recursion - Php doesn't break in a recursive foreach loop

Question

I have a recursive function like below.

public function findnodeintree($cats,$cat_id)
{       
    foreach($cats as $node)
    {                   
        if((int)$node['id'] == $cat_id)
        {       
            echo "finded";
            $finded = $node;
            break;
        }
        else
        {
            if(is_array($node) && array_key_exists('children', $node)){ 
                $this->findnodeintree($node['children'],$cat_id);
            }
        }           
    }
    return $finded;
}

For Example

$node =$this->findnodeintree($category_Array, 169);

It gaves me

"founded"

A PHP Error was encountered

Severity: Notice

Message: Undefined variable: finded

Array Structure is like

    [0] => Array
    (
        [id] => 0
        [name] => MAIN CATEGORY
        [depth] => 0
        [lft] => 1
        [rgt] => 296
        [children] => Array
            (
                [0] => Array
                    (
                        [id] => 167
                        [name] =>  CAT 0
                        [depth] => 1
                        [lft] => 2
                        [rgt] => 17
                        [children] => Array
                            (
                                [0] => Array
                                    (
                                        [id] => 169
                                        [name] =>   CAT 1
                                        [depth] => 2
                                        [lft] => 3
                                        [rgt] => 4
                                    )

                                [1] => Array
                                    (
                                        [id] => 170
                                        [name] =>   CAT 2
                                        [depth] => 2
                                        [lft] => 5
                                        [rgt] => 10
                                        [children] => Array
                                            (
                                                [0] => Array
                                                    (
                                                        [id] => 171
                                                        [name] =>    CAT 5
                                                        [depth] => 3
                                                        [lft] => 6
                                                        [rgt] => 7
                                                    )

                                                [1] => Array
                                                    (
                                                        [id] => 172
                                                        [name] =>    CAT 3
                                                        [depth] => 3
                                                        [lft] => 8
                                                        [rgt] => 9
                                                    )

                                            )

                                    )

Answer 1

To get the right value from recursion, your recursion call must not discard the return value. And since you want to walk back up the recursion tree as soon as you get a hit, and actually return the matching node, you have to break your loop at that point too.

Otherwise subsequent recursion calls overwrite your variable and the wrong node, false, or null is returned.

This should be what works:

public function findnodeintree($cats,$cat_id)
{       
    foreach($cats as $node)
    {                   
        if((int)$node['id'] == $cat_id){       
            return $node;
        }
        elseif(array_key_exists('children', $node)) {
            $r = $this->findnodeintree($node['children'], $cat_id);
            if($r !== null){
                return $r;
            }
        }           
    }
    return null;
}

Note: I removed the is_array because at that point $node has to be an array or throw an error at the first branch condition.