ID: 45301
Comment by: scott046 at hotmail dot com
Reported By: payton2558 at googlemail dot com
Status: Assigned
Bug Type: Math related
Operating System: win32 only
PHP Version: *
Assigned To: pajoye
New Comment:
If anybody is interested, this code:
<?php
print("20 element array; apparently no problem<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 20) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n200 element array; apparently no
problem<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 200) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n2000 element array; apparently no
problem<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 2000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n10000 element array; apparent problem: mild
repetition<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 10000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n20000 element array; apparent problem:
repetition<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 20000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n30000 element array; apparent problem:
repetition<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 30000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n50000 element array; apparent problem:
repetition<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 50000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n100000 element array; 32767=2^15-1 repeating;
<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 100000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n200000 element array; 32767=2^15-1 repeating;
<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 200000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
print("<br>\r\n<br>\r\n300000 element array; 32767=2^15-1 repeating;
<br>\r\n");
$array1 = array();
$counter1 = 0;
while($counter1 < 300000) {
$array1[] = $counter1;
$counter1++;
}
$print_counter1 = 0;
while($print_counter1 < 10) {
print($array1[array_rand($array1)] . "<br>\r\n");
$print_counter1++;
}
?>
produces this output:
20 element array; apparently no problem
16
5
11
9
17
7
15
2
8
9
200 element array; apparently no problem
43
25
147
127
127
2
109
14
67
165
2000 element array; apparently no problem
26
1513
1882
1721
590
917
1237
596
409
1170
10000 element array; apparent problem: mild repetition
2661
6633
8864
1157
2432
6681
6995
6633
8864
1157
20000 element array; apparent problem: repetition
2432
13677
15498
3590
13677
15498
3590
13677
15498
3590
30000 element array; apparent problem: repetition
13677
15498
3590
13677
15498
3590
13677
15498
3590
13677
50000 element array; apparent problem: repetition
19089
29176
3590
29176
3590
29176
3590
29176
3590
29176
100000 element array; 32767=2^15-1 repeating;
3590
32767
32767
32767
32767
32767
32767
32767
32767
32767
200000 element array; 32767=2^15-1 repeating;
32767
32767
32767
32767
32767
32767
32767
32767
32767
32767
300000 element array; 32767=2^15-1 repeating;
32767
32767
32767
32767
32767
32767
32767
32767
32767
32767
for me. I do not know the exact problem although the randomization
seems progressively worse on larger arrays.
Previous Comments:
------------------------------------------------------------------------
[2008-07-02 11:47:39] j...@php.net
See also bug #45302
------------------------------------------------------------------------
[2008-06-18 21:26:39] paj...@php.net
> What about merging a patch that circulated in @internals that made
> rand() and alias to mt_rand() and be done with this ?
Because it may not fix the problem? (see the other report today and two
weeks ago).
------------------------------------------------------------------------
[2008-06-18 21:04:23] crrodriguez at suse dot de
What about merging a patch that circulated in @internals that made
rand() and alias to mt_rand() and be done with this ?
------------------------------------------------------------------------
[2008-06-18 19:40:10] payton2558 at googlemail dot com
Here's the shortest version. Try varying the array_fill num parameter.
Lower numbers appear to increase the randomness.
Appears problem is array_rand interfering with the random seed but
please investigate further than that as I'm certain I experienced this
problem before ever using array_rand (rand(0,count($a)-1) works in its
place and doesn't trigger bug in this example).
<?php
$a = array_fill(0, 100000, "word");
for ($i=0; $i<20; $i++) {
array_rand($a);
echo rand(1,9999)."\n";
}
?>
------------------------------------------------------------------------
[2008-06-18 18:06:09] sv4php at fmethod dot com
Confirmed on Apache 2.2, Windows XP SP2 with PHP 5.2.6.
Confirmed also without building files (just building the array directly
in a loop).
Requires Windows, doesn't seem to affect mt_rand();
------------------------------------------------------------------------
The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
http://bugs.php.net/45301
--
Edit this bug report at http://bugs.php.net/?id=45301&edit=1
