$a[one] => 1.
$a[two] => 2.
$a[three] => 3.
$a[seventeen] => 17.
$a = array(
    "one" => 1,
    "two" => 2,
    "three" => 3,
    "seventeen" => 17
);

foreach ($a as $k => $v) {
    echo "\$a[$k] => $v.\n";
}