Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!att!chinet!john
From: john@chinet.chi.il.us (John Mundt)
Newsgroups: comp.lang.c
Subject: Re: pointers to functions
Message-ID: <9429@chinet.chi.il.us>
Date: 31 Aug 89 13:47:42 GMT
References: <1679@hydra.gatech.EDU>
Reply-To: john@chinet.chi.il.us (John Mundt)
Organization: Chinet - Public Access Unix
Lines: 28

In article <1679@hydra.gatech.EDU> wj4@prism.gatech.EDU (JOYE,WILLIAM A) writes:
>Ok, C gurus of the world... is the following code portable and why or why
>not? 
>
>	void (*f)() = printf;
>	f("Hello, world\n");		/* are these two methods equivalent? */
>	(*f)("Hello, world again\n" );

They are.

I noticed the same thing on AT&T 3b2/400's and 3b1's.  The assembly code
generated for either form is exactly the same.  The compiler is not the
latest release.  (I'd made a typo once and expected the program to fail.
It didn't.)

In effect, this means that for pointers to functions, the pointer
is not dereferenced, thus in effect f == *f.

K & R are quite definite in stating the correct form is (*f)(), but
apparently even the gods can lie.

If f holds the address of the start of the function, *f really doesn't
have any meaning.  
-- 
---------------------
John Mundt   Teachers' Aide, Inc.  P.O. Box 1666  Highland Park, IL
john@chinet.chi.il.us
(312) 998-5007 (Day voice) || -432-8860 (Answer Mach) && -432-5386 Modem