Comment on Tutorial - Convert a hex string into a 32-bit IEEE 754 float number in PHP By Julian L



Comment Added by : Mark

Comment Added at : 2015-02-02 14:42:56

Comment on Tutorial : Convert a hex string into a 32-bit IEEE 754 float number in PHP By Julian L
My code:

$hex=array('C4028000','457F9000','2D7F5','0002D7F5','47D9F95E','000040E4');

foreach($hex as $h){
echo $h.'='.hexTo32Float($h).'<br>';
}

function hexTo32Float($strHex) {
$v = hexdec($strHex);
$x = ($v & ((1 << 23) - 1)) + (1 << 23) * ($v >> 31 | 1);
$exp = ($v >> 23 & 0xFF) - 127;
return $x * pow(2, $exp - 23);
}

This outputs:

C4028000=522
457F9000=4089
2D7F5=6.0080426430695E-39
0002D7F5=6.0080426430695E-39
47D9F95E=111602.734375
000040E4=5.8891109391561E-39

The first output differs from yours as it is positive. The other values match yours. However, the last one (000040E4=5.8891109391561E-39) doesn't agree with http://babbage.cs.qc.cuny.edu/IEEE-754/index.xhtml, which tells me the decimal value of 000040E4 is 2.3278370089363861182184995837612086772827711378452680000428418331977209465577516311896033585071563720703125E-41

And http://babbage.cs.qc.cuny.edu/IEEE-754.old/32bit.html tells me it should be: 2.327837008936386e-41

Is this an error in the function or an error on the other site?

Cheers,
Mark.


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Archived Comments

1. your code helps a lot.....
thanx......

View Tutorial          By: beh at 2009-08-19 06:06:20

2. so how can i run this project
View Tutorial          By: milinda at 2010-12-17 10:01:23

3. Hi..
i a'm Sajid mestri (Maha,sangli)

View Tutorial          By: sajid at 2010-10-30 00:32:15

4. Thank you for this useful script! It works very we
View Tutorial          By: Giuseppe at 2010-12-09 05:35:43

5. Ku is quite correct. When you create any object, i
View Tutorial          By: Avnish at 2010-10-28 04:00:20

6. Good Example esp. way it was presented.
View Tutorial          By: Arunlal at 2013-06-20 11:56:43

7. How to find port names in pc? like COM1 etc ? i wn
View Tutorial          By: layiba at 2013-12-25 08:28:30

8. Nice guidelines which provide to understand struts
View Tutorial          By: harshal patel at 2010-08-13 04:59:16

9. please provide web.xml for this application.
View Tutorial          By: vandana at 2010-03-10 02:08:05

10. Hello,
Thank you very much for this sample

View Tutorial          By: Alex at 2010-08-12 07:30:32