Newsgroups: comp.lang.c
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: trigraphs (was Why are character arrays special)
Message-ID: <1989Feb19.060311.9533@utzoo.uucp>
Organization: U of Toronto Zoology
References: <19742@uflorida.cis.ufl.EDU> <225800126@uxe.cso.uiuc.edu> <1875@dataio.Data-IO.COM> <15941@mimsy.UUCP> <9650@smoke.BRL.MIL>
Date: Sun, 19 Feb 89 06:03:11 GMT

In article <9650@smoke.BRL.MIL> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>Note that trigraphs may best be dealt with by a separate translator,
>ideally a separate program that could practically be skipped except
>the first time that code is imported from another site...

And let us not forget that in a Unix-like environment, a reasonably (not
wonderfully, but reasonably) efficient implementation of such a translator
is the following:

	#! /bin/sh
	sed "/??/ {
		s/??=/#/g
		s/??(/[/g
		s;??/;\\\\;g
		s/??)/]/g
		s/??'/^/g
		s/??</{/g
		s/??!/|/g
		s/??>/}/g
		s/??-/~/g
		}" $*

The one possible problem here is that old implementations of sed may have
annoyingly low limits on input line length.
-- 
The Earth is our mother;       |     Henry Spencer at U of Toronto Zoology
our nine months are up.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu