先用一段代码重现一下问题
乍一看，结果很让人费解：
<?php
$string = <<<EOF
<data>
<foo><bar>hello</bar></foo>
<foo><bar>world</bar></foo>
</data>
EOF;
$data = simplexml_load_string($string);
print_r($data);
print_r($data->foo);
?>
乍一看，结果很让人费解：
SimpleXMLElement Object
(
[foo] => Array
(
[0] => SimpleXMLElement Object
(
[bar] => hello
)
[1] => SimpleXMLElement Object
(
[bar] => world
)
)
)
SimpleXMLElement Object
(
[bar] => hello
)
明明print_r显示foo是一个有两个bar元素的数组，但是最后却仅仅显示了一个bar元素！
原因其实很简单，在如上所示simplexml_load_string的结果里，foo并不是数组，而是一个迭代对象！
可以这样确认：
foreach ($data->foo as $v) print_r($v);
foreach ($data->children() as $v) print_r($v);
看来，print_r或者var_dump之类的表象并不完全可信，自己多留心吧。
假如我们获取的XML数据如下：（可以使用curl、fsockopen等方式获取）
<?xml version="1.0" encoding="UTF-8"?>
<dict num="219" id="219" name="219">
<key>你好</key>
<pos></pos>
<acceptation>Array；Array；Array；</acceptation>
<sent>
<orig>Haven't seen you for a long time. How are you?</orig>
<trans>多日不见了，你好吗？</trans>
</sent>
<sent>
<orig>Hello! How are you?</orig>
<trans>嘿，你好？</trans>
</sent>
<sent>
<orig>Hello, Brooks!How are you?</orig>
<trans>喂，布鲁克斯！你好吗？</trans>
</sent>
<sent>
<orig>Hi, Barbara, how are you?</orig>
<trans>嘿，芭芭拉，你好吗？</trans>
</sent>
<sent>
<orig>How are you? -Quite well, thank you.</orig>
<trans>你好吗？-很好，谢谢你。</trans>
</sent>
</dict>
经过simplexml_load_string得到：
SimpleXMLElement Object
(
[@attributes] => Array
(
[num] => 219
[id] => 219
[name] => 219
)
[key] => 你好
[pos] => SimpleXMLElement Object
(
)
[acceptation] => Array；Array；Array；
[sent] => Array
(
[0] => SimpleXMLElement Object
(
[orig] => Haven't seen you for a long time. How are you?
[trans] => 多日不见了，你好吗？
)
[1] => SimpleXMLElement Object
(
[orig] => Hello! How are you?
[trans] => 嘿，你好？
)
[2] => SimpleXMLElement Object
(
[orig] => Hello, Brooks!How are you?
[trans] => 喂，布鲁克斯！你好吗？
)
[3] => SimpleXMLElement Object
(
[orig] => Hi, Barbara, how are you?
[trans] => 嘿，芭芭拉，你好吗？
)
[4] => SimpleXMLElement Object
(
[orig] => How are you? -Quite well, thank you.
[trans] => 你好吗？-很好，谢谢你。
)
)
)
我们在PHP语言中可以用以下方法取得我们想要的值：
<?php
$data = <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<dict num="219" id="219" name="219">
<key>你好</key>
<pos></pos>
<acceptation>Array；Array；Array；</acceptation>
<sent>
<orig>Haven't seen you for a long time. How are you?</orig>
<trans>多日不见了，你好吗？</trans>
</sent>
<sent>
<orig>Hello! How are you?</orig>
<trans>嘿，你好？</trans>
</sent>
<sent>
<orig>Hello, Brooks!How are you?</orig>
<trans>喂，布鲁克斯！你好吗？</trans>
</sent>
<sent>
<orig>Hi, Barbara, how are you?</orig>
<trans>嘿，芭芭拉，你好吗？</trans>
</sent>
<sent>
<orig>How are you? -Quite well, thank you.</orig>
<trans>你好吗？-很好，谢谢你。</trans>
</sent>
</dict>
XML;
$xmldata = simplexml_load_string($data);
header("Content-Type: text/html; charset=UTF-8");
print_r($xmldata);
echo "<br />".trim($xmldata->sent[0]->orig); //Haven't seen you for a long time. How are you?
echo "<br />".trim($xmldata->key); //你好
?>