PHP Count A Child of XML Result

I'm trying to count the number of checkin_id's for each customer. Currently im looping through the customers, then using a nested loop to loop through the checkin ids. My thought was to put them in array then use count($checkin_ids). But, what happens is when the $ids array is printed for each customer, it is cumlative containing the checkin_ids from all previous loops. For example, by the end of the loop, the array contains all checkin_ids for all customers. I need a count per customer.

May data looks like this:

<customers>
  <customer>
    <customer_id>7234872934</customer_id>
    <firstname>customer</firstname>
    <middlename/>
    <lastname>name</lastname>
    <dob>1982-10-02</dob>
    <checkins>
        <checkin>
          <checkin_id>89764</checkin_id>
          <checkin_time>11:00</checkin_time>
          <checkin_id>874629</checkin_id>
          <checkin_time>2:00</checkin_time>
        </checkin>
    </checkins>
    <primary_email>customer@email.com</primary_email>
  </customer>

  <customer>
    <customer_id>7234872934</customer_id>
    <firstname>customer</firstname>
    <middlename/>
    <lastname>name</lastname>
    <dob>1982-10-02</dob>
    <checkin>
      <checkin_id>89764</checkin_id>
      <checkin_time>11:00</checkin_time>
      <checkin_id>874629</checkin_id>
      <checkin_time>2:00</checkin_time>
    </checkin>
    <primary_email>customer@email.com</primary_email>
  </customer>

</customers>

My loops

$ids = array();

foreach($customer_result->customers->customer as $customer){
            $email = $customer->primary_email;
            $dob = $customer->dob;
            $firstname = $customer->firstname;
            $lastname = $customer->lastname;

            //Count Number of Checkins
            foreach ($customer->checkins->checkin->checkin_id as $checkin_id) {
                $ids[] = $checkin_id;       
            }

            print_r($ids);
            count($ids);

 }