Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!rpi!uupsi!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Special character constants
Message-ID: <14973@smoke.brl.mil>
Date: 25 Jan 91 17:10:59 GMT
References: <1292@mti.mti.com> <1991Jan16.174248.2689@zoo.toronto.edu> <1063@mwtech.UUCP>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 19

In article <1063@mwtech.UUCP> martin@mwtech.UUCP (Martin Weitzel) writes:
>Hey, wait a moment here. If we drive this to the extreme, can we really
>depend on spaces to produce certain visible space on some output device?

No, but it is a reasonable thing to expect.
The C standard is simply not in a position to dictate the detailed
characteristics of external devices.  It does require that distinct
code values be provided for representing a certain set of characters
both at compile time and at run time, but there is no requirement
that even the "graphic" characters have any particular glyphs on
actual devices.  (They could be holes in a punched card or paper tape.)
Control characters are even more difficult to rely on; the C standard
stipulates what the "intended" effect of them is, but a conforming
implementation may be deficient in its support of these intentions.

>What is the *least* the programmer can depend on? Can he or she depend on
>certain results of `printf("hello, world\n");'

No, the user may not understand English.