Path: utzoo!utgpu!attcan!uunet!husc6!bloom-beacon!gatech!psuvax1!blitz.cs.psu.edu!flee
From: flee@blitz.cs.psu.edu (Felix Lee)
Newsgroups: comp.lang.c
Subject: Is range(ptrdiff_t) > range(size_t)?
Message-ID: <3740@psuvax1.cs.psu.edu>
Date: 27 Jul 88 20:06:30 GMT
Sender: news@psuvax1.cs.psu.edu
Organization: Penn State University Computer Science
Lines: 13

Harbison&Steele (2e) says (p. 156)
> Some implementations of C use int or long int as the type of the
> result of sizeof, but this is an inferior choice because it may be
> impossible to represent the size of a very large array, say one that
> spans more than half the total address space.

But such a large array breaks ptrdiff_t.  Is ptrdiff_t required to
have a larger range than size_t?  Can you stuff a size_t value into a
ptrdiff_t variable without overflow?  Is the following relationship
always true?
	sizeof(char a[]) == &a[sizeof(a)] - &a[0]
--
Felix Lee	*!psuvax1!flee