Regex: Match Optional URI Parameters

Question

Take a given URI, like this:

one/two/three

How would I match each character, in a capture group, between the slashes? This can be done with this method:

(.+)\/(.+)\/(.+)

This gives me three groups where:

$1 = one
$2 = two
$3 = three

What I am having trouble with is making a capture group optional. I thought that this would work, thinking I could make each group optional (match zero or more):

(.+)?\/(.+)?\/(.+)?

Is there a way, using Regex or PHP to optionally match parts one, two or three of the above URI?

Wiktor Stribiżew · Accepted Answer · 2015-03-31 08:35:16Z

1

You can use the following regex

^(?:(.+?))?(?:\/(.+?))?(?:\/(.+?))?$

This will make all groups optional. The main point is using non-capturing groups with ? quantifier, and .+? patterns to capture each part into separate group, so that you could reference them later with $n.

See example.

Sample code:

$re = "/^(?:(.+?))?(?:\\/(.+?))?(?:\\/(.+?))?$/m"; 
$str = "one/two/three\none/two\none\n\n"; 
preg_match_all($re, $str, $matches);

edited Mar 31, 2015 at 8:35

answered Mar 31, 2015 at 8:25

Wiktor Stribiżew

631k41 gold badges502 silver badges632 bronze badges

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

2 Comments

James Craig Over a year ago

This matches parts one, two or three optionally, however I wanted each matched part (one, two or three) inside a capture group so I can reference them using $1, $2, or $3. Is this possible?

Wiktor Stribiżew Over a year ago

Ok, I think I will just make answer a bit shorter. :). All you need is to use non-greedy quanifiers (with .+?).

Collectives™ on Stack Overflow

Regex: Match Optional URI Parameters

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related