<? start_session();


$sayilar= array('ali','veli','kirk','dokuz','elli'); 
$kelime_sayisi = count($sayilar);
$eksi_bir = $kelime_sayisi - 1;

if(!isset($_SESSION['numara'])){

$_SESSION['numara'] = 0;

echo $sayilar[$_SESSION[numara]];
}
else if ($_SESSION['numara'] != $eksi_bir) {
//eger bu durumda 4 e esit degil ise 

$_SESSION['numara'] = $_SESSION['numara'] +1 ;


echo  $sayilar[$_SESSION[numara]];



}
else {
// 4 e kadar yukarida gosterildi eger $_SESSION['numara'] = 5 ise
// arraydeki sayidan yukari cikmamak icin yani 0 inci key i gostermek icin

$_SESSION['numara'] = 0;
echo $sayilar[$_SESSION[numara]];
}