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From: mar@hpclla.UUCP
Newsgroups: comp.lang.c
Subject: Re: enum - enum ?
Message-ID: <4400002@hpclla.HP.COM>
Date: Mon, 8-Jun-87 19:47:48 EDT
Article-I.D.: hpclla.4400002
Posted: Mon Jun  8 19:47:48 1987
Date-Received: Sat, 13-Jun-87 04:39:16 EDT
References: <139@starfire.UUCP>
Organization: Hewlett-Packard CLL
Lines: 31


>I think it would be reasonable for enum - enum to be an integer value,
>just as ptr - ptr is, and for similar reasons; you want the 'distance'
>between them.  This would also imply  enum + int  == enum  and  enum++ is ok

The following statements assume the declaration: 
			enum color {red=1, blue=4, green=5};
			enum fruit {apple=1, orange=4, grape=5};

for clarification: color is an enum; red is an enum constant;

What is the use of an expression such as red++  ??

Enum constants are integer constants - why would you want to allow the 
modification of a constant (ie: red++) - might as well use ints.

I agree that enums in general should be implemented as a special case of
integers - allowed wherever integer constants are allowed, but with extra
restrictions regarding assignment of two different enums (color = fruit)
and addition of enums or enum constants.

Subtracting two enum constants or adding a integer to an enum constant could 
be useful, but what would you use the addition of two enum constants for?

Should enum_constant - enum_constant only be allowed if both enum constants
are elements of the same enum type?

I would like to have enums and enum constants be flexible, but I also would
like the extra type-checking for enums; otherwise I might as well use
#define's for compile-time constants.
type.