Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!usc!apple!motcsd!hpda!hpcupt1!swh
From: swh@hpcupt1.HP.COM (Steve Harrold)
Newsgroups: comp.lang.c
Subject: Re: Dumb question: What IS a trigraph?
Message-ID: <5940008@hpcupt1.HP.COM>
Date: 17 Aug 89 15:02:16 GMT
References: <3566@uwovax.uwo.ca>
Organization: Hewlett Packard, Cupertino
Lines: 14

Re: Trigraphs

Poster suggests that trigraphs are not likely to be met in "everyday" C
code, but I'd like to caution you that they will show up in some very
unexpected ways.

For example, say you have a string literal in your code that reads something
like "...Are you sure you want to do this??.....".  The inncocent pairing
of the two question marks will cause the Ansi-conformant compiler to hunt
for a trigraph.  If the character immediately following the "??" completes
a legal trigraph, your string is no longer what you thought it was.

The compilation will succeed without comment, but your run-time results
may vary.