简单的网站访问量计数器实现 php

<meta charset="UTF-8">
<title>浏览计数器</title>

<?php
    //数字输出网页计数器
    $max_len = 9;
    $CounterFile = "counter.dat";
    if(!file_exists($CounterFile)){        //如果计数器文件不存在
        $counter = 0;                    
        $cf = fopen($CounterFile,"w");    //打开文件
        fputs($cf,'0');                    //初始化计数器
        fclose($cf);                    //关闭文件
    }
    else{                                        //取回当前计数器的值
        $cf = fopen($CounterFile,"r");
        $counter = trim(fgets($cf,$max_len));
        fclose($cf);
    }
    $counter++;                                    //计数器加一
    $cf = fopen($CounterFile,"w");                //写入新的数据
    fputs($cf,$counter);
    fclose($cf);
?>
<div id="dd" align="center">
    <span>欢迎您!</span>
    <span>您是本站的第
        <?php
         echo $counter;                            //输出计数器
        ?>
    位访客！</span>
</div>