小PHP数组面试题

$a = array("1"=>"A",1=>"B","C",2=>"D");
print_r($a);
echo "<br/>";
echo count($a);
echo "<br/>";
$a = array(1,2,4,8);
$b = array(0,2,4,6,8,10);
print_r(
    array_merge(
            array_diff($a, $b),
            array_diff($b, $a)
        )   
    );

$a = array("1"=>"A",1=>"B","C",2=>"D");
print_r