php - how to give array index a named key on runtime -

here trying use xmlserializer class convert data mysql table xml file.i want xml file this

for ,i need change numeric indexes 'book'.currently can generate array of following form:it has numeric indexing ,but purpose both of indexes (0 , 1) have 'book'.

how can change both numeric indexes 'book'??

full code:

   include('xmlserializer/xml/serializer.php');    $host='localhost';    $user='root';    $pass='';    $db='xmlserializer';     $dbh=new pdo("mysql:host=$host;dbname=$db",$user,$pass);    $sql='select lname,fname employee';    $sth=$dbh->prepare($sql);    $sth->execute();     $xml=array('library'=>array());     $i=0;    while($result=$sth->fetch(pdo::fetch_assoc)){        array_push($xml['library'],$result);     }    print_r($xml);    $serializer=new xml_serializer();      $result=$serializer->serialize($xml);    if($result===true){       file_put_contents('myxml.xml',$serializer->getserializeddata());    } 

you need set default tag in xml_serializer:

so code should be:

$options = array(       "defaulttagname"  => "book", );  $serializer = new xml_serializer($options); 

check link more information : https://pear.php.net/manual/en/package.xml.xml-serializer.xml-serializer.examples.php