Convert a PHP array into XML file using SimpleXML

gistfile1.php

class ArrayToXML
{
    /**
     * The main function for converting to an XML document.
     * Pass in a multi dimensional array and this recrusively loops through and builds up an XML document.
     * Based on: http://snipplr.com/view/3491/convert-php-array-to-xml-or-simple-xml-object-if-you-wish/
	 * 
     * @param array $data
     * @param string $rootNodeName - what you want the root node to be - defaultsto data.
     * @param SimpleXMLElement $xml - should only be used recursively
     * @return string XML
     */
    public static function toXml($data, $rootNodeName = 'data', &$xml=null)
    {
        // turn off compatibility mode as simple xml throws a wobbly if you don't.
    if ( ini_get('zend.ze1_compatibility_mode') == 1 ) ini_set ( 'zend.ze1_compatibility_mode', 0 );
    if ( is_null( $xml ) ) {
    	 $xml = simplexml_load_string(stripslashes("<?xml version='1.0' encoding='utf-8'?><root xmlns:example='http://example.namespace.com' version='1.0'></root>"));
	}

    // loop through the data passed in.
    foreach( $data as $key => $value ) {

        // no numeric keys in our xml please!
        $numeric = false;
        if ( is_numeric( $key ) ) {
            $numeric = 1;
            $key = $rootNodeName;
        }

        // delete any char not allowed in XML element names
        $key = preg_replace('/[^a-z0-9\-\_\.\:]/i', '', $key);
		
		//check to see if there should be an attribute added (expecting to see _id_)
		$attrs = false;

		//if there are attributes in the array (denoted by attr_**) then add as XML attributes
		if ( is_array( $value ) ) {
			foreach($value as $i => $v ) {
				$attr_start = false;
				$attr_start = stripos($i, 'attr_');
				if ($attr_start === 0) {
					$attrs[substr($i, 5)] = $v; unset($value[$i]);
				}
			}
		}
		  
		
        // if there is another array found recursively call this function
        if ( is_array( $value ) ) {

            if ( ArrayToXML::is_assoc( $value ) || $numeric ) {

                // older SimpleXMLElement Libraries do not have the addChild Method
                if (method_exists('SimpleXMLElement','addChild'))
                {
                    $node = $xml->addChild( $key, null, 'http://www.lcc.arts.ac.uk/' );
					if ($attrs) {
						foreach($attrs as $key => $attribute) {
							$node->addAttribute($key, $attribute);
						}
					}
                }

            }else{
                $node =$xml;
            }

            // recrusive call.
            if ( $numeric ) $key = 'anon';
            ArrayToXML::toXml( $value, $key, $node );
        } else {

                // older SimplXMLElement Libraries do not have the addChild Method
                if (method_exists('SimpleXMLElement','addChild'))
                {
                    $childnode = $xml->addChild( $key, $value, 'http://www.lcc.arts.ac.uk/' );
					if ($attrs) {
						foreach($attrs as $key => $attribute) {
							$childnode->addAttribute($key, $attribute);
						}
					}
                }
        }
    }

	// pass back as unformatted XML
	//return $xml->asXML('data.xml');

	// if you want the XML to be formatted, use the below instead to return the XML
	    $doc = new DOMDocument('1.0');
	    $doc->preserveWhiteSpace = false;
	    @$doc->loadXML( ArrayToXML::fixCDATA($xml->asXML()) );
	    $doc->formatOutput = true;
	    //return $doc->saveXML();
	    return $doc->save('data.xml');
	}

	public static function fixCDATA($string) {
		//fix CDATA tags
		$find[]     = '&lt;![CDATA[';
		$replace[] = '<![CDATA[';
		$find[]     = ']]&gt;';
		$replace[] = ']]>';	
		
		$string = str_ireplace($find, $replace, $string);	
		return $string;
	}

/**
 * Convert an XML document to a multi dimensional array
 * Pass in an XML document (or SimpleXMLElement object) and this recrusively loops through and builds a representative array
 *
 * @param string $xml - XML document - can optionally be a SimpleXMLElement object
 * @return array ARRAY
 */
	public static function toArray( $xml ) {
	    if ( is_string( $xml ) ) $xml = new SimpleXMLElement( $xml );
	    $children = $xml->children();
	    if ( !$children ) return (string) $xml;
	    $arr = array();
	    foreach ( $children as $key => $node ) {
	        $node = ArrayToXML::toArray( $node );
	
	        // support for 'anon' non-associative arrays
	        if ( $key == 'anon' ) $key = count( $arr );
	
	        // if the node is already set, put it into an array
	        if ( isset( $arr[$key] ) ) {
	            if ( !is_array( $arr[$key] ) || $arr[$key][0] == null ) $arr[$key] = array( $arr[$key] );
	            $arr[$key][] = $node;
	        } else {
	            $arr[$key] = $node;
	        }
	    }
	    return $arr;
	}
	
	// determine if a variable is an associative array
	public static function is_assoc( $array ) {
	    return (is_array($array) && 0 !== count(array_diff_key($array, array_keys(array_keys($array)))));
	}
}

Yayyyy, thanks! This perfectly working. return $doc->saveXML();

it would be useful if we have this piece of code esp for node with empty value :
on Line number:48

  if(empty($value)){
      $xml->addChild ($key,'');
    }