From: kaz AT cafe DOT net (Kaz Kylheku)
Newsgroups: comp.lang.c,comp.os.msdos.djgpp
Subject: Re: Casting void pointers
Organization: Internet Direct
Lines: 22
Sender: bill AT espresso DOT cafe DOT net
Message-ID: <6mkfnv$hcr@espresso.cafe.net>
References: <6mkaos$k7o AT dfw-ixnews6 DOT ix DOT netcom DOT com>
Reply-To: kaz AT cafe DOT net
Date: Mon, 22 Jun 1998 02:38:15 GMT
NNTP-Posting-Host: 204.244.119.1
NNTP-Posting-Date: Sun, 21 Jun 1998 19:38:15 PDT
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

In article <6mkaos$k7o AT dfw-ixnews6 DOT ix DOT netcom DOT com>,
Todd Rowan <rowan3 AT ix DOT netcom DOT com_nospam> wrote:
>How do you explicity cast a void pointer to a function pointer? Or do you

You can create a typedef name for the function pointer and then use
the parenthesized typedef name. Or you can write cast expressions
like:

	void *q = 0;
	double (*p)(double, int) = (double (*)(double, int)) q;

Note that conversion between pointers to void and function pointers
is not a feature of the C language; it is merely a common extension.

In standard C, pointers to functions and pointers to object/incomplete types
are incommensurable.

>even need to cast void pointers manually?

Yes; pointers to void may only be implicitly converted to object pointers
or pointers to incomplete type. Converting a function point to void *
and vice versa requires a cast operator.