Regex for two years separated by a forward slash

Question

I am new to learning Regex and I am struggling with this basic issue. I want to make sure a string is in a format like: 2000/2001 or 2010/2011.

I tried something like: ^[2000-2900]./.[2000-2900]$ but I know this is wrong!

[What have you tried?](http://mattgemmell.com/2008/12/08/what-have-you-tried/) — Simon, Mar 14 '13 at 17:08
You're struggling - What have you tried? What platform are you using? Did you forgot to escape the slash? — Bergi, Mar 14 '13 at 17:08
You must tag the programming language you're using, otherwise there's no way of telling what regex patterns will work for you. — zzzzBov, Mar 14 '13 at 17:10
possible duplicate of [Regular Expression: Numeric range](http://stackoverflow.com/questions/1377926/regular-expression-numeric-range); read http://www.regular-expressions.info/numericranges.html — Bergi, Mar 14 '13 at 17:11
If you're going to build a regular expression you should be using a test-driven approach, define a set of input values that should pass, and, more importantly, a set of input values that should fail. — zzzzBov, Mar 14 '13 at 17:12
Btw, here's a good tool for learning regex: http://regexpal.com/ (check out the quick reference menu on top right) — Simon, Mar 14 '13 at 17:22

score 6 · Accepted Answer · answered Mar 14 '13 at 17:11

6

This would be the very basic:

^\d{4}\/\d{4}$

From the beginning of the string, check if it has 4 digits followed by a "/" (escaped with "\") and another 4 digits to the end of the string.

answered Mar 14 '13 at 17:11

Simon

This might be valid, but there's no way of telling unless OP provides more data. `0000/0000` would be matched, but might not be valid. – zzzzBov Mar 14 '13 at 17:13
Yeah the OP asked for a format regex. – Simon Mar 14 '13 at 17:16
1

Yes, but you can see the provided example shows a tendency toward numbers in the range of `2000-2900`. – zzzzBov Mar 14 '13 at 17:17

score 1 · Answer 2 · answered Mar 14 '13 at 17:20

If you searching for where the entire string must match then:

^\d{4}/\d{4}$

If you are searching for a sub string of a larger string then:

\d{4}/\d{4}

And if you using in C# then remember to wrap it up in a verbatim string like so:

@"^\d{4}/\d{4}$"
@"\d{4}/\d{4}"

I noticed that others are escaping the forward slash but I don't think is necessary but doesn't do any harm if you do.

2 Answers2