PHP Functions for parsing & building query strings, in a better way than http_build_query or parse_str does.

php-query-string.php

<?php

function ParseQueryString($query, $orig = false) {
    $items = $orig ? $orig : array();
    $_items = explode('&', $query);
    foreach ($_items as $item) {
        if (strpos($item, '=')===false) {
            $items[urldecode($item)] = true;
        }
        else {
            $itemp = explode('=', $item);
            $key = urldecode($itemp[0]);
            if (substr($key, -2)=='[]')
                $items[substr($key, 0, -2)][] = urldecode($itemp[1]);
            else
                $items[$key] = urldecode($itemp[1]);
        }
    }
    return $items;
}
function BuildQueryString($items) {
    $queryItems = array();
    foreach ($items as $name => $val) {
        if ($val===false) {
            continue;
        } elseif ($val===true) {
            $queryItems[] = urlencode($name);
        } elseif (is_array($val)) {
            foreach ($val as $_val) {
                $queryItems[] = urlencode($name).'[]='.urlencode($_val);
            }
        } else {
            $queryItems[] = urlencode($name).'='.urlencode($val);
        }
    }
    return implode('&', $queryItems);
}
function AppendQueryString($url, $queryValues) {
    $_qMarkPos = strpos($url, '?');
    $existingQuery = $_qMarkPos === false ? false : substr($url, $_qMarkPos + 1);
    $baseURL = $_qMarkPos !== false ? substr($url, 0, $_qMarkPos) : $url;
    $items = array();
    if ($existingQuery)
        $items = ParseQueryString($existingQuery);
    $queryValues = is_array($queryValues) ? BuildQueryString($queryValues) : $queryValues;
    $items = ParseQueryString($queryValues, $items);

    return $baseURL . '?' . BuildQueryString($items);
}