PHP:如何将递归函数的结果保存在数组中？

Question

我已经更改了这个递归函数的版本..。http://www.phpbuilder.com/articles/databases/mysql/handling-hierarchical-data-in-mysql-and-php.html

我需要的是一种将这个函数的返回值保存在数组中的方法，这样我就可以反转数组元素的顺序。这个函数对我来说很好，但是我需要一种保存值的方法。这是密码..。

function display_children($category_id, $level) {
  global $database;
  $result = mysql_query("SELECT * FROM parents WHERE id_roditelja='$category_id'") or die(mysql_error());
  $niz = array();
  while ($row = mysql_fetch_array($result)) {
    echo str_repeat('  ', $level) . $row['naziv'] . "<br/>";
    array_push($niz, display_children($row['parent_id'], $level + 1));
//this is one way I tried, and I get $niz with exact number of elements but each is null
//in this $niz array I need to store values of recursion
    var_dump($niz);
  }
}

Answer 1

我想你想要这个：

function display_children/* <- this must be the same */($category_id, $level) {
  global $database;
  $result = mysql_query("SELECT * FROM parents WHERE id_roditelja='$category_id'") or     die(mysql_error());
  $niz = array();
  while ($row = mysql_fetch_array($result)) {
    $niz[] = str_repeat('  ', $level) . $row['naziv'] . "<br/>"; // we need to save this
    $niz = array_merge($niz, /* as this -> */display_children($row['parent_id'], $level + 1)); // array_merge doesn't take a reference so we need to store its result in $niz
  }
  return $niz;
}

如果您想要树状结构，请使用array_push而不是array_merge。似乎没有人注意到:如果没有返回语句，他的函数就不能返回任何东西！