Regex to match URL end-of-line or "/" character
RegexRegex Problem Overview
I have a URL, and I'm trying to match it to a regular expression to pull out some groups. The problem I'm having is that the URL can either end or continue with a "/" and more URL text. I'd like to match URLs like this:
- http://server/xyz/2008-10-08-4
- http://server/xyz/2008-10-08-4/
- http://server/xyz/2008-10-08-4/123/more
But not match something like this:
So, I thought my best bet was something like this:
/(.+)/(\d{4}-\d{2}-\d{2})-(\d+)[/$]
where the character class at the end contained either the "/" or the end-of-line. The character class doesn't seem to be happy with the "$" in there though. How can I best discriminate between these URLs while still pulling back the correct groups?
Regex Solutions
Solution 1 - Regex
To match either / or end of content, use (/|\z)
This only applies if you are not using multi-line matching (i.e. you're matching a single URL, not a newline-delimited list of URLs).
To put that with an updated version of what you had:
/(\S+?)/(\d{4}-\d{2}-\d{2})-(\d+)(/|\z)
Note that I've changed the start to be a non-greedy match for non-whitespace ( \S+? ) rather than matching anything and everything ( .* )
Solution 2 - Regex
You've got a couple regexes now which will do what you want, so that's adequately covered.
What hasn't been mentioned is why your attempt won't work: Inside a character class, $ (as well as ^, ., and /) has no special meaning, so [/$] matches either a literal / or a literal $ rather than terminating the regex (/) or matching end-of-line ($).
Solution 3 - Regex
/(.+)/(\d{4}-\d{2}-\d{2})-(\d+)(/.*)?$
1st Capturing Group (.+)
.+ matches any character (except for line terminators)
+Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)
2nd Capturing Group (\d{4}-\d{2}-\d{2})
\d{4} matches a digit (equal to [0-9])
{4}Quantifier — Matches exactly 4 times
- matches the character - literally (case sensitive)
\d{2} matches a digit (equal to [0-9])
{2}Quantifier — Matches exactly 2 times
- matches the character - literally (case sensitive)
\d{2} matches a digit (equal to [0-9])
{2}Quantifier — Matches exactly 2 times
- matches the character - literally (case sensitive)
3rd Capturing Group (\d+)
\d+ matches a digit (equal to [0-9])
+Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)
4th Capturing Group (.*)?
? Quantifier — Matches between zero and one times, as many times as possible, giving back as needed (greedy)
.* matches any character (except for line terminators)
*Quantifier — Matches between zero and unlimited times, as many times as possible, giving back as needed (greedy)
$ asserts position at the end of the string
Solution 4 - Regex
In Ruby and Bash, you can use $ inside parentheses.
/(\S+?)/(\d{4}-\d{2}-\d{2})-(\d+)(/|$)
(This solution is similar to Pete Boughton's, but preserves the usage of $, which means end of line, rather than using \z, which means end of string.)