Xref:	news2.mv.net comp.os.msdos.djgpp:758
From:	Erik Max Francis <max AT alcyone DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: binary representation of floats
Date:	Fri, 02 Feb 1996 12:29:56 -0800
Organization:	&tSftDotIotE
Lines:	26
Message-ID:	<31127444.7DE259CD@alcyone.com>
References:	<DM34r9 DOT HtI AT granite DOT mv DOT net>
NNTP-Posting-Host:	newton.alcyone.com
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Eli Zaretskii wrote:

> Every book on Intel CPUs describes this.  To get a bit pattern of any
> float or double variable, cast them to an unsigned int and use the usual
> bit operations.  (In the case of double, you'll have to use long long.)

Correct me if I'm mistaken, Eli, but this won't work.  Casting a float or
double to an integer type will truncate the value so that it is the nearest
integer less than or equal to the float/double value.  That is, (unsigned int)
2.1f yields 2, not the binary representation of 2.1 in the machine's float.

What you have to do is cast a _pointer_ to that float or integer to a pointer
of an integral type of the same size.  That is, instead of

    (unsigned int) f, 

you need

    *(unsigned int *) &f.

-- 
Erik Max Francis, &tSftDotIotE. && max AT alcyone DOT darkside DOT com || max AT alcyone DOT com
San Jose, California, U.S.A. && 37 20 07 N 121 53 38 W && the 4th R is respect
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