Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!texbell!merch!sneaky!gordon
From: gordon@sneaky.UUCP (Gordon Burditt)
Newsgroups: comp.lang.c
Subject: Re: Passing functions in C
Message-ID: <29381@sneaky.UUCP>
Date: 15 Mar 90 06:40:14 GMT
References: <1990Mar9.045151.9601@ucselx.sdsu.edu> <3242@hcx1.SSD.CSD.HARRIS.COM>
Distribution: usa
Organization: Gordon Burditt
Lines: 49

>>i would like to be able to write a procedure that takes as
>>a parameter a procedure name and then using that name
>>calls the procedure.
>>
>>ie  runAProcedure(myProcedure)
>>   {
>>	myProcedure
>>}
>>
>>Is this possible to do in C?  Any help or advise is appreciated
>>tho please e-mail responses so the net won't be cluttered.
>
>NO! It is not possible to do in C! (Im pretty sure you cant do this
>in ANSI C either). 

Yes, it is.  Some really old compilers did accept myfunct(), where
myfunct is of type pointer-to-function-returning-something, as meaning
the same as (*myfunct)().  Modern compilers tend to at least give
warnings about it.

From section 3.7.1 of the Jan 1988 ANSI C draft (sorry, that's the most
recent one I have):
QUOTE

To pass one function to another, one might say
	int f(void)
	/* ... */
	g(f);

Note that f must be declared explicitly in the calling function, as
its appearance in the expression g(f) was not followed by (.
Then the definition of g might read

	g(int (*funcp)(void))
	{
		/* ... */ (*funcp)() /* or funcp() ... */
	}
or, equivalently,
	g(int func(void))
	{
	/* ... */ func() /* or (*func)() ... */
	}

END QUOTE.

ANSI allows this, and even gives an example of it.

						Gordon L. Burditt
						sneaky.lonestar.org!gordon