PHP簡單HTML DOM解析器，在沒有類或id的標記內查找文本

Question

我有一個http://www.statistics.com/index.php?page=glossary&term_id=703

特別是在這些部分中：

<b>Additive Error:</b>
<p> Additive error is the error that is added to the true value and does not 
depend on the true value itself. In other words, the result of the measurement is 
considered as a sum of the true value and the additive error:   </p> 

我盡力使標簽<p>和</p>之間的文本如下：

include('simple_html_dom.php');
$url = 'http://www.statistics.com/index.php?page=glossary&term_id=703';
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$curl_scraped_page = curl_exec($ch);
$html = new simple_html_dom();
$html->load($curl_scraped_page);

foreach ( $html->find('b') as $e ) {
echo $e->innertext . '<br>';
}

它給了我：

Additive Error:
Browse Other Glossary Entries

我試圖將foreach更改為： foreach ( $html->find('b p') as $e ) {

然后foreach ( $html->find('/b p') as $e ) {

然后，它一直給我什么，只有空白頁。 我做錯了什么？ 謝謝。

Answer 1

為什么不使用PHP的內置DOM擴展和xpath？

libxml_use_internal_errors(true);  // <- you might needs this if that page has errors
$dom = new DomDocument();
$dom->loadHtml($curl_scraped_page);
$xpath = new DomXPath($dom);
print $xpath->evaluate('string(//p[preceding::b]/text())');
//                             ^
//  this will get you text content from <p> tags preceded by <b> tags

如果<b>之前有多個<p>標記，而您只想獲得第一個，則將xpath查詢調整為：

string((//p[preceding::b]/text())[1])

要將它們全部作為DOMNodeList ，請省略string()函數： //p[preceding::b]/text() ，然后可以遍歷列表並訪問每個節點的textContent屬性...

Answer 2

如果您希望所有內容都位於b或p標簽內，則可以簡單地執行foreach ($html->find('b,p') as $e) { ... } 。

Answer 3

嘗試這個

<?php
$dom = new DOMDocument();
@$dom->loadHTMLFile('http://www.statistics.com/index.php?page=glossary&term_id=703');
$xpath = new DOMXPath($dom);

$mytext = '';
foreach($xpath->query('//font') as $font){
    $mytext =  $xpath->query('.//p', $font)->item(0)->nodeValue;
    break;
}

echo $mytext;
?>