Creating short URLs/hashes

gistfile1.aw

<?php

  function getHash( $n = '' ) {

    if( $n == '' ) {
      $n = rand();
    }

    $codeset = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    $base = strlen($codeset);
    $converted = "";

    while ($n > 0) {
      $converted = substr($codeset, ($n % $base), 1) . $converted;
      $n = floor($n/$base);
    }

    return $converted;
  }

  function reverseHash( $hash ) {

    $n = 0;
    $codeset = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

    for( $i = strlen($hash); $i; $i-- ) {
      $n += strpos($codeset, substr($hash, (-1 * ( $i - strlen($hash) ) ), 1 ) )
        * pow( strlen($codeset), $i-1 );
    }

    return $n;
  }
?>