成功解析SimpleXMLElement比较'false'返回'true' [英] Successfully parsed SimpleXMLElement comparison to 'false' returning 'true'

问题描述

我有一个非常尴尬的特定问题与simplexml评估。

I got a very awkward and specific issue with a simplexml evaluation.

代码：

$simplexml = simplexml_load_string($xmlstring);
var_dump($simplexml);
var_dump($simplexml == false); //this comparison

var_dump（$ simplexml）返回我的simplexml的实际结构， true'对于这个特定的simplexml，我不能显示结构，因为我的合同。

我相信这是非常具体的问题，因为我尝试其他XML字符串，比较返回'false' 。

var_dump($simplexml) returns the actual structure of my simplexml but the comparison returns 'true' for this specific simplexml, which I can't show the structure because of my contract.
I'm sure that's very specifc issue 'cause I tried other XML strings and the comparison returns 'false'.

$simplexml = simplexml_load_string('<a><b>test</b></a>');
var_dump($simplexml); //returns the actual structure
var_dump($simplexml == false); //returns false

我使用'==='运算符解决了问题，不满意只是让它工作。我想知道为什么'=='运算符返回true。

我读了两个运算符和SimpleXMLElement，在我看来，它应该为这两个运算符返回'false'。
成功解析SimpleXMLElement和布尔值false之间进行比较以返回true的可能原因是什么？

I solved the problem using the '===' operator, but I'm not satisfied with just making it work. I want to understand why the '==' operator returns true.
I read about the two operators and the SimpleXMLElement and on my sight it should return 'false' for both operators. What are the possible reasons for a comparison between a succesfully parsed SimpleXMLElement and the boolean 'false' to return 'true'?

推荐答案

看看这里：
http://www.php.net/manual/en/language.types.boolean.php#language.types.boolean.casting

它表示从空标签创建的SimpleXML对象的值为false。也许这是怎么回事？

It says that SimpleXML objects created from empty tags evaluate to false. Maybe that's what's going on?

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