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From: am@cl.cam.ac.uk (Alan Mycroft)
Newsgroups: comp.lang.c
Subject: Re: enum - enum ?
Message-ID: <726@jenny.cl.cam.ac.uk>
Date: Fri, 12-Jun-87 07:46:38 EDT
Article-I.D.: jenny.726
Posted: Fri Jun 12 07:46:38 1987
Date-Received: Sun, 21-Jun-87 15:01:09 EDT
References: <139@starfire.UUCP> <5959@brl-smoke.ARPA>
Reply-To: am@cl.cam.ac.uk (Alan Mycroft)
Organization: U of Cambridge Comp Lab, UK
Lines: 21

In article <5959@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>As I recall, enums are now officially ints in disguise.

Hmm.  Checking in the draft (p54 para at line 40) seems to agree with this,
but lets consider:
   enum joke { a=0, b=999999999 };
what happens if 'int' is only 16 bits?  Does 'b == 999999999 & 0xffff'?
Similarly, consider
   enum { a = ~0U }
on a 32 bit two's complement machine.  What is 'a/2'? is it -1/2 (probably 0)
or 0x7fffffff?

Consider sizeof too: "The implementation many use the set of values ...
to allocate ... storage".
What does this mean for:
   enum query { zero=0, one=1 } q;
The spec. says zero is int hence
   sizeof(zero) = sizeof(int).
On the other hand sizeof(q) maay be sizeof(char).
Is this reasonable?
What about sizeof(q)?