Split a string by string (like explode()) backwards. See http://stackoverflow.com/q/16610791/216129

backward_explode.php

<?php

/**
 * Split a string by string (like explode()) backwards.
 *
 * @param string $delimiter <p>The boundary string</p>
 * @param string $string <p>The input string</p>
 * @param int $limit <p>
 * If limit is set and positive, the returned array will contain
 * a maximum of limit elements counting from the end of the string with the first
 * element containing the rest of string (from the beginning).
 * </p>
 * <p>
 * If the limit parameter is negative, all components
 * except the first -limit are returned.
 * </p>
 * <p>
 * If the limit parameter is zero, then this is treated as 1.
 * </p>
 * @param bool $keep_order If true, array elements are in the same order as they appear in the text; if false the order is reversed
 * @return array If delimiter is an empty string (""),
 * explode will return false.
 * If delimiter contains a value that is not
 * contained in string and a negative
 * limit is used, then an empty array will be
 * returned. For any other limit, an array containing
 * string will be returned.
 * @see explode()
 */
function backward_explode($delimiter, $string, $limit = null, $keep_order = true) {
    if ((string)$delimiter === "") {
        return false;
    }

    if ($limit === 0 || $limit === 1) {
        return array($string);
    }

    $explode = explode($delimiter, $string);

    if ($limit === null || $limit === count($explode)) {
        return $keep_order? $explode : array_reverse($explode);
    }

    $parts = array();

    if ($limit > 0) {
        for ($i = 1; $i < $limit; $i++) {
            $parts[] = array_pop($explode);
        }
        $remainder = implode($delimiter, $explode);
        $parts[] = $remainder;
        if ($keep_order) {
            $parts = array_reverse($parts);
        }
    } else {
        if (strpos($string, $delimiter) === false) {
            return array();
        }
        $parts = $explode;
        array_splice($parts, 0, abs($limit));
        if (!$keep_order) {
            $parts = array_reverse($parts);
        }
    }

    return $parts;
}