Clean up posted data

clean.php

<?php

/**
 * Cleans up posted data - trims texts & converts empty fields to null.
 * 
 * @param mixed[] $post POST data to be cleaned.
 * @return mixed[] Cleaned-up POST data.
 */
function clean($post)
{
    foreach ($post as $key=>$val) if (is_string($val)) $post[$key] = trim($val);
    foreach ($post as $key=>$val) if ($val === '') $post[$key] = null;
    return $post;
}