php中simplexml_load_string使用实例分享

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, *s!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, *s!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, *s!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
?>