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','parent'=>7),

array('id'=>5,'name'=>'淮北','parent'=>1),

array('id'=>6,'name'=>'朝阳','parent'=>7),

array('id'=>7,'name'=>'北京','parent'=>0),

array('id'=>8,'name'=>'上地','parent'=>2)

);

1.递归，查找子孙树

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,'name'=>'安徽','parent'=>0),

            $subs = array_merge($subs,subtree($arr,$v['id'],$lev+1));

        }

    }

    return $subs;

}

$tree = subtree($area,0,1);

foreach($tree as $v) {

    echo str_repeat('&nbsp;&nbsp;',$v['lev']),$v['name'],'<br />';

}

2.递归，求家谱树

家谱树的应用 ,如面包屑导航 首页 > 手机类型 > CDMA手机 > 公益PHP > 递归应用

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

2.迭代，求家谱树

// 迭代,效率比递归高,代码也没多.

// 找家谱树推荐用迭代

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));