Вставка данных в файл XML с помощью PHP DOM

Окончательное решение

sample.XML

    swimming
    running
    Jogging
    Theatre
    Programming

index.php

load("sample.xml", LIBXML_NOBLANKS);

    $activities = $xmldoc->firstChild->firstChild;
    if($activities!=null){
        while($activities!=null){
            echo $activities->textContent."
";
            $activities = $activities->nextSibling;
        }
    }
?>


    insert activity:
    
    

insert.php

load('sample.xml');

    $newAct = $_POST['activity'];

    $root = $xmldoc->firstChild;

    $newElement = $xmldoc->createElement('activity');
    $root->appendChild($newElement);
    $newText = $xmldoc->createTextNode($newAct);
    $newElement->appendChild($newText);

    $xmldoc->save('sample.xml');
?>

php-errors