PHP SimpleXMLElement 对象

今天在用RedbeanPHP 写数据库接口的时候,发现从SimpleXMLElement对象里面出来的值,按理说都是string, 怎么也不能赋值给RedbeanPHP, 用var_dump看了一下,发现SimpleXMLElement对象比较有意思,里面嵌套的对象以及property 的type 都是object,而且都是SimpleXMLElement 对象,在google上搜了一下发现问这个问题的不少。

https://stackoverflow.com/questions/416548/forcing-a-simplexml-object-to-a-string-regardless-of-context

比如说XML是这样的:

<channel>
<item>
<title>This is title 1</title>
</item>
</channel>

下面这样确实能够输出string:

$xml = simplexml_load_string($xmlstring);
echo $xml->channel->item->title;

但是除了echo 以外,下面这样就不能被当成string了

$foo = array( $xml->channel->item->title );

这是因为$XML->channel->item->title 的type 其实仍然为SimpleXMLElement的对象

我们可以用typecast来解决这个问题:

$foo = array( (string) $xml->channel->item->title );

The above code internally calls __toString() on the SimpleXMLObject. This method is not publicly available, as it interferes with the mapping scheme of the SimpleXMLObject, but it can still be invoked in the above manner.

另外看到有人这么写也可以:

$foo = array( $xml->channel->item->title.'' );

通过gettype查看确实变成了string,具体原理不知道

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