From: "Mark J. Reed" <mreed@...>
Date: 2004-02-26T00:24:54+09:00
Subject: Re: hex to float conversion

paul.rogers@shaw.ca (Paul) writes:

>I have a hex number that I need to convert to a 32 bit float

>eg  0x44361000 => 728.25  (from
>http://sandbox.mc.edu/~bennet/cs110/flt/ftod.html)

>Ive written some ugly code to do it, but Im sure there must be a nicer
>way with pack/unpack/sprintf

If you have the original hex in a string, you'll need to convert it to
an int first.  Then you have to put it in an array, call pack on the array,
and call unpack on the resulting string.  What you get out of that is
again an array so you need to extract the element you want.  The
whole thing looks like this:

irb(main):001:0> s='0x44361000'
=> "0x44361000"
irb(main):002:0> f=[s.to_i(16)].pack('L').unpack('F')[0]
=> 728.25

Going the other way is similar:

irb(main):003:0> sprintf("0x%08x", [f].pack('F').unpack('L')[0])
=> "0x44361000"

-Mark