3v4l.org

run code in 300+ PHP versions simultaneously
<?php $hashes = array_map(function ($num) { return substr(sha1($num), 0, 8); }, range(0, 100000)); print_r(array_slice($hashes, 0, 10)); if (array_unique($hashes) == $hashes) { echo 'all unique'; } else { echo 'collisions detected'; }
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40.38 ms | 402 KiB | 5 Q