array_map() array_map_recursive()
....("strtoupper", $arr)
Array
(
    [0] => aaa
    [1] => bbb
    [2] => ccc
)
Array ( [0] => AAA [1] => BBB [2] => CCC ) Array ( [0] => AAA [1] => BBB [2] => CCC )
....("strtoupper", $arr4)
Array
(
    [0] => kkk
    [1] => Array
        (
            [0] => aaa
            [1] => bbb
            [2] => ccc
        )

)

Array ( [0] => KKK [1] => )
Array ( [0] => KKK [1] => Array ( [0] => AAA [1] => BBB [2] => CCC ) )
function test($a1, $a2) { return $a1.' <-> '.$a2; }
array_map() array_map_recursive()
....("test", $arr, $arr2)
Array
(
    [0] => aaa
    [1] => bbb
    [2] => ccc
)
Array
(
    [d] => ddd
    [e] => eee
    [f] => fff
    [0] => g
)
Array ( [0] => aaa <-> ddd [1] => bbb <-> eee [2] => ccc <-> fff [3] => <-> g ) Array ( [0] => aaa <-> ddd [1] => bbb <-> eee [2] => ccc <-> fff [3] => <-> g )
....("test", $arr3, $arr4)
Array
(
    [1] => hhh
    [2] => iii
    [3] => jjj
    [4] => g
)
Array
(
    [0] => kkk
    [1] => Array
        (
            [0] => aaa
            [1] => bbb
            [2] => ccc
        )

)
Array ( [0] => hhh <-> kkk [1] => iii <-> Array [2] => jjj <-> [3] => g <-> ) Array ( [0] => hhh <-> kkk [1] => Array ( [0] => iii <-> aaa [1] => iii <-> bbb [2] => iii <-> ccc ) [2] => jjj <-> [3] => g <-> )



Array
(
    [0] => 1
    [1] => 8
    [2] => 27
    [3] => Array
        (
            [0] => 64
            [1] => 125
            [2] => 216
        )

)

Array ( [0] => 2 [1] => 4 [2] => 6 [3] => Array ( [0] => 8 [1] => 10 [2] => 12 ) )
Array ( [0] => Array ( [0] => Le nombre 1 se dit uno en Espagnol [1] => Le nombre un se dit uno en Espagnol ) [1] => Array ( [0] => Le nombre 2 se dit dos en Espagnol [1] => Le nombre deux se dit dos en Espagnol ) [2] => Array ( [0] => Le nombre 3 se dit tres en Espagnol [1] => Le nombre trois se dit tres en Espagnol ) )