Loop into multidimensional array from top to bottom - php

Question

I have this tree :
Array
(
[0] => Array
(
[id] => 1
[parent_id] => 0
[title] => Parent Page
[children] => Array
(
[0] => Array
(
[id] => 2
[parent_id] => 1
[title] => Sub Page
),
[1] => Array
(
[id] => 5
[parent_id] => 1
[title] => Sub Page 2
)
)
)
[1] => Array
(
[id] => 4
[parent_id] => 0
[title] => Another Parent Page
)
)
And I'm looking for a display from top to bottom.
And display something like this :
1
1.2
1.5
4
But if I have id 3 which is a leaf from 5 I would like this :
1
1.2
1.5
1.5.3
4
I have search a lot and my brain is limited when i'm using recursivity..
I have tried this :
function printAll($a){
foreach ($a as $v){
if (!array_key_exists('children', $v)){
debugLog($v['id']);
return;
}
else{
$arrayChildrens = $v['children'];
foreach($arrayChildrens as $c){
$arrayChildrens = $c['children'];
$this->printAll($arrayChildrens);
}
}
}
}
But doesn't work..
I tried to begin just to display
1
2
5
4
But my goal is to display id parents before id ( like Ishowed you before)
Thanks a lot !

Answer 1

This function should give you your expected output.
function printAll($a, $prefix = '') {
//loop through $a
foreach($a as $v) {
//echo current level `id` with previous `$prefix`
echo "{$prefix}{$v['id']}\n";
//check if current level contains children
if(!empty($v['children'])) {
//clean up prefix to remove extra `.` at the end of prefixes
$prev_prefix = rtrim($prefix, '.');
//recurse printAll again passing the children as `$a` and a `$prefix` being the previous levels combined e.g `1.5`
//also clean up extra periods at the start of the prefix
printAll($v['children'], ltrim("{$prev_prefix}.{$v['id']}.", "."));
}
}
}
Output:
1
1.2
1.5
1.5.3
4
Using a proper return
Usually with a function you actually want the function to return values instead of echoing them automatically to your page. If you want this function to return an array of values instead of echoing them, you could do this:
function printAll($a, $level = '', $values = []) {
foreach($a as $v) {
$values[] = $value = "{$level}{$v['id']}";
if(!empty($v['children'])) {
$values = printAll($v['children'], "{$value}.", $values);
}
}
return $values;
}
Which will have a result like this:
Array
(
[0] => 1
[1] => 1.2
[2] => 1.5
[3] => 1.5.3
[4] => 4
)

Answer 2

This should do the job.
$arr = array(
array(
'id' => 1,
'parent_id' => 0,
'title' => 'Parent Page',
'children' => array(
array(
'id' => 2,
'parent_id' => 1,
'title' => 'Sub Page',
),
array(
'id' => 5,
'parent_id' => 1,
'title' => 'Sub Page 2',
'children' => array(
array(
'id' => 7,
'parent_id' => 5,
'title' => 'Sub Page',
),
array(
'id' => 8,
'parent_id' => 5,
'title' => 'Sub Page 2',
)
)
)
)
),
array(
'id' => 4,
'parent_id' => 0,
'title' => 'Another Parent Page',
)
);
function printAll($arr, $parent = [])
{
if (is_array($arr)) {
foreach ($arr as $k => $v) {
if (isset($v['id'])) {
$parent[] = $v['id'];
echo implode('.', $parent) . PHP_EOL;
}
if (isset($v['children'])) {
printAll($v['children'], $parent);
}
array_pop($parent);
}
}
}
printAll($arr);
Output
1
1.2
1.5
1.5.7
1.5.8
4
Working demo.