XML Parser
All modern browsers have built-in XML parsers.
The XML parser converts the XML document into an XML DOM object - an object that can be manipulated through JavaScript
<?xml version="1.0" encoding="ISO-8859-1"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
Next we write a php file to operate the above code
<?php
//Initialize the XML parser
$parser=xml_parser_create();
//Function to use at the start of an element
function start($parser,$element_name,$element_attrs){
switch($element_name){
case "NOTE":
echo "-- Note --<br>";break;
case "TO":
echo "To: ";break;
case "FROM":
echo "From: ";break;
case "HEADING":
echo "Heading: ";break;
case "BODY":
echo "Message: ";
}
}
//Function to use at the end of an element
function stop($parser,$element_name){
echo "<br>";
}
//Function to use when finding character data
function char($parser,$data){
echo $data;
}
//Specify element handler
xml_set_element_handler($parser,"start","stop");
//Specify data handler
xml_set_character_data_handler($parser,"char");
//Open XML file
$fp=fopen("test.xml","r");
//Read data
while ($data=fread($fp,4096)){
xml_parse($parser,$data,feof($fp)) or
die (sprintf("XML Error: %s at line %d",
xml_error_string(xml_get_error_code($parser)),
xml_get_current_line_number($parser)));
}
//Free the XML parser
xml_parser_free($parser);
?>Working principle:
Initialize the XML parser through the xml_parser_create() function
Create functions that match different event handlers
Add xml_set_element_handler( ) function to define which function is executed when the parser encounters the start and end tags
Add the xml_set_character_data_handler() function to define which function is executed when the parser encounters character data
Pass xml_parse() function to parse the file "test.xml"
In case there is an error, add the xml_error_string() function to convert the XML error into a text description
Call the xml_parser_free() function to release the allocation Memory given to xml_parser_create() function
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