Unneded number combination after replacing a number in a string

I get an unneeded number combination.

($_COOKIE):

2, 3, 4, 5, 6, 7, 8, 901234567890123456789, 30

Should be ($_COOKIE):

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12... (till) 30

$_Get['id']="1"; (sorry, forgot to post it.)

Why that happens?

The code:

<?
ob_start(); 
$id=$_GET['id'];
if (!empty($id)){
    $id=str_replace('a9_','', $id);
    $value=$_COOKIE['NaudingasURL'];
    $exp = explode(", ", $value);
    if(in_array($id, $exp)){
        $value2=str_replace(', '.$id,"", ', '.$value);
        $value2=substr($value2, 2, strlen($value2));
        echo'r';
    }
    else{
        $value2=$value.', '开发者_如何学编程.$id; echo'a';
    }
setcookie("NaudingasURL", $value2);
}
ob_end_flush();
?>

I'm calling it with Jquery ajax, but I don't thinks that's the problem.

You are replacing every ",1" with and empty string. So 10 will be 0 and so on...

But i dont understand what exactly you want to achieve?

Ok, if it was what Max said, that you could do it like this:

$exp = explode(", ", $value);
if(in_array($id, $exp)){
    for ($i=0; $i<count($exp); $i++) {
      if ($exp[$i] == $id) {
         unset($exp[$i]);
      }
    }
    $value2 = implode(", ", $exp);
}
else{
    $value2 = implode(", ", $exp).', '.$id;
}