Help with recursion

You can use a variable by reference then you do not have to return it

@AHMEDDABAK - Any examples, links, anything at all?

function do_this($a, $to_return = [])
{
    // do some stuff

    if(condition) {
               return do_this(&$a, &$to_return);
    }

    return $to_return;
}

add an & before a variable in the function call... I added it to both variables as I have no clue which would be modified by the call...

Can you describe your logic? Why do you need the $to_return array at all?

If you provide us a bit more meat and potatoes to what you are trying to accomplish, we may be able to help more.

There are times where recursion is actually not required and there are better ways to accomplish things.

    /**
     * Get a list of titles from a Wikipedia Category
     *
     * @param  string $title     [description]
     * @param  array  $to_return [description]
     * @return [type]            [description]
     */
    public function getCategoryList(string $title, string $continue = '', array $to_return = []): array
    {
        $title    = str_replace('_', ' ', $title);
        $response = $this->getResponseFromWikipedia('category', str_start($title, 'Category:') . $continue);

        foreach ($response['query']['categorymembers'] as $place) {
            if ($place['title'] != $title and !preg_match('/^User/i', $place['title'])) {
                $to_return[] = $place['title'];
            }
        }

        if (isset($response['continue'])) {
        // HERE
            return $this->getCategoryList($title, '&cmcontinue=' . $response['continue']['cmcontinue'], $to_return);
        }

        return $to_return ?? [];
    }

Nothing gets passed to the $to_return variable initially, it is only there for the recursion, to build up the array

I was just wondering if there was a way to not have to pass it

@jackjones

Can you give me an example of each variable?

$title, $continue... of this function call. I think I know what you want to do here, but I need to verify with these variables... and then I should be able to help you.

Perhaps you could use a class variable instead?

private $some_variable = [];

...and in your method:

$this->some_variable[] = "something"; // or something similar depending on your needs

@NASH - That is the other option but I was avoiding it because I wish being really strict about it i.e. the other methods don't need access to it (debatably unnecessarily and because my way works equally as well) and I wondered if there was another way

@CMDOBUENO - they are both strings ref:

getCategoryList(string $title, string $continue = ''

You could always extract it all to its own dedicated class with the sole responsibility of the recursion. Then you can set your class property within the dedicated class with confidence that nothing else will access it.

Here you go...... you just needeed to merge the result of the recursed function back into your $to_return variable ;)

    public function getCategoryList(string $title, string $continue = ''): array
    {
        $to_return = [];
        $title    = str_replace('_', ' ', $title);
        $response = $this->getResponseFromWikipedia('category', str_start($title, 'Category:') . $continue);

        foreach ($response['query']['categorymembers'] as $place) {
            if ($place['title'] != $title and !preg_match('/^User/i', $place['title'])) {
                $to_return[] = $place['title'];
            }
        }

        if (isset($response['continue'])) {
            // HERE
            $tmp = $this->getCategoryList($title, '&cmcontinue=' . $response['continue']['cmcontinue']);
            $to_return = array_merge($to_return, $tmp);
        }

        return $to_return ;
    }