Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: on the fringe of C syntax/semantics
Message-ID: <11216@smoke.BRL.MIL>
Date: 4 Oct 89 20:51:09 GMT
References: <80100001@bonzo>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 19

In article <80100001@bonzo> roy@bonzo.sts.COM writes:
>When calling the va_arg() function, the 2nd parameter is supposed to be
>simply a type, such as int, char, char *, etc.  So, the first question
>is, how does it know what type you specified?

It doesn't work with all types, only those for which appending "*"
produces a type that is a valid pointer to the argument type.  Of
course the va_arg() MACRO (not function) does this by straightforward
macro expansion of the argument using a template where the expanded
argument is followed by a "*".

Sometimes you need to provide a typedef name, if the type is complex
enough.

>'(int *())' and '(int ())' were two tries at declaring a general function
>that returns an 'int', but they didn't work.

int (*)() is a valid type for a pointer to function (with unspecified
argument information) returning an int value.