Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!unmvax!indri!aplcen!haven!adm!smoke!gwyn From: gwyn@smoke.BRL.MIL (Doug Gwyn) Newsgroups: comp.lang.c Subject: Re: Dumb question: What IS a trigraph? Message-ID: <10762@smoke.BRL.MIL> Date: 17 Aug 89 15:09:42 GMT References: <3566@uwovax.uwo.ca> Reply-To: gwyn@brl.arpa (Doug Gwyn) Organization: Ballistic Research Lab (BRL), APG, MD. Lines: 14 In article <3566@uwovax.uwo.ca> 2014_5001@uwovax.uwo.ca writes: >Every so often someone mentions a trigraph. What is a trigraph??? There's one (the "???"). Standard C requires that, very early in the phases of translation, certain sequences of three source characters starting with "??" be mapped into equivalent single characters. This is intended to allow C programs to be expressed entirely using the ISO-646 basic character set, which does not include {, |, and several other essential C source characters. It is not expected that real programming environments would ever require programmers to type these trigraph sequences; they're intended primarily for program interchange among different sites. Unless you're importing a lot of code from European sites or are implementing a C compiler, you shouldn't have to be concerned about trigraphs, since you'll never use nor see them.