php怎么读一个多维数据动态的

php如何读一个多维数据动态的、
Array
(
[3] => Array
(
[0] => Array
(
[seconds] => 16930
[no] => 0
[pt] => 3
[k] => 119981343
[size] => 906330
)

)

[2] => Array
(
[0] => Array
(
[seconds] => 16930
[no] => 0
[pt] => 2
[k] => 119980914
[size] => 472101
)

)

[4] => Array
(
[0] => Array
(
[seconds] => 16930
[no] => 0
[pt] => 4
[k] => 119981696
[size] => 1735787
)

)

[99] => Array
(
[0] => Array
(
[seconds] => 16930
[no] => 0
[pt] => 99
[k] => 119981988
[size] => 679868
)

)

)



我如何读到其内的值，就是no pt k size
这是一个动态数据，就是说3,2,4,99不是固定的，因此不能用此法：[4][0][no]
应该怎么办啊？
------解决方案--------------------

foreach($ar as $r) {
  echo $r[0]['k'];
}