ID:               12455
 Comment by:       marriage-interracial41 at hotmail dot com
 Reported By:      sulka at sulake dot com
 Status:           Bogus
 Bug Type:         *Math Functions
 Operating System: All
 PHP Version:      4.0.4pl1, 4.0.6
 New Comment:

<a href=http://adultupskirt-footi.da.ru>marriage interracial</a>


Previous Comments:
------------------------------------------------------------------------

[2001-07-31 12:10:08] [EMAIL PROTECTED]

open -> bogus

------------------------------------------------------------------------

[2001-07-31 12:09:38] [EMAIL PROTECTED]

OK, well can you check to see that microtime() is working for you? This
script should print out 100.

<?php
$a = array();
for($i=0; $i<100; $i++)
{
  $a[((double)microtime()*1000000)]= 1;
}

echo count($a), "\n";
?>

BTW, your most recent example (calling a "remote" script) is
essentially the same as calling the local function pwd(). You still are
re-seeding the PRNG with each time you call the function. In order to
produce a pseudo-random sequence you should only seed the PRNG once.
This is a hard thing to do in the case where you generate one random
number from the sequence per execution.

Here is something that works for me even though I call the srand()
function inside the function (though the randomness is probably pretty
poor). You might be able to adapt it in some way for your use. The idea
here is that once you shuffle the array once, you use that as the
starting point for the next shuffle.

<?php
$pass_array =
array('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',0,1,2,4,5,6,7,8,9);

function pwd(&$pass_array) {
  srand ((double)microtime()*1000000);
  $password = '';
  shuffle(&$pass_array);
  for ($i=0; $i<6; $i++) { $password .= $pass_array[$i]; }
  return $password;
}

$a = array();
for($i=0; $i<500; $i++) {
        $a[pwd($pass_array)] = 1;
}

echo count($a), "\n";

This is not a *bug* (IMHO). This is a problem with your script, you
might want to try this discussion on [EMAIL PROTECTED] and see
if people have more suggestions for you.

------------------------------------------------------------------------

[2001-07-31 10:20:27] sulka at sulake dot com

Ok, here's sample code that should wake you up. The problem 
occurs even when srand is only called once / page load.

Create two PHP pages:

password.php

<?PHP
$password = "";
$array = 
array('a','b','c','d','e','f','g','h','i','j','k','l','m','
n','o','p','q','r','s','t','u','v','w','x','y','z',0,1,2,4,
5,6,7,8,9);
srand ((double)microtime()*1000000);
shuffle(&$array);
for ($i=0; $i<6; $i++) { $password .= $array[$i]; }
echo $password;?>

load100times.php

<?PHP
$i=0;
while($i<100) {
        $file = fopen ("http://localhost/password.php";, "r");
    $password = fgets ($file, 128);
        fclose($file);
    $a[$password] = $password;
    $i++;
        }
echo "Count: " . count($a);
?>

Then load the load100times.php in your browser. The result 
should be 100 but is still 4 on the machines I'm testing 
on. I'm assuming srand is not ment to be run only once / 
server start?


------------------------------------------------------------------------

[2001-07-31 10:00:28] [EMAIL PROTECTED]

Try moving your srand() call outside of the pwd() function. That should
fix it. The posted script returns 4 for me on Solaris 5.8, and 500 when
I move the srand() outside of pwd().

srand() should only be called *once*.

Reopen this if that does not fix it.

------------------------------------------------------------------------

[2001-07-30 06:25:27] sulka at sulake dot com

The same problem also occurs on PHP 4.0.6 on Darwin/PPC. 
System info:

PHP Version 4.0.6
System: Darwin localhost 1.3.7 Darwin Kernel Version 1.3.7: 
Sat Jun��9 11:12:48 PDT 2001; 
root:xnu/xnu-124.13.obj~1/RELEASE_PPC��Power Macintosh 
powerpc
Configure Command   './configure' '--with-mysql=/usr/local' 
'--with-apxs=/usr/sbin/apxs' '--with-zlib=/usr'
Server API: Apache
Apache Version: Apache/1.3.20


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