functions.inc.php

<?php
// library of shared functions

/* This function returns twice its argument, but leaves
 * original value unchanged since call is by value.
 */
function twice( $x ) {
  $x *= 2;
  return $x;
}

/* This function returns no value.  It uses call by reference
 * to double its argument.
 */
function double( &$x ) {
  $x *= 2;
}
?>