PHP SimpleXMLElement registerXPathNamespace()用法及代碼示例

SimpleXMLElement::registerXPathNamespace()函數是PHP中的一個內置函數，用於為XPath查詢創建一個命名空間上下文，該查詢將在SimpleXML對象中接下來執行。

用法:

bool SimpleXMLElement::registerXPathNamespace( $prefix, $namespace )

參數：該函數接受上述和以下描述的兩個參數：

$prefix:它是必填參數。在XPath查詢中，它用於$namespace中給定的名稱空間。
$namespace:：必填參數。它指定XPath查詢的名稱空間。

返回值：成功返回True，失敗返回False。

注意：此函數在PHP 5.2.0和更高版本上可用。

以下示例程序旨在說明PHP中的SimpleXMLElement::registerXPathNamespace()函數：

程序1:

<?php 
  
// Loading XML document to $user 
$user = <<<XML 
<user xmlns:user_id="http://geeksforgeeks.org/user"> 
<single_user id="1"> 
    <user_id:id>12345</user_id:id> 
    <username>Geeks123</username> 
    <name>GeeksforGeeks</name> 
    <phone>+91-XXXXXXXXXX</phone> 
    <detail font-color="blue" font-size="24px"> 
        Noida India 
    </detail> 
</single_user> 
  
<single_user id="2"> 
    <user_id:id>15980</user_id:id> 
    <username>Geeks54321</username> 
    <name>Geeks</name> 
    <phone>+91-XXXXXXXXXX</phone> 
    <detail font-color="blue" font-size="24px"> 
        Noida India 
    </detail> 
</single_user> 
</user> 
XML; 
  
// Loading string as simple xml object 
$xml = simplexml_load_string($user); 
  
// Registering Xpath namespace 
$xml->registerXPathNamespace('u', 'http://geeksforgeeks.org/user'); 
  
// Retrieving xpaths 
$result = $xml->xpath('//u:id'); 
  
// Printing output 
foreach ($result as $id) { 
    echo $id . "<br>"; 
} 
  
?>

輸出：

12345
15980

程序2:

<?php 
  
// Loading XML document to $user 
$user = <<<XML 
<user xmlns:user_id="http://geeksforgeeks.org/user"> 
    <single_user id="1" xmlns:name="http://geeksforgeeks.org/user/name"> 
        <user_id:id>12345</user_id:id> 
        <username>rakesh123</username> 
        <name:firstname>Rakesh</name:firstname> 
        <name:lastname>Kumar</name:lastname> 
        <phone>+91-XXXXXXXXXX</phone> 
        <detail>Noida India</detail> 
    </single_user> 
      
    <single_user id="2" xmlns:name="http://geeksforgeeks.org/user/name"> 
        <user_id:id>57833</user_id:id> 
        <username>man123</username> 
        <name:firstname>Manjeet</name:firstname> 
        <name:lastname>Singh</name:lastname> 
        <phone>+91-XXXXXXXXXX</phone> 
        <detail>Kolkata, India</detail> 
    </single_user> 
      
    <single_user id="3" xmlns:name="http://geeksforgeeks.org/user/name"> 
        <user_id:id>98944</user_id:id> 
        <username>ak98</username> 
        <name:firstname>Ak</name:firstname> 
        <name:lastname>Singh</name:lastname> 
        <phone>+91-XXXXXXXXXX</phone> 
        <detail>Noida India</detail> 
    </single_user> 
</user> 
XML; 
  
// Loading string as simple xml object 
$xml = simplexml_load_string($user); 
  
// Registering xpath namespace 
$xml->registerXPathNamespace('u', 'http://geeksforgeeks.org/user'); 
$xml->registerXPathNamespace('un', 'http://geeksforgeeks.org/user/name'); 
  
// Retrieving xpaths 
$result = $xml->xpath('//u:id'); 
$result_f_name = $xml->xpath('//un:firstname'); 
$result_l_name = $xml->xpath('//un:lastname'); 
  
// Displaying output 
foreach ($result as $id) { 
    echo $id . "<br>"; 
} 
foreach ($result_f_name as $f_name) { 
    echo $f_name . "<br>"; 
} 
foreach ($result_l_name as $l_name) { 
    echo $l_name . "<br>"; 
} 
  
?>

輸出：

12345
57833
98944
Rakesh
Manjeet
Ak
Kumar
Singh
Singh

參考： https://www.php.net/manual/en/simplexmlelement.registerxpathnamespace.php

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