Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!pyramid!thirdi!peter
From: peter@thirdi.UUCP (Peter Rowell)
Newsgroups: comp.lang.c
Subject: type casting
Message-ID: <400@thirdi.UUCP>
Date: 27 Apr 88 20:48:17 GMT
Reply-To: peter@thirdi.UUCP (Peter Rowell)
Organization: Third Eye Software, Inc., Menlo Park, CA
Lines: 33
Keywords: type casting


I have two questions regarding type casting.  Both of them arise from
the need to improve the appearance of some code, probably using
#define's.  It is important that the code compile on a *very* wide
assortment of machines/compilers with no compile errors and no
lint errors.

1)	Is type casting of the left hand side of an expression supported
	in ANSI C?  Any place other than BSD?
	E.g.  int *pfoo; (char *)pfoo = malloc(10*sizeof(pfoo[0]));

2)	Is it possible to use a variable in such a way as to imply its
	type for casting purposes?
	E.g.  int *pfoo; pfoo = (typeof(pfoo)) malloc(10*sizeof(pfoo[0]));


We would like to do something like:
	#define AdjustArray(arr,cnt) \
		((char *)arr = realloc((char *)arr, cnt * sizeof(arr[0])))
OR
	#define AdjustArray(arr,cnt) \
		(arr = (typeof(arr)) realloc((char *)arr, cnt * sizeof(arr[0])))

and then replace
	pfoo = (int *) realloc((char *)pfoo, new_size * sizeof(pfoo[0]));
with
	AdjustArray(pfoo, new_size);


Replies by mail, please.

	Peter Rowell
	Third Eye Software, Inc.
	(415) 321-0967