求:PHP文章分页原理及实用代码?

	/**

	 * 翻页函数

	 *

	 * @param int $num 总纪录数

	 * @param int $perpage 每页大小

	 * @param int $curpage 当前页面

	 * @param string $mpurl url

	 * @return string 类似于: <div class="page">***</div>

	 */

function page($num, $perpage, $curpage, $mpurl) {

		$multipage = '';

		$mpurl .= strpos($mpurl, '?') ? '&' : '?';

		if($num > $perpage) {

			$page = 10;

			$offset = 2;



			$pages = @ceil($num / $perpage);



			if($page > $pages) {

				$from = 1;

				$to = $pages;

			} else {

				$from = $curpage - $offset;

				$to = $from + $page - 1;

				if($from < 1) {

					$to = $curpage + 1 - $from;

					$from = 1;

					if($to - $from < $page) {

						$to = $page;

					}

				} elseif($to > $pages) {

					$from = $pages - $page + 1;

					$to = $pages;

				}

			}



			$multipage = ($curpage - $offset > 1 && $pages > $page ? '<a href="'.$mpurl.'page=1" class="first"'.$ajaxtarget.'>1 ...</a>' : '').

			($curpage > 1 && !$simple ? '<a href="'.$mpurl.'page='.($curpage - 1).'" class="prev"'.$ajaxtarget.'>‹‹</a>' : '');

			for($i = $from; $i <= $to; $i++) {

				$multipage .= $i == $curpage ? '<strong>'.$i.'</strong>' :

				'<a href="'.$mpurl.'page='.$i.($ajaxtarget && $i == $pages && $autogoto ? '#' : '').'"'.$ajaxtarget.'>'.$i.'</a>';

			}



			$multipage .= ($curpage < $pages && !$simple ? '<a href="'.$mpurl.'page='.($curpage + 1).'" class="next"'.$ajaxtarget.'>››</a>' : '').

			($to < $pages ? '<a href="'.$mpurl.'page='.$pages.'" class="last"'.$ajaxtarget.'>... '.$realpages.'</a>' : '').

			(!$simple && $pages > $page && !$ajaxtarget ? '<kbd><input type="text" name="custompage" size="3" onkeydown="if(event.keyCode==13) {window.location=\''.$mpurl.'page=\'+this.value; return false;}" /></kbd>' : '');



			$multipage = $multipage ? '<div class="pages">'.(!$simple ? '<em> '.$num.' </em>' : '').$multipage.'</div>' : '';

		}

		return $multipage;

	}

echo $pagenav;

function page($page_num,$cur_page,$per_group,$base_url){  //分页函数参数列表(有多少页,当前页,每页多少个 ,链接地址)



	$base_url .= strpos($base_url, '?') ? '&' : '?';



	$page_val = "";



	if ($page_num < 1) {

		return $page_val;

	} elseif($page_num == 1) {

		return $page_val = 1;

	}



	$group_ok = !(($page_num-1)%($per_group-1));



	//计算一共有多少组

	if($group_ok) {

		$group_num = ($page_num-1)/($per_group-1);

	} else {

		$group_num = ceil(($page_num-1)/($per_group-1));

	}



	//判断当前页是否为一组的最后一个

	$is_last_page = !(($cur_page-1)%($per_group-1));



	//计算当前在的组数

	if($is_last_page) {

		$cur_group = ($cur_page-1)/($per_group-1) + 1;

	} else {

		$cur_group = ceil(($cur_page-1)/($per_group-1));

	}



	//计算显示的起始页

	$from = ($cur_group - 1) * ($per_group-1) + 1;

	$from = $cur_group <= 1 ? 1 :$from;

	$to = $from + $per_group;

	$to = $to > $page_num ? $page_num + 1 : $to;



	for($a = $from; $a < $to; $a++){

		if( $a != $cur_page) {

			$page_val .= '<a href ='.$base_url.'page='.$a.'>'.$a.'</a>';

		} else {

			$page_val .= $a;

		}

	}



	//上一页下一页首页尾页

	$next=$cur_page+1;

	$prev=$cur_page-1;

	if ($cur_page!=$page_num) {

		$page_val.='<a href ='.$base_url.'page='.$next.'>'.'下一页'.'</a>';

		$page_val .= '<a href ='.$base_url.'page='.$page_num.'>'.'>>'.'</a>'; //尾页

	}

	if ($cur_page!=1) {

		$page_val = '<a href ='.$base_url.'page='.$prev.'>'.'上一页'.'</a>'.$page_val;

		$page_val = '<a href ='.$base_url.'page=1>'.'<<'.'</a>'.$page_val;  //首页

	}



	return $page_val;

}