list()和each()有关问题

$fruit = array('a' =>'apple','b'=>'banana','c'=>'cranberry' );
reset($fruit);
while (list($key,$val)=each($fruit))
{
	echo "$key=>$val
";
}
//------------------------------------------------------------------------


each()不是由4个元素构成么
比如第一个是 Array ( [1] => apple [value] => apple [0] => a [key] => a )
看手册说list()是从最右边参数开始赋值的  
each()4个元素究竟怎么赋值给list两个元素  按理说不是把前两个apple赋值给$key和$val了吗? 
为啥最后echo能正常

$fruit = array('a' =>'apple');
print_r(each($fruit));

Array
(
    [1] => apple
    [value] => apple
    [0] => a
    [key] => a
)

reset($fruit);
list($key, $value) = each($fruit);
echo "$key => $value";

a => apple

$ar = array('a', 'b', 'c' => 'c');
list($a, $b, $c) = $ar; //会有 Undefined offset: 2 警告
echo "$a $b $c\n";

$ar = array(1 => 'a', 2 => 'b', 0 => 'c');
list($a, $b, $c) = $ar;
echo "$a $b $c\n";

c a b

$ar = array('a', 'b', 'c');
list($aa[$b][$c], $b, $c) = $ar;
print_r($aa);

Array
(
    [b] => Array
        (
            [c] => a
        )

)