<?php

$array = array(

    'fruit1' => 'apple',

    'fruit2' => 'orange',

    'fruit3' => 'grape',

    'fruit4' => 'apple',

    'fruit5' => 'apple');

​

$keys = array_keys($array);     // return array

$values = array_values($array); // return array

?>

$array = array(0 => 100, "cor" => "vermelho");

print_r(array_keys($array));

​

$array = array("azul", "vermelho", "verde", "azul", "azul");

print_r(array_keys($array, "azul"));

​

$array = array("cor"     => array("azul", "vermelho", "verde"),

               "tamanho" => array("pequeno", "medio", "grande"));

print_r(array_keys($array));

​