http://www.perlmonks.org?node_id=1019249

edwyr has asked for the wisdom of the Perl Monks concerning the following question:

I know floats and doubles are IEEE. How do I convert the float (four bytes) to hex. I need the next for a project I'm working on where numbers are not convenient. (i.e. 1 / 7 = 0.142857142857143 = 0x6FDF1234 ($whatever)) Mike

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Re: Float/double to hex?
by BrowserUk (Patriarch) on Feb 18, 2013 at 01:27 UTC
    1 / 7 = 0.142857142857143 = 0x6FDF1234

    That hex value doesn't correspond to either a float or double in IEEE format? 

    print unpack 'h*', pack 'f', 1/7;;
529421e3

print unpack 'h*', pack 'd', 1/7;;
2942942942942cf3

    [download]
    With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
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[d/l]
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[d/l]

        I've no idea what that hex value is, but it certainly isn't any IEEE representation of 1/7.

        With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
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        HA! I completely got fooled by wolfraudalpha
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Re: Float/double to hex?
by Anonymous Monk on Feb 18, 2013 at 00:45 UTC
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Re: Float/double to hex?
by Athanasius (Archbishop) on Feb 19, 2013 at 04:53 UTC

    Like the other monks, I’m not clear on the question being asked here. However, if floating point numbers in hexadecimal notation are wanted, Data::Float may be what you’re looking for:

    #! perl
use strict;
use warnings;
use Data::Float qw( float_hex hex_float );

my $n = 1 / 7;
my $h = float_hex($n);
my $d = hex_float($h);

print "fraction =    $n\nhex      = $h\ndecimal  =    $d\n";

    [download]

    Output:

    14:46 >perl 538_SoPW.pl
fraction =    0.142857142857143
hex      = +0x1.2492492492492p-3
decimal  =    0.142857142857143

14:47 >

    [download]

    Hope that helps,

    Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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      I want to do some text analysis of stock data. I cannot do what I want using numbers, only alpha or hex. I want to convert the numbers to the four byte hex representation of a float (or eight bytes for a double). I didn't think to check CPAN. I'll try the above code. Thanks to all that replied. Mike
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        I know a float is a four byte value. I want to have the hex string representation of those four bytes. If (2**16) is 65536, I want 65536 to be 0x0000ffff (or 0xffff0000, whatever order). Mike
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