javascript - How to write a recursive function using levels depth? -

my function:

 public static function f($rows)        {            $str = '<ul>';            $level = 1;            foreach($rows $row)            {                if($row['section_level'] > $level)                {                    $level = $row['section_level'];                    // here want call function again recursion, how??                }                else                {                    $str .= '<li><a href="#">'.$row['username'].'</a></li>';                }            }            $str .= '</ul>';            return $str;        } 

my array:

array (     array(       ['name'] => 'test1',      ['level'] => 1     },    array(       ['name'] => 'test2',      ['level'] => 2     },     array(       ['name'] => 'test3',      ['level'] => 2     },    array(       ['name'] => 'test4',      ['level'] => 3     },    array(       ['name'] => 'test5',      ['level'] => 3     },    array(       ['name'] => 'test6',      ['level'] => 3     },    array(       ['name'] => 'test7',      ['level'] => 3     },    ) 

can please me complete function render array levels, adding each level <ul>, this:

<ul>   <li>   <a href="#">level1</a>     <ul>       <li><a href="#">level2</a></li>       <li><a href="#">level2</a></li>       <li><a href="#">level2</a></li>       <li><a href="#">level2</a></li>     </ul>   </li>   <li>   <a href="#">level1</a>     <ul>       <li><a href="#">level2</a></li>       <li><a href="#">level2</a></li>       <li><a href="#">level2</a></li>       <li><a href="#">level2</a></li>     </ul>   </li> </ul> 

the idea recursion build data structure tree.

therefore, depth not important, parent - child relationship essential.

that means in array, need @ least have 2 value in 1 array element, example:

[ 'id' => 1, 'parent' => null ], [ 'id' => 2, 'parent' => 1 ], [ 'id' => 3, 'parent' => 1 ], [ 'id' => 4, 'parent' => 2 ], .... 

once have data array, can use http://hezachary.wordpress.com/2008/07/19/%e6%95%b0%e7%bb%84%e5%ad%90%e7%88%b6%e7%ba%a7%e9%80%92%e5%bd%92%ef%bc%8c%e6%a0%91%e7%8a%b6%e7%bb%93%e6%9e%84%e7%94%9f%e6%88%90/ run array, , structured array.

then can use function recursion export html, such as:

function display( $ary ){     echo '<ul>';     foreach($ary $data){         echo '<li>';         echo $data['html'];         if( sizeof( $data['node'] ) ){             display( $ary );         }         echo '</li>';     }     echo '</ul>'; } 

here solution nest strucutre, not @ all:

function f($rows) {     $str = '';     $level = 0;     $first_li_mode = true;     foreach ($rows $row) {         if ($level > $row['level']) {             $str .= '</li></ul>' . "\n";             $str .= '</li><li><a href="#">' . $row['name'] . '</a>' . "\n";             $first_li_mode = true;         } elseif ($row['level'] > $level) {             $str .= '<ul><li><a href="#">' . $row['name'] . '</a>' . "\n";             $first_li_mode = false;             ;         } else {             if (!$first_li_mode) {                 $str .= '</li>' . "\n";             } else {                 $first_li_mode = false;             }             $str .= '<li><a href="#">' . $row['name'] . '</a>' . "\n";         }          $level = $row['level'];     }     while ($level > 0) {         $str .= '</li></ul>' . "\n";         $level--;     }     return $str; }   $qrr = array(     array('name' => 'test1', 'level' => 1),     array('name' => 'test2', 'level' => 2),     array('name' => 'test3', 'level' => 2),     array('name' => 'test4', 'level' => 3),     array('name' => 'test5', 'level' => 3),     array('name' => 'test6', 'level' => 3),     array('name' => 'test7', 'level' => 3),     array('name' => 'test8', 'level' => 2),     array('name' => 'test9', 'level' => 1), );  echo f($qrr);