Question

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:

• http://server/xyz/2008-10-08-4-1

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?

Answer 1

/(.+)/(\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