note:array_filter( )

filter 顧名思義就是篩選器
設定一個過濾的條件
然後將要過濾的array放在array_filter()裡面
array_filter( 要被過濾的array, 過濾條件  );

example:改寫自php手冊，說明連結

<?php
function odd($var)
{
    return ($var%2==1); //奇數
}
function even($var)
{
    return ($var%2==0); //偶數
}

$array1 = array("a"=>1,"b"=>2,"c"=>3,"d"=>4,"e"=>5);
$array2 = array(6,7,8,9,10,11,12);

echo "array1的(odd)奇數有 :\n";
print_r(array_filter($array1,"odd"));

echo "<br/>";

echo "array1的(even)偶數有 :\n";
print_r(array_filter($array1,"even"));
?>

結果 :