Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!auspex!guy
From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.lang.c
Subject: Re: C++ and ANSI C
Message-ID: <1567@auspex.auspex.com>
Date: 5 May 89 19:25:57 GMT
References: <12005@paris.ics.uci.edu> <44100029@hcx2> <1989May4.001911.3382@utzoo.uucp> <3934@tekcrl.LABS.TEK.COM>
Reply-To: guy@auspex.auspex.com (Guy Harris)
Organization: Auspex Systems, Santa Clara
Lines: 33

>> 1. "extern foo();" means (so to speak) "extern foo(...);" in ANSI C and
>> 	"extern foo(void);" in C++
>
>    Number 1 is incorrect since C++ uses '...' to indicate that the number
>and type of arguments is unknown.  The void keyword in ANSI C indicates
>that the function takes no arguments.  No arguments in the prototype in
>C++ means that there are no arguments.

Uhh, that's what he *said*.  ANSI C *also* uses "..." to indicate that
the number and type of arguments (following a certain argument) is
unknown.  The "following a certain argument" is relevant - the December
7, 1988 draft indicates that the ellipsis must follow a comma, which
follows an argument; this may be what the "so to speak" indicates.  "The
empty list in a function declarator that is not part of a function
definition specifies that no information about the number or types of
the parameters is supplied," so "extern foo();" is equivalent to what
"extern foo (...);" would mean if it were allowed.

"No arguments in the prototype in C++ means that there are no arguments"
is equivalent to "'extern foo();; means ... 'extern foo (void);' in
C++"; according to my copy of S ("S" being a construct whose meaning is
determined by analogy to "K&R" :-)), under "15.3 Anachronisms", "The
keyword 'void' may be used to indicate that a function takes no
arguments, thus '(void)' is equivalent to '()'" (so to speak;
presumably,

	() fprintf(stderr, "Doom, defeat, and despair!\n");

is not equivalent to

	(void) fprintf(stderr, "Doom, defeat, and despair!\n");

:-)).