NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/comp/os/vms/21852

Internet Message Format | 1993-01-24 | 2.3 KB

Path: sparky!uunet!usc!elroy.jpl.nasa.gov!nntp-server.caltech.edu!SOL1.GPS.CALTECH.EDU!CARL
From: [e-mail] (Carl J Lydick)
Newsgroups: comp.os.vms
Subject: Re: functions as arguments in DEC C
Date: 23 Jan 1993 22:39:34 GMT
Organization: HST Wide Field/Planetary Camera
Lines: 42
Distribution: world
Message-ID: <[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail]
NNTP-Posting-Host: sol1.gps.caltech.edu

In article <[e-mail]>, [e-mail] (Burkhard Burow) writes:
=My application generates 'wrapper' routines which pass along functions to
=other routines. The wrapper routines do not know the type of the functions they
=are passing along.
=
=Simplified e.g.
=
=void q ( int (*c)() );     /* A. prototype of q                              */
=
=void __q( void ( *a)() )   /* B. function with a function as argument        */
={
=q( a );                    /* C. pass the function parameter on to q.        */
=}
=
=For which the C compiler complains:
=
=q( a );
=^
=%CC-E-PASNOTREFCOM, In this statement, the referenced type of the pointer value
="a" is "Function (...) returning void", which is not compatible with "Function (
=...) returning signed int".
=at line number 5
=
=
=Silicon Graphics 2.0.1 ANSI generates a similar warning, but can be satisfied
=by casting 'a' in line B. as follows:
=
=q( *(void **)&a );

Well, if you want to cast a as a signed int (which is what the error message
told you, and your declaration implies, the function q requires as an argument),
you don't use "*(void **) &a", you use "*(int **) &a".  Have you tried that?
Note:  Since I don't have DEC C, this is just a guess, based on what you've
told us, and the fact that VAX C accepts the syntax I've suggested.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: [e-mail] | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.