On two different servers I found that crc32() relates to hash('crc32b',)
This may be good to know if you are writing a crc32_file function based on hash_file.
(The example does not compensate for negative crc32 results)
<?php
$val = 'hello';
var_dump(crc32($val) == ( '0x' . hash('crc32b', $val) ) ); var_dump(crc32($val) == ( '0x' . hash('crc32', $val) ) ); ?>
Also if you are looking for a way to reduce collisions and still keep the hash result small (smaller than say md5) you could get a nice database friendly 64 bit value by using hash/crc32 and hash/crc32b, which is slower than a single md5 but the result may be more suitable for certain tasks.
<?php
$val = 'hello';
$crc64 = ( '0x' . hash('crc32', $val) . hash('crc32b', $val) ) );
var_dump($crc64); var_dump($crc64 + 0); ?>
(examples tested on php 5.2.17)
note: ('0x' . $hex . + 0) is faster than base_convert($hex,16,10)
