PHP xml_set_default_handler() Function

The PHP xml_set_default_handler() function sets the default handler function for the XML parser.

Syntax

xml_set_default_handler(parser, handler)

Parameters

parser Required. Specify a reference to the XML parser to set up default handler function.

handler

Required. Specify a string containing the name of a function to be used as an event handler. The function must have two parameters:

handler(parser, data)

parser: The first parameter, parser, is a reference to the XML parser calling the handler.
data: The second parameter, data, contains the character data. This may be the XML declaration, document type declaration, entities or other data for which no other handler exists.

Note: Instead of a function name, an array containing an object reference and a method name can also be supplied.

Return Value

Returns true on success or false on failure.

Example: xml_set_default_handler() example

Lets assume that we have a file called test.xml. This file contains following content:

<?xml version="1.0" encoding="UTF-8"?>
<userlist>
  <user>
    <username>John123</username>
    <name>John Smith</name>
    <phone>+1-8054098000</phone>
    <address>Brooklyn, New York, USA</address>
  </user>
</userlist>

In the example below, an XML parser is created using xml_parser_create() function. Then the XML file is opened to parse its data using default handler function char_print. After parsing the document, the parser is freed using xml_parser_free() function.

<?php
//create an XML parser
$parser=xml_parser_create();

//default handler function for XML parser
function char_print($parser, $data) {
  echo $data;
}

//set the default handler function for XML parser
xml_set_default_handler($parser,"char_print");

//opening xml file
$fp = fopen("test.xml", "r");

while($data = fread($fp,4096)) {
  //parsing XML data
  xml_parse($parser,$data,feof($fp)) or

    //displaying error when parse error occurs
    die (sprintf("XML Error: %s at line %d",

    //error string
    xml_error_string(xml_get_error_code($parser)),

    //current line
    xml_get_current_line_number($parser)));
}

//free XML parser
xml_parser_free($parser);

fclose($fp);
?>

The output of the above code will be:

John123 John Smith +1-8054098000
Brooklyn, New York, USA

Example: using default handler function and element handler functions

Consider one more example where the XML document is parsed using default handler function and element handler functions. After parsing the document, the parser is freed using xml_parser_free() function.

<?php
//create an XML parser
$parser=xml_parser_create();

//element handler function named "start_handler"
//enables customized output
function start_handler($parser, $element, $attribs) {     
  switch($element) {
    case "USERNAME":
      echo "<b>User Name : "; 
      break;
    case "NAME":
      echo "Name : ";         
      break;
    case "PHONE":
      echo "Phone : ";        
      break;
    case "ADDRESS":
      echo "Address : ";      
      break;
  }
}
 
//element handler function "end_handler"
function end_handler($parser, $element) {
  if($element == "USERNAME") 
    echo "</b><br>";
  else
    echo "<br>";
}
 
// Setting element handlers
xml_set_element_handler($parser, "start_handler", 
                        "end_handler");

//default handler function for XML parser
function char_print($parser, $data) {
  echo $data;
}

//set the default handler function for XML parser
xml_set_default_handler($parser,"char_print");

//opening xml file
$fp = fopen("test.xml", "r");

while($data = fread($fp,4096)) {
  //parsing XML data
  xml_parse($parser,$data,feof($fp)) or

    //displaying error when parse error occurs
    die (sprintf("XML Error: %s at line %d",

    //error string
    xml_error_string(xml_get_error_code($parser)),

    //current line
    xml_get_current_line_number($parser)));
}

//free XML parser
xml_parser_free($parser);

fclose($fp);
?>

The output of the above code will be:

User Name : John123
Name : John Smith
Phone : +1-8054098000
Address : Brooklyn, New York, USA

❮ PHP XML Parser Reference