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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: weird c code/ c test
Message-ID: <6287@brl-smoke.ARPA>
Date: Sat, 15-Aug-87 12:33:15 EDT
Article-I.D.: brl-smok.6287
Posted: Sat Aug 15 12:33:15 1987
Date-Received: Tue, 18-Aug-87 03:19:24 EDT
References: <1089@gilsys.UUCP> <175400004@uxc.cso.uiuc.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 20

In article <175400004@uxc.cso.uiuc.edu> hamilton@uxc.cso.uiuc.edu writes:
>next, you'll want me to #include <time.h> when i use ctime().

Yes, as a matter of fact.

Both X3.159-198x and IEEE 1003.1 permit the application code to omit
the header that is supposed to declare the type of a library function
if and only if the application code itself correctly declares the
type; this is not always possible without some definitions from the
header.  In the case of printf(), IF you can correctly declare its
type without <stdio.h>, then having done so you could omit <stdio.h>.
However, if there happened to be a spiffy macro implementation of the
function defined in <stdio.h>, you would be missing out on it thereby,
so it is not generally advisable to circumvent the declarations from
the standard headers.  The other problem is, printf() is a variable-
arguments function, and as such will require a correct function
prototype to be in scope in an ANSI C environment.  Although one
could declare the type "by hand" using #if __STDC__ to accommodate
the differences between old C and ANSI C, it is much simpler and more
convenient to let <stdio.h> take care of getting the declaration right.