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From: tada@athena.mit.edu (Michael J Zehr)
Newsgroups: comp.std.c
Subject: Re: legality of assignment of function to a void *.
Summary: K&R2 misleadiing
Message-ID: <1990Nov14.031125.14027@athena.mit.edu>
Date: 14 Nov 90 03:11:25 GMT
References: <1990Nov12.211511.2344@batcomputer.tn.cornell.edu> <1990Nov13.174920.2235@zoo.toronto.edu>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: Massachusetts Institute of Technology
Lines: 25

In article <1990Nov13.174920.2235@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes:
>In article <1990Nov12.211511.2344@batcomputer.tn.cornell.edu> lijewski@theory.tn.cornell.edu (Mike Lijewski) writes:
>>double f(double x) { return x * x; }
>>   void *ptr = f;
>
>Function pointers are a whole different universe from normal pointers, in
>principle.

I've tried to follow the new ansi rules pretty carefully and I wasn't
aware of this until recently when it was pointed out here(*).  My main
source of confusion was K&R2 (p. 199, "Any pointer may be converted to
type void * without loss of information.  If the result is converted
back to the original pointer type, the original pointer is recovered.")

This seems very misleading to me.  (Yes, I know that K&R2 is not the
official ANSI specification for C.)  Does anyone know if this was
something that was changed after K&R2 was written?  What about other
statements in K&R2 that are misleading or conflict with the standard?

-michael j zehr

(*) And fortunately or unfortunately, depending on how you look at it, I
do most of my work on a VAX, where a pointer is a pointer is a pointer,
so I never had problems with any code I wrote, nor did the compiler ever
complain.