Message-Id: <199604051627.LAA11738@mail-e2b-service.gnn.com>
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Date: Fri, 05 Apr 1996 11:30:44
From: Jethro Wright <Jetman AT gnn DOT com>
To: djgpp AT delorie DOT com
Subject: A Proper Cast for a Funtion Ptr....

	Let me start of by saying:  this isn't a compiler problem.
Recently, I've hit a minor problem in a couple of different places,
while working w/ library routines that need ptrs to functions.  
I can handle the obvious basics of passing an "appropriate" ptr.  
That is, a ptr to a function that exactly matches the indicated
prototype.  My problem is when I try to cast a ptr to a similar
fn.  For example:

	-  this is the prototype for the fn I want to pass:

	void newfn( u_int s, void *, void * )

	-  this is the prototype for the fn I'm supposed to use:

	void oldfn( int s, void *, void * )

	-  I "thought" a cast like this would work:

	((void) ((int), (void *), (void *))) newfn

	I've tried many different variations on the theme shown
above, but w/o success.  Usually, I get some sort of syntax
error saying I have mis-matched parens.  This isn't a compiler
problem, bec I've encountered something similar usg different
compilers (for different projs), but always wind up having to 
modify newfn, as a workaround, since I can't figure the correct 
way to cook up the desired cast.  (BTW, I'm using a dumb editor
to enter the cast shown above, so disregard any typing errors,
since the mailer's editor doesn't do brace checking....)

	I've looked high and low, in source code and documentation,
for examples, but I haven't seen anything that will help.  (It's
amazing that after earning my living writing C code for over
ten years that something like this shud still hang me up.)

	Thanx in advance for any incoming answers.    Jet




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