You forgot the unset() in there bro.

function buildTree(array &$elements, $parentId = 0) {
    $branch = array();

    foreach ($elements as $element) {
        if ($element[ parent_id ] == $parentId) {
            $children = buildTree($elements, $element[ id ]);
            if ($children) {
                $element[ children ] = $children;
            }
            $branch[$element[ id ]] = $element;
            unset($elements[$element[ id ]]);
        }
    }
    return $branch;
}

然而,正如 m夫指出的,ImmortalFirefly的解决办法并不挽救没有子女的父母。 I ve edited the function tofix this issue:

function buildTree(array &$elements, $parentId = 0) {

    $branch = array();

    foreach ($elements as &$element) {

        if ($element[ parent_id ] == $parentId) {
            $children = buildTree($elements, $element[ id ]);
            if ($children) {
                $element[ children ] = $children;
            }
            $branch[$element[ id ]] = $element;
            unset($element);
        }
    }
    return $branch;
}

对我来说,这项工作是:

$index=array();
$tree=array();
foreach ($ori as $key=>$var) {
  $var=array_shift($ori);
  if ($var[ id ]==0) $var[ id ]=$key;
  if ((string)$var[ parent_id ]=== 0 ) {
    $tree[$key]=$var;
    $index[$key]=&$tree[$key];
  } else if (isset($index[$var[ parent_id ]])) {
    if (!isset($index[$var[ parent_id ]][ children ])) $index[$var[ parent_id ]][ children ]=array();
    $index[$var[ parent_id ]][ children ][$key]=$var;
    $index[$key]=&$index[$var[ parent_id ]][ children ][$key];
  } else {
    array_push($ori,$var);
  }
}
unset($index);
print_r($tree);

我可以看到逻辑,但结果是:

Array
(
    [0] => Array
        (
            [id] => 0
            [parent_id] => 0
        )

    [1] => Array
        (
            [id] => 1
            [parent_id] => 0
        )

IMHO, is parent_id = o, shouldn t *** be a child of [0] here?

Anyway, references to the rescue:

$tree = array();
foreach($inputarray as $item){
     if(!isset($tree[$item[ id ]])) $tree[$item[ id ]] = array();
     $tree[$item[ id ]] = array_merge($tree[$item[ id ]],$item);
     if(!isset($tree[$item[ parent_id ]])) $tree[$item[ parent_id ]] = array();
     if(!isset($tree[$item[ parent_id ]][ children ])) $tree[$item[ parent_id ]][ children ] = array();
     $tree[$item[ parent_id ]][ children ][] = &$tree[$item[ id ]];
}
$result = $tree[0][ children ];
unset($tree);
print_r($result);

Because you have abused 0 as both a magic number as root, and an existing id, we now have recursion in the id=0 branch. Adding if($item[ parent_id ]!=$item[ id ]) before $tree[$item[ parent_id ]][ children ][] = &$tree[$item[ id ]]; could prevent that, but it isn t pretty.

可能建造来源阵列,但你可以使用这一功能(表面上——id,id, 标题):

$q = mysql_query("SELECT id, parent_id, name FROM categories");
while ($r = mysql_fetch_row($q)) {
  $names[$r[0]] = $r[2];
  $children[$r[0]][] = $r[1];
 }

function render_select($root=0, $level=-1) {
  global $names, $children;
  if ($root != 0)
    echo  <option>  . strrep(   , $level) . $names[$root] .  </option> ;
  foreach ($children[$root] as $child)
    render_select($child, $level+1);
}

echo  <select> ;
render_select();
echo  </select> ;

1. More efficient hierarchy system

Though this is an old question, I m gonna post my answer here:

/* assuming top level pid = 0 */
$rows = array (
    array (  id  => 1,  pid  => 0 ),
    /* ... */
);

/* make id become array key */
$rows = array_column ( $rows, null,  id  ); 

foreach ( $rows as $key => $val ) {
    if ( $val [ pid ] ) {
        if ( isset ( $rows [$val [ pid ]] )) {
            $rows [$val [ pid ]][ children ][] = &$rows [$key];
        }
    }
}

foreach ( $rows as $key => $val ) {
    if ( $val [ pid ] ) unset ( $rows [$key] );
}

array_column> 是PHP.5,但你可以方便地自行选择。

这是我的解决办法、复制和优化其他解决办法。

function buildTree(array &$elements, $parentId = 0) {
    $branch = array();
    foreach ($elements as $key => $element) {
        if ($element[ parent_id ] == $parentId) {
            $children = $this->buildTree($elements, $key);
            if ($children) {
                $element[ children ] = $children;
            }
            $branch[$key] = $element;
            unset($elements[$key]);
        }
    }
    return $branch;
}

你们想看一下在我的SQL中储存和装上等级数据的问题,因为我要解决几个问题。 我假定第一个阵列是数据库直接提供的数据吗?

It looks like you re trying to use the adjacency model to organize your data into the hierarchy structure. There are also other ways to achieve this using nesting. If you are not taking this data from a database then this may not be as useful.

这一联系应有助于您:http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/“rel=“nofollow”http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/。