Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ucsd!sdcsvax!ucsdhub!isg100!nusdhub!rwhite
From: rwhite@nusdhub.UUCP (Robert C. White Jr.)
Newsgroups: comp.lang.c
Subject: Re: When is a cast not a cast?
Message-ID: <1332@nusdhub.UUCP>
Date: 3 May 89 22:02:10 GMT
References: <2747@buengc.BU.EDU>
Organization: National University, San Diego
Lines: 22

in article <2747@buengc.BU.EDU>, bph@buengc.BU.EDU (Blair P. Houghton) says:
[p and c are of type (char *)]
> 10 	p = (c + (char *) i);  /* More trouble than it's worth... */

and totally inaccurate too boot.  The + operator is defined separately for
the addition of a pointer-to-type and and interger.  The specs indicate
that you will get the operation p=c+(i*sizeof_typeof_c) so the cast is
in error.  pointer + interger is legal.  if you had an array of structures
anmed "strarray" and you set a pointer to the Nth entry, and you wanted
to get to the N+Mth entry the following code is legal and correct:

structure somestruct strarry[1000], *ptr;
ptr = strarry[N];
...
ptr = ptr + M; /* or ptr += M */
...


[Unless, of course, I am brain dammaged and therefore not correct in
interpreting this stuff]

Rob.