如何用PHP制作自己的计数器

<?  
if(!file_exists("visit_log/counter.txt")){  
$fp=fopen("visit_log/counter.txt","w");  
fwrite($fp,"000001"); //这里假设最大为6位，你可以根据需要修改  
$counter="000001";  
fclose($fp);  
} //检查counter.txt文件是否存在，如果不存在则新建一个文件，并且写入“00001”。  
else{  
$fp=fopen("visit_log/counter.txt","r");  
$counter=fread($fp,6);  
//-----------------------------  
$counter+=1;  
//-----------------------------  
fclose($fp);  
switch(strlen($counter)){ //将counter变量格式化，这样显得美观  
case 1:  
$counter="00000".$counter;  
break;  
case 2:  
$counter="0000".$counter;  
break;  
case 3:  
$counter="000".$counter;  
break;  
case 4:  
$counter="00".$counter;  
break;  
case 5:  
$counter="0".$counter;  
break;  
}  
$fp=fopen("visit_log/counter.txt","w");  
fwrite($fp,$counter);  
fclose($fp);  
}  
?>

<?  
$cn=mysql_connect("localhost","root","******");  
mysql_select_db("visit_log",$cn);  
$sql="select * from visit_counter";  
$result=mysql_query($sql,$cn);  
$record=mysql_fetch_array($result);  
if(empty($visited)){  
$counter=$record["amount"]+1;  
$sql="update visit_counter set amount=$counter";  
$result=mysql_query($sql,$cn);  
}  
mysql_close($cn);  
switch(strlen($counter)){ //将counter变量格式化  
case 1:  
$counter="00000".$counter;  
break;  
case 2:  
$counter="0000".$counter;  
break;  
case 3:  
$counter="000".$counter;  
break;  
case 4:  
$counter="00".$counter;  
break;  
case 5:  
$counter="0".$counter;  
break;  
}?>