<?php

// Compatibility function
// http://www.pgregg.com/projects/php/code/str_rotN.php
// Author: Paul Gregg

show_source(__FILE__);

// Generic rotate by any number
function rot_n($str, $num=13) {
  return preg_replace('/([a-z])/ei', 'chr(((ord(\'$0\')-(ord(\'$0\')>96?97:65)+$num)%26)+(ord(\'$0\')>96?97:65))', $str);
}

// Standard rot13 function
if (!function_exists('str_rot13')) {
  Function str_rot13($str) {
    return preg_replace('/([a-z])/ei', 'chr(((ord(\'$0\')-(ord(\'$0\')>96?97:65)+13)%26)+(ord(\'$0\')>96?97:65))', $str);
  }
}


$str = "Hello World.\n";

echo '<hr>', $str;
echo '<br>', str_rot13($str);
echo '<br>', rot_n($str);
?>