note 109662 added to function.crc32

The crc32() function can return a signed integer in certain environments. Assuming that it will always return an unsigned integer is not portable. I created a sample code here and ran it off a random virtual server. Do note the output may vary according to your environment but it is sufficient to illustrate the possible outcomes. <?php $checksum = crc32("The quick brown fox jumped over the lazy dog."); $divisor = 256; $a = $checksum; echo "Original crc32 output a = $a, to divide by $divisor\n"; $r = $a % $divisor; echo "% operator: r = $r \n"; $r = intval(fmod($a, $divisor)); echo "fmod function: r = $r \n"; $r = bcmod($a, $divisor); echo "bcmod function: r = $r \n"; echo "\n"; $a = sprintf("%u", $checksum); echo "sprintf crc32 output a = $a, to divide by $divisor\n"; $r = $a % $divisor; echo "% operator: r = $r \n"; $r = intval(fmod($a, $divisor)); echo "fmod function: r = $r \n"; $r = bcmod($a, $divisor); echo "bcmod function: r = $r \n"; ?> Output: Original crc32 output a = -2103228862, to divide by 256 % operator: r = -190 fmod function: r = -190 bcmod function: r = -190 sprintf crc32 output a = 2191738434, to divide by 256 % operator: r = 255 fmod function: r = 66 bcmod function: r = 66 Conclusion: Depending on your desired behavior, you should probably use sprintf() on the result or the generic hash() instead. Also note that integer arithmetic operators do not have the precision to work correctly with the integer output. ---- Server IP: 69.147.83.197 Probable Submitter: 220.255.2.158 ---- Manual Page -- http://www.php.net/manual/en/function.crc32.php Edit -- https://master.php.net/note/edit/109662 Del: integrated -- https://master.php.net/note/delete/109662/integrated Del: useless -- https://master.php.net/note/delete/109662/useless Del: bad code -- https://master.php.net/note/delete/109662/bad+code Del: spam -- https://master.php.net/note/delete/109662/spam Del: non-english -- https://master.php.net/note/delete/109662/non-english Del: in docs -- https://master.php.net/note/delete/109662/in+docs Del: other reasons-- https://master.php.net/note/delete/109662 Reject -- https://master.php.net/note/reject/109662 Search -- https://master.php.net/manage/user-notes.php