is_array() returns false on SimpleXml array element

I try to check if SimpleXml element is an array.
I saw the given examples here on PHP doc and so it seems possible to check if a node is an array. But in my case, I cannot do it.

A var_dump($myElement) gives me:

object(SimpleXMLElement)#701 (4) { 
    ["@attributes"]=> array(1) { 
        ["id"]=> string(7) "5831377" 
    } 
    ["openPeriod"]=> string(10) "2016-04-01" 
    ["closePeriod"]=> string(10) "2016-05-31" 
    ["periods"]=> object(SimpleXMLElement)#703 (1) { 
        ["period"]=> array(2) { 
            [0]=> object(SimpleXMLElement)#707 (3) { 
                ["startPeriod"]=> string(8) "10:00:00" 
                ["endPeriod"]=> string(8) "12:30:00" 
                ["weekDays"]=> string(51) "monday,tuesday,wednesday,thursday,friday,saturday,sunday" 
            } 
            [1]=> object(SimpleXMLElement)#702 (3) { 
                ["startPeriod"]=> string(8) "14:00:00" 
                ["endPeriod"]=> string(8) "20:00:00" 
                ["weekDays"]=> string(51) "monday,tuesday,wednesday,thursday,friday,saturday,sunday" 
            } 
        } 
    } 
}

Depending $myElement, $myElement->periods->period could be an object or an array.

But in the given case, debug(is_array($myElement->periods->period)) returns false.

Could you tell me why?

EDIT
Here is the original XML element:

<openingPeriod id="5831487">
    <openPeriod>2016-04-01</openPeriod>
    <closePeriod>2016-05-31</closePeriod>
    <periods>
        <period>
            <startPeriod>10:00:00</startPeriod>
            <endPeriod>12:30:00</endPeriod>
            <weekDays>monday,tuesday,wednesday,thursday,friday,saturday,sunday</weekDays>
        </period>
        <period>
            <startPeriod>14:00:00</startPeriod>
            <endPeriod>20:00:00</endPeriod>
            <weekDays>monday,tuesday,wednesday,thursday,friday,saturday,sunday</weekDays>
        </period>
    </periods>
</openingPeriod>

Solution

Your underlying assumption is wrong:

Depending $myElement, $myElement->periods->period could be an object or an array.

The result of the -> operator on a SimpleXMLElement object is always another SimpleXMLElement object. I'm not sure why there's so many mentions of is_array in the comments of the page you linked to, but I think they're all just making the same mistake. You may be fooled by var_dump or print_r telling you there's an array, but it's lying; that's just how the debug info displays multiple items with the same name.

You can access the object as though it was an array, using [0], foreach, etc, but these are all just convenience features of the object, not an actual array.

If you look at the official examples, you'll see that $myElement->periods->period is just short-hand for $myElement->periods[0]->period. So in most cases, you simply don't need to know if there are multiple children or just one, if you do foreach($myElement->periods->period as $period) for instance, the loop will always work. SimpleXML takes care of the different scenarios for you.

If what you really want to know is how many of a particular element there are, you can use count($myElement->periods->period). But again, you should not need to have any special cases in your code for when there's only one.