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//模拟一个分类数组$area = array(array('id'=>1,'name'=>'安徽','parent'=>0),array('id'=>2,'name'=>'海淀','parent'=>7),array('id'=>3,'name'=>'濉溪县','parent'=>5),array('id'=>4,'name'=>'昌平','parent'=>7),array('id'=>5,'name'=>'淮北','parent'=>1),array('id'=>6,'name'=>'朝阳','parent'=>7),array('id'=>7,'name'=>'北京','parent'=>0),array('id'=>8,'name'=>'上地','parent'=>2));/** *递归，查找子孙树 */function subtree($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);//string str_repeat ( string $input , int $multiplier )//返回 input 重复 multiplier 次后的结果。foreach($tree as $v) {    echo str_repeat(' |- ',$v['lev']),$v['name'],'
';  //str_repeat — 重复一个字符串}/** *结果 *//*|- 安徽|- |- 淮北|- |- |- 濉溪县|- 北京|- |- 海淀|- |- |- 上地|- |- 昌平|- |- 朝阳*//** *递归，求家谱树 */function familytree($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echo "
";/** *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));