PHP | SimpleXMLElement::__construct() Function

Last Updated : 20 May, 2019

Pre-requisite:XML

The __construct() function is an inbuilt function in PHP which is used to create a new SimpleXMLElement object for XML.

Syntax:

SimpleXMLElement::__construct( $data, $options, $data_is_url, $namespace, $is_prefix )

Parameters: This function accepts five parameters as mentioned above and described below:

$data: It is required parameter. It specifies a well-formed XML string or the path or URL to an XML document file if $data_is_url is TRUE.
$options: It is optional parameter. It specifies additional Libxml parameters. Is set by specifying the option and 1 or 0
$data_is_url: It is optional parameter. Its default value is False. If value of this parameter is True, it specifies that the data is a path/URL to a file of XML document instead of string.
$namespace: It is optional parameter. It specifies the namespace URI or prefix.
$is_prefix: It is optional parameter of Boolean type. It specifies True if ns is a prefix and False if ns is a URI. The default value is False.

Return Value: It returns a SimpleXMLElement object that represents the XML structured data

Note: This function is available for PHP 5.0.1 and newer version.

Example

<?php 
  
// Loading XML document to $user 
$user = <<<XML 
<user> 
<username> user123 </username> 
<name> firstname lastname </name> 
<phone> +91-XXXXXXXXXX </phone> 
<detail> I am John Doe. Live in Kolkata, India. </detail> 
</user> 
XML; 
  
// Creating new SimpleXMLElement 
// object from $user 
$xml = new SimpleXMLElement($user); 
  
// Printing as XML 
echo $xml->asXML(); 
  
?> 

Output:

user123 firstname lastname +91-XXXXXXXXXX I am John Doe. Live in Kolkata, India.

Output in browser as source:

Example: Loading XML document from file or url.

sample.xml

<?xml version="1.0"?> 
<user> 
<username> user123 </username> 
<name> firstname lastname </name> 
<phone> +XX-XXXXXXXXXX</phone> 
<detail> I am John Doe. Live in Kolkata, India. </detail> 
</user> 

index.php

<?php 
  
// Loading XML document from sample.xml to $user 
// and creating new SimpleXMLElement object 
$xml = new SimpleXMLElement("sample.xml", 0, TRUE); 
  
// Printing data as xml document 
echo $xml->asXML(); 
  
?> 

Output:

user123 firstname lastname +91-XXXXXXXXXX I am John Doe. Live in Kolkata, India.

Output in browser as source:

Possible values of parameter $option are:

LIBXML_COMPACT – Nodes allocation optimization activated
LIBXML_DTDATTR – This option sets default DTD attributes
LIBXML_DTDLOAD – Load subset externally
LIBXML_DTDVALID – Validate the xml document with the DTD
LIBXML_DOTTED_VERSION – Get libxml version dot seperated
LIBXML_ERR_ERROR – Get errors(recoverable)
LIBXML_ERR_FATAL – Get errors(fatal)
LIBXML_ERR_NONE – Get no errors
LIBXML_ERR_WARNING – Get warnings(simple)
LIBXML_NOBLANKS – Remove all blank nodes in the XML document
LIBXML_NOCDATA – Merge new CDATA as text nodes
LIBXML_NOEMPTYTAG – Expand empty tags
LIBXML_NOENT – Substitute entities in XML document
LIBXML_NOERROR – restrict error report
LIBXML_NONET – Disables network access while loading the XML documents
LIBXML_NOWARNING – restricts warning reports
LIBXML_NOXMLDECL – Drops the XML declaration when saving the document
LIBXML_NSCLEAN – Removes all redundant namespace declarations
LIBXML_PARSEHUGE – Sets XML_PARSE_HUGE flag, which remove any hardcoded limit from the parser which again affects limits like the size of text nodes and maximum depth of a document
LIBXML_XINCLUDE – Substitution of implements XInclude
LIBXML_VERSION – Get LIBXML version in integer format

Reference: https://www.php.net/manual/en/simplexmlelement.construct.php

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