ID: 27052
User updated by: webmaster at armondc dot com
Reported By: webmaster at armondc dot com
Status: Bogus
Bug Type: Math related
Operating System: Windows 2000 Professional
PHP Version: 4.3.5RC2-dev
New Comment:
I do not see what RAND_MAX has to do with it, and excuse me if I'm
wrong here-
for($x = 0; $x < 15000; $x++) {
echo chr((rand(0,32768)%32)+65);
}
This code should replicate the problem on a unix-like platform, however
from my tests it doesn't.
Just trying to help :)
Previous Comments:
------------------------------------------------------------------------
[2004-01-26 20:06:10] [EMAIL PROTECTED]
RTFM:
Note: On some platforms (such as Windows) RAND_MAX is only 32768. If
you require a range larger than 32768, consider using mt_rand()
instead.
------------------------------------------------------------------------
[2004-01-26 20:03:17] webmaster at armondc dot com
I tried it on 4.3.5RC2-dev, and it's still relativly the same. The
pattern is slightly different, but is still as predictable as before.
------------------------------------------------------------------------
[2004-01-26 19:04:34] [EMAIL PROTECTED]
Please try using this CVS snapshot:
http://snaps.php.net/php4-STABLE-latest.tar.gz
For Windows:
http://snaps.php.net/win32/php4-win32-STABLE-latest.zip
Some rand() related bugs have already been fixed..
------------------------------------------------------------------------
[2004-01-26 15:56:22] webmaster at armondc dot com
On the "actual result" its not as easily spotted without wrapping.
This should give a better picture:
]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F
[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F
[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F
[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F
[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F
[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F
[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F
[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\
------------------------------------------------------------------------
[2004-01-26 15:53:26] webmaster at armondc dot com
Description:
------------
I'm not sure if this is a very major problem, or even a bug, but here
goes:
It seems rand() on Windows is very predictable.
I've tried it on 2 Windows Systems, and they were both predictable. It
showed a breif unpredictable segment, then followed by the same string
of characters over and over, and finally a few more unpredictable
characters.
I tried this on a FreeBSD 5.2 System, and it was unpreditable enough.
Seems to be a windows-only problem.
I also noticed bug#11108 - It seems similar, but the submitter was
using his own seeds, and I am using without.
Reproduce code:
---------------
<?php
// This will reproduce the problem
// on windows
for($x = 0; $x < 500; $x++) {
echo chr((rand()%32)+65);
}
// This is a quick-fix, but
// goes agaist the documentation's
// 'no need for srand()'
for($x = 0; $x < 500; $x++) {
srand(hexdec(substr(md5(microtime()), 0, 8)));
echo chr((rand()%32)+65);
}
?>
Expected result:
----------------
Something a bit random like:
HEOSITFS[ZYH_EVIVVXSLCWRHHC_]_L^PIBTC\TXPBWQLCM^VZSU`UHOG[\VF[KCDGFZM^Q\IG^KAIYPIYBSBIMGHXIBMPHLY\OAZMYAZPJ_`D`F\X\QXR[GP]DQLRHMYIOERBMEKBDJMJPN]J\\KPES^EGRKKO^S[`XL\SSHQXOYQU_JDMM`ZEUEOQOYMHJPYDTRRU_URHYJGXRQYDYADD]OBVUGC^GGSXPRJJAOAKRAYYN^Q\`XFQJNOWQKAJBFONFXNDZFFIMYRL`ROH^]IM_MINJI\MJJAVG`]_B_EAV`C\O_\DHCHLX_NIO`U^KMJF\`K]VZDOZ_FAWCZC_IQK^[NTPZCC]XEFZ[`\AG[PV^XLPRYVAS]ZPH`^WAXYAZYGK_M_QK`F]PRMP^BBPTRV^KV_VDOLFIM]WQNHVF^DYWGGSGLJ_ZMODG[Z_AAXBYD^FS\MITLZESC`DXLH]NWNIVWZZMVMSXFQMG[O[W[YSPVMTQLHD
Actual result:
--------------
An easily spotted pattern:
]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\YRWXENCTQJOP]F[LIBGHU^SDAZ_`MVK\
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/?id=27052&edit=1
