Build array with recursive php function

Question

I have a hierarchy or rooms and subrooms without a universal array mapping it out. Instead I connect the ids of parent to child. So I need to use a recursive php function to loop through subrooms of a room and the subrooms of each of those and on an on and then build an array of all their ids

If I were just going to output each id as a string, I'd do it like this

function get_all_child_subrooms_recursive($rid) {
    $subrooms = get_all_subrooms($rid); // a function that grabs an array of direct children room id's to the parent room ($rid)
    if ($subrooms == "") {
        return;
    } else {
        foreach ($subrooms as $subroom) {
            $rid = $subroom;
            echo $rid .',';
            get_all_child_subrooms_recursive($rid);
        }
    }
}

But I need this data returned as a flat array containing all the id's

I want to output an array of all the ID's i grab. And I commented get_all_rooms(). It returns an array of direct children of the parent. But those children have children of their own and that's why I need this function. — Leopold
– Leopold, Commented Dec 19, 2019 at 16:57
you want just a flat array, or some sort of hierarchical structure in it? Please give sample input data, and expected output — ADyson
– ADyson, Commented Dec 19, 2019 at 17:06

Aroic · Accepted Answer · 2019-12-19 18:35:46Z

1

By flat array I'm assuming you mean a one dimensional array. What you have for outputting them as a string is a great start, just add them to an array with array_push():

$arr = array();
function get_all_child_subrooms_recursive($rid, &$arr) {
    $subrooms = get_all_subrooms($rid); // a function that grabs an array of direct children room id's to the parent room ($rid)
    if ($subrooms == "") {
        return;
    } else {
        foreach ($subrooms as $subroom) {
            array_push(arr, $subroom, get_all_child_subrooms_recursive($subroom, $arr));
        }
    }
}

edited Dec 19, 2019 at 18:35

answered Dec 19, 2019 at 17:50

Aroic

4812 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Aroic Over a year ago

You could either have the array be global, or pass in the array as an argument by reference with the & operator. I edited my answer to have the latter. Note: In PHP arrays are always passed by value by default (unlike C), and to pass by reference must be specified with &.

Leopold Over a year ago

I added an implementation of this to my answer but it's nor returning anything

Aroic Over a year ago

You need to add the $allSubrooms array to the recursive call in array_push(). My mistake, I missed that on my first edit. I added it to my example with $arr.

Collectives™ on Stack Overflow

Build array with recursive php function

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related