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
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Message-ID: <31127444.7DE259CD@alcyone.com>
References: <DM34r9 DOT HtI AT granite DOT mv DOT net>
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To: djgpp AT delorie DOT com
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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
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