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From: richard@aiai.ed.ac.uk (Richard Tobin)
Newsgroups: comp.lang.c
Subject: Re: need isnan and isinf src for microsoft c
Message-ID: <4566@skye.ed.ac.uk>
Date: 29 Apr 91 15:19:15 GMT
References: <1991Apr22.173940.25021@solo.csci.unt.edu>
Reply-To: richard@aiai.UUCP (Richard Tobin)
Organization: AIAI, University of Edinburgh, Scotland
Lines: 19

In article <1991Apr22.173940.25021@solo.csci.unt.edu> gene@ponder.csci.unt.edu (Gene De Lisa) writes:
>Could someone tell me how to detect NaN and infinite numbers

Infinities have the exponent set to its maximum value and the mantissa
zero.  NaNs have the same exponent but a non-zero mantissa.

For single precision the format is sign bit, 8 bit exponent, 23 bit mantissa.
For double precision the numbers are 11 and 52.

>in microsoft c?

Assuming it uses IEEE format, as above, but you have to be careful
about byte order.

-- Richard
-- 
Richard Tobin,                       JANET: R.Tobin@uk.ac.ed             
AI Applications Institute,           ARPA:  R.Tobin%uk.ac.ed@nsfnet-relay.ac.uk
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