キーと値の関係を維持して、キーでソートする。ksortは昇順、krsortは降順

$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
ksort($fruits);
foreach ($fruits as $key => $val) {
	echo "$key = $val\n";
}

の結果は

a = orange b = banana c = apple d = lemon