Per a que funcioni he hagut de donar permisos  d’escriptura des de l’explorador de fitxers de Windows.

[php]

<?php

$myfile = fopen("newfile.txt", "w") or die("Unable to open file!"); //a-> mode append, w->esborra contingut
$txt = "Donald Duck\n"; //primera linia
fwrite($myfile, $txt);
$txt = "Goofy Goof\n"; //segona linia
fwrite($myfile, $txt);
fclose($myfile);

?>

[/php]