求解数组序号及所在位置解决思路

求解数组序号及所在位置

$arr = array (<br />  0 => <br />  array (<br />    0 => 'SU14031300617',<br />    'po_num' => 'SU14031300617',<br />  ),<br />  1 => <br />  array (<br />    0 => 'SU14031300623',<br />    'po_num' => 'SU14031300623',<br />  ),<br />  2 => <br />  array (<br />    0 => 'SU14031300626',<br />    'po_num' => 'SU14031300626',<br />  ),<br />  3 => <br />  array (<br />    0 => 'SU14031300627',<br />    'po_num' => 'SU14031300627',<br />  ),<br />  4 => <br />  array (<br />    0 => 'SU14031300616',<br />    'po_num' => 'SU14031300616',<br />  ),<br />  5 => <br />  array (<br />    0 => 'SU14031300618',<br />    'po_num' => 'SU14031300618',<br />  ),<br />  6 => <br />  array (<br />    0 => 'SU14031300622',<br />    'po_num' => 'SU14031300622',<br />  ),<br />  7 => <br />  array (<br />    0 => 'SU14031300624',<br />    'po_num' => 'SU14031300624',<br />  ),<br />  8 => <br />  array (<br />    0 => 'SU14031300625',<br />    'po_num' => 'SU14031300625',<br />  ),<br />)

假设SU14031300617这项，所在数组的位置是8项中的第1项，表示为 1/8，通过序号可求得。请问怎么求解？
------解决方案--------------------

<br />foreach($arr as $k=>$tmp) {<br />    if('SU14031300617' == $tmp[0]) {<br />        return ($k+1) . '/' . count($arr);<br />    }<br />}<br />return false;<br />