php实现无限级分类

$area = array(
array('id'=>1,'name'=>'安徽','parent'=>0),
array('id'=>2,'name'=>'海淀','parent'=>7),
array('id'=>3,'name'=>'濉溪县','parent'=>5),
array('id'=>4,'name'=>'昌平',
array('id'=>5,'name'=>'淮北','parent'=>1),
array('id'=>6,'name'=>'朝阳',
array('id'=>7,'name'=>'北京',
array('id'=>8,'name'=>'上地','parent'=>2)
);

function subtree($arr,$id=0,$lev=1) {
??? $subs = array(); // 子孙数组
??? foreach($arr as $v) {
??????? if($v['parent'] == $id) {
??????????? $v['lev'] = $lev;
??????????? $subs[] = $v; // 举例说找到array('id'=>1,
??????????? $subs = array_merge($subs,subtree($arr,$v['id'],$lev+1));
??????? }
??? }
??? return $subs;
}
$tree = subtree($area,1);
foreach($tree as $v) {
??? echo str_repeat('??',$v['lev']),$v['name'],'<br />';
}

function familytree($arr,$id) {
??? $tree = array();
??? foreach($arr as $v) {
??????? if($v['id'] == $id) {// 判断要不要找父栏目
??????????? if($v['parent'] > 0) { // parnet>0,说明有父栏目
??????????????? $tree = array_merge($tree,familytree($arr,$v['parent']));
??????????? }
??????????? $tree[] = $v; // 以找到上地为例
??????? }
??? }
??? return $tree;
}
print_r(familytree($area,8)); // 北京->海淀->上地

// 迭代,效率比递归高,代码也没多.
// 找家谱树保举用迭代
function tree($arr,$id) {
??? $tree = array();
??? while($id !== 0) {
??????? foreach($arr as $v) {
??????????? if($v['id'] == $id) {
??????????????? $tree[] = $v;
??????????????? $id = $v['parent'];
??????????????? break;
??????????? }???
??????? }
??? }
??? return $tree;
}
print_r(tree($area,8));