PHP preg_match with optional math rules

Question

I want to parse this string and get special values string to parse have one of these patterns

app/(integer)/(integer)/(text or null)
app/(integer)/(text or null)
app/(text or null)

I can use preg_match for simple use but I can't write optional params

preg_match('%app/(\d+)/(\d+)/(\.*)$%', $text, $matches)

Answer 1

I'd do:

$urls = array(
    'app/12/34/text',
    'app/12/34/',
    'app/56/text',
    'app/56/',
    'app/text',
    'app/',
);
foreach ($urls as $url) {
    preg_match( "#app/(?:(\d+)/)?(?:(\d+)/)?(.*)#", $url, $m);
    print_r($m);
}

Output:

Array
(
    [0] => app/12/34/text
    [1] => 12
    [2] => 34
    [3] => text
)
Array
(
    [0] => app/12/34/
    [1] => 12
    [2] => 34
    [3] =>
)
Array
(
    [0] => app/56/text
    [1] => 56
    [2] =>
    [3] => text
)
Array
(
    [0] => app/56/
    [1] => 56
    [2] =>
    [3] =>
)
Array
(
    [0] => app/text
    [1] =>
    [2] =>
    [3] => text
)
Array
(
    [0] => app/
    [1] =>
    [2] =>
    [3] =>
)

Answer 2

Your given patterns result in the following cases u want to match:

app/1/2/foo
app/1/2/
app/1/bar
app/1/
app/bar
app/

This can be achieved using a regex with the OR operator ( | ). Syntax would be as follows:

~app/(\d+)/(\d+)/(\w+)|app/(\d+)/(\d+)/|app/(\d+)/(\w+)|app/(\d+)/|app/(\w+)|app/$~

I built a regex101 "fiddle" for exactly your case: http://regex101.com/r/zT9jT6/1

Note that "app/" will match match with 0 entries in your $matches array.

et voilà.