CODEWITHSUNDEEP
.netregex
Glen Little
Glen Little

Reputation: 7128

Regular expression with groups?

In .NET, I'm trying to parse strings like these into groups of numbers. The "a" and "b" are optional (but fixed) letters:

111a222b333   --> groups: num1=111, num2=222, num3=333
111           --> groups: num1=111
111b333       --> groups: num1=111, num3=333
b333          --> groups: num3=333

The regular expressions I've tried include:

(?<num1>\d+)?a?(?<num2>\d+)?b?(?<num3>\d+)?
(?<num1>\d+)*.*(a(?<num2>\d+))*.*(b(?<num3>\d+))*

But they are not working. Any suggestions?

Upvotes: 0

Views: 63

Answers (3)

vallentin
vallentin

Reputation: 26157

You need combine the ? (zero or one of) so to speak in a group (not a capture group).

Thus turning this:

a?(?<num2>\d+)

Into:

(?:a(?<num2>\d+))?

The full regex would then be:

(?<num1>\d+)?(?:a(?<num2>\d+))?(?:b(?<num3>\d+))?

Here's a live preview.

As you can see it correctly yields:

Upvotes: 2

Yuriy Faktorovich
Yuriy Faktorovich

Reputation: 68667

(?<num1>\d*)?a?(?<num2>\d*)?b?(?<num3>\d*)

You were close, just needed to cover the case when the digit isn't there.

Preview

Upvotes: 1

Explorer
Explorer

Reputation: 1

This is a similar post: Regular expression to match any character being repeated more than 10 times

/([0-9])\1*/ should match what you're looking for, since in .NET, quantifiers are greedy by default.

Upvotes: -1

Related Questions