CODEWITHSUNDEEP
c#regex
John Jackson
John Jackson

Reputation: 23

c# Regular expression to capture word after a captured group

I have item numbers in the general form: 1-3 digits followed by optional lower case character followed by optional single digit followed by a word followed by optional single digit. For example, all of the following are legitimate item numbers: "21aRepair", "04iMod2", "04d1RR", "5", "07", "8a", "09b", "04g3"

I need to break these item numbers up into components of the form: Component 1) 1-3 digits followed by optional lower case character followed by optional single digit Component 2) a word Component 3) optional single digit

For example:

"21aRepair" should become "21a", "Repair", null

"04iMod2" should become "04i", "Mod", "2"

"04d1RR" should become "04d1", "RR", null

"5" should become "5", null, null

I have the following regex: (^\d{1,3}[a-z]?\d?) that works fine for component 1. I have tried several options for component 2 without success.

I thought the following: (?<=^\d{1,3}[a-z]?\d?)([a-zA-Z]*\d?) would work. Adding the lookbehind "(?<=" to the component 1 pattern should say "take whatever is after component 1", and the group ([a-zA-Z]*\d?) should match components 2 and 3. This does not yield the expected results. Can someone tell me where I am going wrong?

Upvotes: 2

Views: 77

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626802

You may consider using

^(\d{1,3}[a-z]?\d?)([a-zA-Z]*)(\d?)$

See the regex demo

Details:

  • ^ - start of string
  • (\d{1,3}[a-z]?\d?) - Group 1: component, 1 to 3 digits, an optional lowercase ASCII letter and an optional digit
  • ([a-zA-Z]*) - Group 2: word, zero or more ASCII letters
  • (\d?) - Group 3: an optional digit
  • $ - end of string

In C#, use

var m = Regex.Match(str, @"^(\d{1,3}[a-z]?\d?)([a-zA-Z]*)(\d?)$");

check if m.Success is true, and access the three groups using m.Groups[n].Value where n is the group ID.

Upvotes: 3

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