Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!bu-cs!dartvax!eleazar.dartmouth.edu!shallit
From: shallit@eleazar.dartmouth.edu (Jeffrey Shallit)
Newsgroups: comp.lang.c
Subject: checking for overflow in C
Message-ID: <13367@dartvax.Dartmouth.EDU>
Date: 5 May 89 16:30:58 GMT
Sender: news@dartvax.Dartmouth.EDU
Reply-To: shallit@eleazar.dartmouth.edu (Jeffrey Shallit)
Organization: Dartmouth College, Hanover, NH
Lines: 9

Fans of C frequently boast that it is "very close to the machine".  Since
I'm a relative newcomer to the language, perhaps someone could enlighten
me about the officially approved way of checking overflow when multiplying
two integers.  Or is doing (i) a pre-multiply test to ensure the arguments
aren't too big or (ii) a post-division step to ensure the accuracy of the
result the only portable way of doing this?

Jeff Shallit
shallit@dartmouth.edu