用php写个简单的计数器

<?php
        function jsq(){
                $arr = explode("/",$_SERVER["PHP_SELF"]);//获取当前文件的位置信息并以“/”分割存入数组中
                $datfile = $arr[count($arr)-1].".dat";//设置文件位置
                if(!file_exists($datfile)){//如果文件不存在
                        $cf = fopen($datfile,"w");//建立计数器文件
                        fputs($cf,"0");//初始化值为0
                        fclose($cf);//关闭文件
                }else{//文件存在则取回计数器里的数据
                        $cf = fopen($datfile,"r");
                        $counter = trim(fgets($cf,10));//读取10个长度的字符
                        fclose($cf);
                }
                $counter++;//把计数器自增1
                $cf = fopen($datfile,"w");//写入新数据
                fputs($cf,$counter);//将字符$counter写入打开的文件
                fclose($cf);
                return $counter;
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" " http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns=" http://www.w3.org/1999/xhtml">
<head>
<title>web计数器</title>
<meta http-equiv="Content-Type" content="text/html" charset=utf-8 />
</head>
<body>
您是的第<?php echo jsq(); ?>位网友
</body>
</html>