note 111931 added to function.crc32
| From: | JSatJavsSysdotOrg | Date: | Sat, 13 Apr 2013 16:22:09 +0000 |
| Subject: | note 111931 added to function.crc32 | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-194469@lists.php.net to get a copy of this message | ||
The khash() function by sukitsupaluk has two problems, it does not use all 62 characters from the
$map set and when corrected it then produces different results on 64-bit compared to 32-bit PHP
systems.
Here is my modified version :
<?php
/**
* Small sample convert crc32 to character map
* Based upon http://www.php.net/manual/en/function.crc32.php#105703
* (Modified to now use all characters from $map)
* (Modified to be 32-bit PHP safe)
*/
function khash($data)
{
static $map = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
$hash = bcadd(sprintf('%u',crc32($data)) , 0x100000000);
$str = "";
do
{
$str = $map[bcmod($hash, 62) ] . $str;
$hash = bcdiv($hash, 62);
}
while ($hash >= 1);
return $str;
}
//-----------------------------------------------------------------------------------
$test = array(null, true, false, 0, "0", 1, "1", "2", "3",
"ab", "abc", "abcd",
"abcde", "abcdefoo", "248840027", "1365848013", //
time()
"9223372035488927794", // PHP_INT_MAX-time()
"901131979", // mt_rand()
"Sat, 13 Apr 2013 10:13:33 +0000" // gmdate('r')
);
$out = array();
foreach ($test as $s)
{
$out[] = khash($s) . ": " . $s;
}
print "<h3>khash() -- maps a crc32 result into a (62-character) result</h3>";
print '<pre>';
var_dump($out);
print "\n\n\$GLOBALS['raw_crc32']:\n";
var_dump($GLOBALS['raw_crc32']);
print '</pre><hr>';
flush();
$pefile = __FILE__;
print "<h3>$pefile</h3>";
ob_end_flush();
flush();
highlight_file($pefile);
print "<hr>";
//-----------------------------------------------------------------------------------
/* CURRENT output
array(19) {
[0]=>
string(8) "4GFfc4: "
[1]=>
string(9) "76nO4L: 1"
[2]=>
string(8) "4GFfc4: "
[3]=>
string(9) "9aGcIp: 0"
[4]=>
string(9) "9aGcIp: 0"
[5]=>
string(9) "76nO4L: 1"
[6]=>
string(9) "76nO4L: 1"
[7]=>
string(9) "5b8iNn: 2"
[8]=>
string(9) "6HmfFN: 3"
[9]=>
string(10) "7ADPD7: ab"
[10]=>
string(11) "5F0aUq: abc"
[11]=>
string(12) "92kWw9: abcd"
[12]=>
string(13) "78hcpf: abcde"
[13]=>
string(16) "9eBVPB: abcdefoo"
[14]=>
string(17) "5TjOuZ: 248840027"
[15]=>
string(18) "5eNliI: 1365848013"
[16]=>
string(27) "4Q00e5: 9223372035488927794"
[17]=>
string(17) "6DUX8V: 901131979"
[18]=>
string(39) "5i2aOW: Sat, 13 Apr 2013 10:13:33 +0000"
}
*/
//-----------------------------------------------------------------------------------
?>
----
Server IP: 87.124.126.49
Probable Submitter: 212.159.72.30
----
Manual Page -- http://php.net/manual/en/function.crc32.php
Edit -- https://master.php.net/note/edit/111931
Del: integrated -- https://master.php.net/note/delete/111931/integrated
Del: useless -- https://master.php.net/note/delete/111931/useless
Del: bad code -- https://master.php.net/note/delete/111931/bad+code
Del: spam -- https://master.php.net/note/delete/111931/spam
Del: non-english -- https://master.php.net/note/delete/111931/non-english
Del: in docs -- https://master.php.net/note/delete/111931/in+docs
Del: other reasons-- https://master.php.net/note/delete/111931
Reject -- https://master.php.net/note/reject/111931
Search -- https://master.php.net/manage/user-notes.php