PHP date() warning when passing data from SimpleXMLElement

Question

I have a set of XML data like this.

<data>
    <person>
        <name>Alice</name>
        <date>343658755</date>
    </person>
    <person>
        <name>Bob</name>
        <date>655389955</date>
    </person>
    <person>
        <name>Cathy</name>
        <date>741876355</date>
    </person>
</data>

Using PHP I am parsing it with SimpleXMLElement and trying to display the timestamp in a date format.

$data = new SimpleXMLElement($xmlstr);
echo date( 'Y-m-d H:i:s', $data->person[0]->date);

This displays the following warning.

Warning:  date() expects parameter 2 to be long, object given in ....

Echoing $data->person[0]->date displays the timestamp without any problems. var_dump() shows the following output.

object(SimpleXMLElement)#3 (1) {
  [0]=>
  string(9) "343658755"
}

How do I "refer" to this string directly? If this string is inside an object why is there no Error/Warning when I echo it?

The only way I could make it work with the date() function is to convert it to the integer type like this.

echo date( 'Y-m-d H:i:s', (int) $data->person[0]->date );

Does it work with all versions of PHP? Is there anything bad about doing this?

Answer 1

The error message is pretty clear. date() function expects the parameter to be a long, but you're passing a SimpleXML object instead.

As is evident from the var_dump() output $data->person[0]->date is an object. To get just the timestamp part, you'd have to cast it to a string.

This is applicable everywhere. When working SimpleXML, you'd have to explicitly cast the object into a string in order to access the contents inside. For this particular case, the following should work:

echo date('Y-m-d H:i:s', (string) $data->person[0]->date);