A few things to note about SimpleXML_PHP Tutorial

SimpleXML provides a set of simple and fast XML operation methods, which greatly improves the efficiency of XML operations. But sometimes carelessness can cause a lot of trouble. Look at the following piece of code:

$xml = simplexml_load_string();

$title = $xml->title;

echo $title;

$xml->title = test;

echo $title;

Guess what the second output result will be? It is test, not title as imagined. Why is this happening? Here’s why:

echo gettype($xml->title) // object

echo get_class($xml->title); // SimpleXMLElement

See, $xml->title is an instance of the SimpleXMLElement class, not a string. So $title actually holds a reference to the SimpleXMLElement class, not a copy of the string. If you want to get a copy of the string, you can only perform type conversion:

$title = (string)$xml->title; // Get string

$xml->title = test;

echo $title; // Output title

SimpleXMLElement should implement an interface similar to __tostring() (if you are interested, you can take a look at the source code of PHP, in "ext/simplexml/"), so that it can be expressed in expressions such as echo. Similar to a string. So there is another place to pay attention to:

$_SESSION[test] = $xml->title; // Save a SimpleXMLElement variable to SESSION.

$_SESSION[test] = (string)$xml->title; // string

$_SESSION[test] = strval($xml->title); // This works too.

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