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From: sparkman@hydra3c.cs.utk.edu (Donald Sparkman)
Newsgroups: comp.lang.c
Subject: Re: towards a faster isdigit()
Message-ID: <1991May14.192125.2460@cs.utk.edu>
Date: 14 May 91 19:21:25 GMT
References: <1991May8.030515.7004@twinsun.com>
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Reply-To: sparkman@hydra3c.cs.utk.edu (Donald Sparkman)
Organization: Univ of TN, Knoxville - CS Department
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As far as a faster isdigit if you can insure only ascii then 

#define isdigit(c) ((c^0x30)<10)

may be faster since its using bitwise Xor instead of cast and subtraction 

Don Sparkman