi

[Susukita Ryutaro]

> Read the FAQ:
> 3.11.	I get some errors with `gcc -ansi'. Isn't glibc ANSI compatible?

I have read this FAQ. The answer says glib is ANSI compatible if you
use only the header files and the library functions defined in ANSI.
But the FAQ is a little different from my question. <unistd.h> is not
defined in ANSI. For example, the declaration of sleep in <unistd.h>
seems effective even with -ansi. What is the difference between getopt
and sleep?

susukita