php获取数组的键值

<?phpheader ( "Content-type: text/html; charset=utf-8" );    $info["aa"]=1;    $info["bb"]=2;    $info["cc"]=3;    $info["dd"]="abcd";        foreach($info as $k=>$val)    {        echo "键：".$k."  值：".$val;        echo "<br>";    }?>