分页
_currentpage = max((int)@$http_get_vars['pageid'], 1);
        $this->_perpage     = 8;
        $this->_itemdata    = array();
foreach ($params as $name => $value) {
            $this->{'_' . $name} = $value;
        }
$this->_totalitems = count($this->_itemdata);
    }
/**
    * returns an array of current pages data
    *
    * @param $pageid desired page id (optional)
    * @return array page data
    */
    function getpagedata($pageid = null)
    {
        if (isset($pageid)) {
            if (!empty($this->_pagedata[$pageid])) {
                return $this->_pagedata[$pageid];
            } else {
                return false;
            }
        }
if (!isset($this->_pagedata)) {
            $this->_generatepagedata();
        }
return $this->getpagedata($this->_currentpage);
    }
/**
    * returns pageid for given offset
    *
    * @param $index offset to get pageid for
    * @return int pageid for given offset
    */
    function getpageidbyoffset($index)
    {
        if (!isset($this->_pagedata)) {
            $this->_generatepagedata();
        }
if (($index % $this->_perpage) > 0) {
            $pageid = ceil((float)$index / (float)$this->_perpage);
        } else {
            $pageid = $index / $this->_perpage;
        }
return $pageid;
    }
/**
    * returns offsets for given pageid. eg, if you
    * pass it pageid one and your perpage limit is 10
    * it will return you 1 and 10. pageid of 2 would
    * give you 11 and 20.
    *
    * @params pageid pageid to get offsets for
    * @return array  first and last offsets
    */
    function getoffsetbypageid($pageid = null)
    {
        $pageid = isset($pageid) ? $pageid : $this->_currentpage;
        if (!isset($this->_pagedata)) {
            $this->_generatepagedata();
        }
if (isset($this->_pagedata[$pageid])) {
            return array(($this->_perpage * ($pageid - 1)) + 1, min($this->_totalitems, $this->_perpage * $pageid));
        } else {
            return array(0,0);
        }
    }
/**
    * returns back/next and page links
    *
    * @param  $back_html html to put inside the back link
    * @param  $next_html html to put inside the next link
    * @return array back/pages/next links
    */
    function getlinks($back_html = '>')
    {
        $url   = $this->_getlinksurl();
        $back  = $this->_getbacklink($url, $back_html);
        $pages = $this->_getpagelinks($url);
        $next  = $this->_getnextlink($url, $next_html);
return array($back, $pages, $next, 'back' => $back, 'pages' => $pages, 'next' => $next);
    }
/**
    * returns number of pages
    *
    * @return int number of pages
    */
    function numpages()
    {
        return $this->_totalpages;
    }
/**
    * returns whether current page is first page
    *
    * @return bool first page or not
    */
    function isfirstpage()
    {
        return ($this->_currentpage == 1);
    }
/**
    * returns whether current page is last page
    *
    * @return bool last page or not
    */
    function islastpage()
    {
        return ($this->_currentpage == $this->_totalpages);
    }
/**
    * returns whether last page is complete
    *
    * @return bool last age complete or not
    */
    function islastpagecomplete()
    {
        return !($this->_totalitems % $this->_perpage);
    }
/**
    * calculates all page data
    */
    function _generatepagedata()
    {
        $this->_totalitems = count($this->_itemdata);
        $this->_totalpages = ceil((float)$this->_totalitems / (float)$this->_perpage);
        $i = 1;
        if (!empty($this->_itemdata)) {
            foreach ($this->_itemdata as $value) {
                $this->_pagedata[$i][] = $value;
                if (count($this->_pagedata[$i]) >= $this->_perpage) {
                    $i++;
                }
            }
        } else {
            $this->_pagedata = array();
        }
    }
/**
    * returns the correct link for the back/pages/next links
    *
    * @return string url
    */
    function _getlinksurl()
    {
        global $http_server_vars;
// sort out query string to prevent messy urls
        $querystring = array();
        if (!empty($http_server_vars['query_string'])) {
            $qs = explode('&', $http_server_vars['query_string']);            
            for ($i = 0, $cnt = count($qs); $i                 list($name, $value) = explode('=', $qs[$i]);
                if ($name != 'pageid') {
                    $qs[$name] = $value;
                }
                unset($qs[$i]);
            }
        }
    if(is_array($qs)){
            foreach ($qs as $name => $value) {
                $querystring[] = $name . '=' . $value;
            }    
    }
        return $http_server_vars['script_name'] . '?' . implode('&', $querystring) . (!empty($querystring) ? '&' : '') . 'pageid=';
    }
/**
    * returns back link
    *
    * @param $url  url to use in the link
    * @param $link html to use as the link
    * @return string the link
    */
    function _getbacklink($url, $link = '    {
        // back link
        if ($this->_currentpage > 1) {
            $back = '_currentpage%20-%201)%20.%20'>' . $link . '';
        } else {
            $back = '';
        }
return $back;
    }
/**
    * returns pages link
    *
    * @param $url  url to use in the link
    * @return string links
    */
    function _getpagelinks($url)
    {
        // create the range
        $params['itemdata'] = range(1, max(1, $this->_totalpages));
        $pager =& new pager($params);
        $links =  $pager->getpagedata($pager->getpageidbyoffset($this->_currentpage));
for ($i=0; $i            if ($links[$i] != $this->_currentpage) {
                $links[$i] = '_getlinksurl()%20.%20%24links%5b%24i%5d%20.%20'>' . $links[$i] . '';
            }
        }
return implode(' ', $links);
    }
/**
    * returns next link
    *
    * @param $url  url to use in the link
    * @param $link html to use as the link
    * @return string the link
    */
    function _getnextlink($url, $link = 'next >>')
    {
        if ($this->_currentpage _totalpages) {
            $next = '_currentpage%20+%201)%20.%20'>' . $link . '';
        } else {
            $next = '';
        }
return $next;
    }
}
?>