Path: utzoo!attcan!uunet!ingr!crossgl
From: crossgl@ingr.UUCP (Gordon Cross)
Newsgroups: comp.lang.c
Subject: Re: Why unsigned chars not default?
Summary: treatment of "char" is implementation defined
Message-ID: <2723@ingr.UUCP>
Date: 24 Oct 88 21:42:30 GMT
Organization: Intergraph Corp. Huntsville, Al
Lines: 21

In article <9563@pur-ee.UUCP>, mendozag@pur-ee.UUCP (Grado) writes:
> 
>   However, much to his dismay, other compilers (LSC, MSC, and Unix)
>  require him to declare as unsigned char the I/O buffer (which he
>  also uses for arithmetic operations) else the chars are negative
>  numbers when the their contents represents value > 127. (He does
>  a lot of arithmetic with characters representing integers).
> 

The proposed ANSI C standard states (I am quoting directly from the document):

"   An object declared as a character (char) is large enough to store any
 member of the required source charcater set [ .. ].  If such a character is
 stored in a char object, its value is guaranteed to be non-negative.  If other
 quantities are stored in a char object, the behavior is implementation
 defined:  the values are treated as either signed or non-negative integers."

Basically, this allows each complier writer to explore his whims.  Hope it
helps!

                               Gordon Cross