写入xml文件时格式化

  $doc = new DOMDocument(); 
  $doc->load(\'xml/lead.xml\');
  $doc->formatOutput = true; 


  $tags = $doc->getElementsByTagName(\'RootElement\');
  $r = $tags->item(0);

   $a = $doc->createElement( \'Lead\' );
   $r->appendChild( $a );

   $b = $doc->createElement( \'Contact\' ); 
  $b->setAttribute(\'FirstName\', \'\'.$name.\'\');
  $b->setAttribute(\'LastName\', \'\'.$last_name.\'\');
  $b->setAttribute(\'Email\', \'\'.$email.\'\');
  $b->setAttribute(\'StreetAddress\', \'\'.$address.\'\');
  $b->setAttribute(\'City\', \'\'.$city.\'\');

  $a->appendChild( $b ); 

  $c = $doc->createElement( \'Qualifications\' );

  $a->appendChild( $c );

  $d = $doc->createElement( \'PropertyInterest\' );
  $d->setAttribute(\"BuilderName\",\"Test\");

  $a->appendChild( $d ); 

<RootElement>






<Lead><Contact FirstName=\"test \" LastName=\"test\" Email=\"testk@gmail.com\" StreetAddress=\"n/a\" City=\"test\"/><Qualifications/><PropertyInterest BuilderName=\"test\"/></Lead></RootElement>