PHP: how to save result of recursive function in array?

Question

I have changed version of this recursive function... http://www.phpbuilder.com/articles/databases/mysql/handling-hierarchical-data-in-mysql-and-php.html

What I need is a way to save the returned value of this function in an array so that I can reverse the order of array elements. The function works well for me, but I need a way to save values. Here is the code...

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);
  }
}

Christoph Diegelmann · Accepted Answer · 2013-08-30 11:13:04Z

2

I think you want this:

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;
}

if you want a tree like structure use array_push instead of array_merge. As noone seems to notice: His function can't return anything without a return statement !

edited Aug 30, 2013 at 11:13

answered Aug 28, 2013 at 9:02

Christoph Diegelmann

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15 Comments

Ivan Yonkov Over a year ago

As maybe we have already noticed that, but in comments, because one more row, does not deserve a whole answer :)

Thug Over a year ago

Same result as my way...null again. My function returns names of products, as it should, but i need it saved in array, because order of elements in not the right.

Christoph Diegelmann Over a year ago

@Thug your function (how you posted it) may display something but it won't return anything because it lacks a return statement ! Can you post how you call your function and an example output ?

Thug Over a year ago

This is example od output Zaštita za zube Borilački aksesoari Borilački sportovi Sportska oprema array 0 => null array 0 => null array 0 => null array 0 => null

Thug Over a year ago

i call function like display_chield(58,4);

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