URI segments passed in as method parameters skips segments with value as 0 (zero)

[fijas]

Describe the bug
URI segments passed in as method parameters doesn't seem to work as expected if the segment contains 0 (integer zero).

CodeIgniter 4 version
4.0.0-beta3

Affected module(s)
Controllers & Routing

Expected behavior, and steps to reproduce if appropriate
If the URI segment contains zero as it's value, the segment is skipped when passed in as the method parameter.

class TestController extends Controller {
    public function segmentTest($param1 = 'x', $param2 = 'y') {
        var_dump($param1);
        echo '<br/>';
        var_dump($param2);
    }
}

If the URL called is something like

test/segmentTest/0/abc, (notice the third segment is zero, so $param1 should be set as 0)

but the result was:

string(3) "abc"
string(1) "y"

whereas I was expecting something like:

string(1) "0"
string(1) "abc"

Is this intentional? I couldn't find anything in the documentation. There are multiple situations where passing in 0 as the url param is valid.

Also please note that if no default values are given for the parameters, an error is encountered:

ArgumentCountError
Too few arguments to function App\Controllers\Test::segmentTest(), 1 passed in 

Context

• OS: Linux
• PHP version - 7.2.17

[InsiteFX]

Each section of the path between the slashes is a single segment. The URI class provides a simple way to determine what the values of the segments are. The segments start at 1 being the furthest left of the path.

[fijas]

Sorry if my question was not clear. I understand how segments work. My issue is that if the value of a segment is 0, then that value is not passed to the controller as a method parameter and the next segment if any is passed instead. The example I've given in the bug report illustrates the problem. I've edited the issue to try and make it a bit more clear...

[fijas]

So i've tracked down why this happens and the following line is where the 0 valued segments are filtered out:

CodeIgniter4/system/Router/Router.php

Line 571 in 230c2ab

$segments = array_filter($segments);

This line will filter out any values that evaluate to FALSE. So 0s will get dropped. I think that having 0s in the URL are valid and should not be filtered out.