我正在编写一个脚本，以输出从PubMed Central API获取的排序信息。我的问题是，我想提取第一作者和第二作者以及第一和第二关键词（就这个问题而言，我们可以只关注一个）。$xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->surname就是一个很好的例子。很明显，我可以把名字打印出来。
我从阅读其他帖子中了解到，我需要一个foreach循环来实现我的愿望。然而，我不明白如何在这种情况下实现这一点。我的代码如下：
<?php
$PMCID = 3545513;
$url = 'http://www.pubmedcentral.nih.gov/oai/oai.cgi?verb=GetRecord&identifier=oai:pubmedcentral.nih.gov:'.$PMCID.'&metadataPrefix=pmc_fm';
$xml = new SimpleXMLElement(file_get_contents($url));
?>
<table>
<tr>
<td>Journal Title</td><td>Year</td><td>Issue</td><td>NOC_Country</td><td>State</td><td>City</td><td>Primary Institution</td><td>Secondary Institution</td><td>First Author</td><td>Second Author</td><td>Topic</td><td>Target Behavior 1</td><td>Target Behavior 2</td><td>Population</td><td>Paper</td><td>Status</td>
</tr>
<tr>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'journal-meta'}->{'journal-title-group'}->{'journal-title'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'pub-date'}->year;?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->issue;?></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->surname;?>, <?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->{'given-names'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->surname;?>, <?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'}->contrib->name->{'given-names'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'title-group'}->{'article-title'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'kwd-group'}->kwd;?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'kwd-group'}->kwd;?></td>
<td></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'article-categories'}->{'subj-group'}->subject;?></td>
<td></td>
</tr>
</table>
如有任何帮助，我们将不胜感激！
最终得到：
<table>
<tr>
<td><strong>Journal Title</strong></td><td><strong>Year</strong></td><td><strong>Issue</strong></td><td><strong>First Author</strong></td><td><strong>Second Author</strong></td><td><strong>Topic</strong></td><td><strong>Target Behavior 1</strong></td><td><strong>Target Behavior 2</strong></td><td><strong>Paper</strong></td>
</tr>
<?php
$PMCID = $_REQUEST['PMCID'];
$url = 'http://www.pubmedcentral.nih.gov/oai/oai.cgi?verb=GetRecord&identifier=oai:pubmedcentral.nih.gov:'.$PMCID.'&metadataPrefix=pmc_fm';
$xml = new SimpleXMLElement(file_get_contents($url));
?>
<tr>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'journal-meta'}->{'journal-title-group'}->{'journal-title'};?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'pub-date'}->year;?></td>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->issue;?></td>
<?php
$n=0;
foreach($xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'contrib-group'} as $author){
echo "<td>" . $author->contrib->name->surname . ", ";
echo $author->contrib->name->{'given-names'} . "</td>";
$n++;
if($n==2) break;
}
unset($n);
unset($author);
?>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'title-group'}->{'article-title'};?></td>
<?php
$i=0;
foreach($xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'kwd-group'}->kwd as $keyword){
echo "<td>" . $keyword . "</td>";
$i++;
if($i==2) break;
}
unset($i);
unset($keyword);
?>
<td><?php echo $xml->GetRecord->record->metadata->article->front->{'article-meta'}->{'article-categories'}->{'subj-group'}->subject;?></td>
</tr>
</table>