多次元配列の問題

Array(    [0] => Array        (            [cat_id] => 141            [cat_name] => 最新公告        )    [1] => Array        (            [cat_id] => 117            [cat_name] => 特别专题相关咨询            [children] => Array                (                    [0] => Array                        (                            [cat_id] => 118                            [cat_name] => 月相盈亏                        )                    [1] => Array                        (                            [cat_id] => 119                            [cat_name] => 陀飞轮                        )                    [2] => Array                        (                            [cat_id] => 120                            [cat_name] => 同轴擒纵                        )                )            )    [2] => Array        (            [cat_id] => 104            [cat_name] => 银行信用卡特惠            [children] => Array                (                    [0] => Array                        (                            [cat_id] => 105                            [cat_name] => 招商银行信用卡相关服务                        )                    [1] => Array                        (                            [cat_id] => 106                            [cat_name] => 民生银行信用卡相关服务                        )                    [2] => Array                        (                            [cat_id] => 107                            [cat_name] => 工商银行信用卡相关服务                        )                    [3] => Array                        (                            [cat_id] => 108                            [cat_name] => 建设银行信用卡相关服务                        )                    [4] => Array                        (                            [cat_id] => 109                            [cat_name] => 交通银行信用卡相关服务                        )                    [5] => Array                        (                            [cat_id] => 110                            [cat_name] => 光大银行信用卡相关服务                        )                    [6] => Array                        (                            [cat_id] => 111                            [cat_name] => 农业银行信用卡相关服务                        )                    [7] => Array                        (                            [cat_id] => 112                            [cat_name] => 中信银行信用卡相关服务                        )                    [8] => Array                        (                            [cat_id] => 113                            [cat_name] => 广发银行信用卡相关服务                        )                    [9] => Array                        (                            [cat_id] => 114                            [cat_name] => 上海银行信用卡相关服务                        )                    [10] => Array                        (                            [cat_id] => 115                            [cat_name] => 华夏银行信用卡相关服务                        )                    [11] => Array                        (                            [cat_id] => 116                            [cat_name] => 浦发银行信用卡相关服务                        )                )        )    [3] => Array        (            [cat_id] => 98            [cat_name] => 短信            [children] => Array                (                    [0] => Array                        (                            [cat_id] => 83                            [cat_name] => 中秋短信                            [children] => Array                                (                                    [0] => Array                                        (                                            [cat_id] => 84                                            [cat_name] => 中秋给恋人短信                                        )                                    [1] => Array                                        (                                            [cat_id] => 85                                            [cat_name] => 中秋给客户短信                                        )                                    [2] => Array                                        (                                            [cat_id] => 86                                            [cat_name] => 中秋给长辈短信                                        )                                    [3] => Array                                        (                                            [cat_id] => 87                                            [cat_name] => 中秋给同事/领导短信                                        )                                )                        )                    [1] => Array                        (                            [cat_id] => 88                            [cat_name] => 圣诞短信                            [children] => Array                                (                                    [0] => Array                                        (                                            [cat_id] => 89                                            [cat_name] => 圣诞给恋人短信                                        )                                    [1] => Array                                        (                                            [cat_id] => 90                                            [cat_name] => 圣诞节祝福短信                                        )                                    [2] => Array                                        (                                            [cat_id] => 91                                            [cat_name] => 圣诞给长辈短信                                        )                                    [3] => Array                                        (                                            [cat_id] => 92                                            [cat_name] => 圣诞节搞笑短信                                        )                                )                        )                )        )     [4] => Array        (            [cat_id] => 141            [cat_name] => 关于我们        ))

echo '<table>';move_bar($ar);echo '</table>';function move_bar($ar, $deep=0) {  foreach($ar as $row) {    echo "<tr class='$deep' id='$row[cat_id]'><td>$row[cat_name]</td></tr>\n";    if(isset($row['children'])) {      move_bar($row['children'], $deep+1);    }  }}