PHP实现无限级分类（不使用递归）

<?php $list = array( array('id'=>1, 'fid'=>0, 'title' => '中国'),  array('id'=>2, 'fid'=>1, 'title' => '江苏'), array('id'=>3, 'fid'=>1, 'title' => '安徽'), array('id'=>4, 'fid'=>8, 'title' => '江阴'), array('id'=>5, 'fid'=>3, 'title' => '芜湖'), array('id'=>6, 'fid'=>3, 'title' => '合肥'), array('id'=>7, 'fid'=>3, 'title' => '蚌埠'), array('id'=>8, 'fid'=>8, 'title' => '无锡') );?>

<ul> <li class="first-child"> <div>江苏</div> <ul> <li class="first-child last-child"> <div>无锡</div> <ul> <li class="first-child last-child"> <div>江阴</div> </li> </ul> </li> </ul> </li> <li class="last-child"> <div>安徽</div> <ul> <li class="first-child"><div>芜湖</div></li> <li><div>合肥</div></li> <li class="last-child"><div>蚌埠</div></li> </ul> </li></ul>

<ul><?php echo get_tree_ul($list, 1); ?></ul>

<select> <option value="2">江苏</option> <option value="8">    无锡</option> <option value="4">        江阴</option> <option value="3">安徽</option> <option value="5">    芜湖</option> <option value="6">    合肥</option> <option value="7">    蚌埠</option></select>

<select><?php // get_tree_option()返回数组，并为每个元素增加了“深度”（即depth）列，直接输出即可 $options = get_tree_option($list, 1);  foreach($options as $op) { echo '<option value="' . $op['id'] .'">' . str_repeat(" ", $op['depth'] * 4) . $op['title'] . '<;/option>'; }?><;/select>

<?php $children = get_tree_child($list, 0); echo implode(',', $children); // 输出：1,3,2,7,6,5,8,4?>

<?php $children = get_tree_parent($list, 4); echo implode(',', $children); //8, 2, 10?>

<?phpfunction get_tree_child($data, $fid) { $result = array(); $fids = array($fid); do { $cids = array(); $flag = false; foreach($fids as $fid) { for($i = count($data) - 1; $i >=0 ; $i--) { $node = $data[$i]; if($node['fid'] == $fid) { array_splice($data, $i , 1); $result[] = $node['id']; $cids[] = $node['id']; $flag = true; } } } $fids = $cids; } while($flag === true); return $result;}function get_tree_parent($data, $id) { $result = array(); $obj = array(); foreach($data as $node) { $obj[$node['id']] = $node; }  $value = isset($obj[$id]) ? $obj[$id] : null;  while($value) { $id = null; foreach($data as $node) { if($node['id'] == $value['fid']) { $id = $node['id']; $result[] = $node['id']; break; } } if($id === null) { $result[] = $value['fid']; } $value = isset($obj[$id]) ? $obj[$id] : null; } unset($obj); return $result;}function get_tree_ul($data, $fid) { $stack = array($fid); $child = array(); $added_left = array(); $added_right= array(); $html_left = array(); $html_right = array(); $obj = array(); $loop = 0; foreach($data as $node) { $pid = $node['fid']; if(!isset($child[$pid])) { $child[$pid] = array(); } array_push($child[$pid], $node['id']); $obj[$node['id']] = $node; } while (count($stack) > 0) {  $id = $stack[0]; $flag = false; $node = isset($obj[$id]) ? $obj[$id] : null; if (isset($child[$id])) { $cids = $child[$id]; $length = count($cids); for($i = $length - 1; $i >= 0; $i--) { array_unshift($stack, $cids[$i]); } $obj[$cids[$length - 1]]['isLastChild'] = true; $obj[$cids[0]]['isFirstChild'] = true; $flag = true; } if ($id != $fid && $node && !isset($added_left[$id])) { if(isset($node['isFirstChild']) && isset($node['isLastChild'])) { $html_left[] = '<li class="first-child last-child">'; } else if(isset($node['isFirstChild'])) { $html_left[] = '<li class="first-child">'; } else if(isset($node['isLastChild'])) { $html_left[] = '<li class="last-child">'; } else { $html_left[] = '<li>'; }  $html_left[] = ($flag === true) ? "<div>{$node['title']}</div><ul>" : "<div>{$node['title']}</div>"; $added_left[$id] = true; }  if ($id != $fid && $node && !isset($added_right[$id])) { $html_right[] = ($flag === true) ? '</ul></li>' : '</li>'; $added_right[$id] = true; } if ($flag == false) { if($node) { $cids = $child[$node['fid']]; for ($i = count($cids) - 1; $i >= 0; $i--) { if ($cids[$i] == $id) { array_splice($child[$node['fid']], $i, 1); break; } }  if(count($child[$node['fid']]) == 0) { $child[$node['fid']] = null; } } array_push($html_left, array_pop($html_right)); array_shift($stack); } $loop++; if($loop > 5000) return $html_left; } unset($child); unset($obj); return implode('', $html_left);}function get_tree_option($data, $fid) { $stack = array($fid); $child = array(); $added = array(); $options = array(); $obj = array(); $loop = 0; $depth = -1; foreach($data as $node) { $pid = $node['fid']; if(!isset($child[$pid])) { $child[$pid] = array(); } array_push($child[$pid], $node['id']); $obj[$node['id']] = $node; } while (count($stack) > 0) {  $id = $stack[0]; $flag = false; $node = isset($obj[$id]) ? $obj[$id] : null; if (isset($child[$id])) { for($i = count($child[$id]) - 1; $i >= 0; $i--) { array_unshift($stack, $child[$id][$i]); } $flag = true; } if ($id != $fid && $node && !isset($added[$id])) { $node['depth'] = $depth; $options[] = $node; $added[$id] = true; } if($flag == true){ $depth++; } else { if($node) { for ($i = count($child[$node['fid']]) - 1; $i >= 0; $i--) { if ($child[$node['fid']][$i] == $id) { array_splice($child[$node['fid']], $i, 1); break; } }  if(count($child[$node['fid']]) == 0) { $child[$node['fid']] = null; $depth--; } } array_shift($stack); } $loop++; if($loop > 5000) return $options; } unset($child); unset($obj); return $options;}?>