PHP counter by file IO

PHP 計數器，使用檔案讀寫的方式實作。

counter.php:

<?php
   $pt = @fopen("log","r");
   if( $pt ){
      $size = filesize("log")==0?1:filesize("log");
      $num = fread($pt,$size);
      fclose($pt);

      if( !is_numeric($num) ){
         $num = 0;
      }
      $num++;

      $pt = fopen("log","w");
      fwrite($pt,$num);
      fclose($pt);
   }else{
      $num=1;
      $pt = fopen("log","w");
      fwrite($pt,$num);
      fclose($pt);
   }
   echo $num." 人次";
?>