PHP URL https 和 http 转换

/**
     * 修改 https 和 http
     * @param $url $url 域名
     * @param int $type 0 返回https 1 返回 http
     * @return string
     */
    function set_http_type($url, $type = 0)
    {
        $domainTop = substr($url, 0, 5);
        if ($type) {
            if ($domainTop == 'https') $url = 'http' . substr($url, 5, strlen($url));
        } else {
            if ($domainTop != 'https') $url = 'https:' . substr($url, 5, strlen($url));
        }
        return $url;
    }