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Path: utzoo!linus!decvax!genrad!mit-eddie!mp
From: mp@mit-eddie.UUCP (Mark Plotnick)
Newsgroups: net.lang.c
Subject: ptrs to functions
Message-ID: <628@mit-eddie.UUCP>
Date: Sun, 21-Aug-83 18:26:49 EDT
Article-I.D.: mit-eddi.628
Posted: Sun Aug 21 18:26:49 1983
Date-Received: Mon, 22-Aug-83 01:25:17 EDT
Organization: MIT, Cambridge, MA
Lines: 20

This addresses-of-arrays business made me wonder what happens
when you try to pass functions as parameters.  Now, all you
people who grew up with the V7 C compiler know that, in order
to pass a function as a parameter, all you need do is mention
the function's name in the actual parameter list.  The declaration
of the formal would look something like "int (*func)();", and to
invoke it you'd do something like "j = (*func)(i)".

With 4.1bsd pcc, the rules are a bit lax.  You can declare a
formal as "int func();" and only get a mild warning.  You can
even do "j = func(i)" and get no warning at all.  In both cases,
func is really a pointer to the function.

I'm not going to take a stand as to whether or not the pcc rules
violate the definition of C; after all, the most recent C
reference manual is from 1979 or so, and who knows what's
changed since then.  But pcc's extensions make the job of
porting code to V7 a pain, sometimes.

	Mark (genrad!mit-eddie!mp, eagle!mit-vax!mp)