C# Regex, how can I check that a regex group contains only digits

Question

I made the following regex pattern in C#:

Regex pattern = new Regex(@"(?<prefix>retour-)?(?<trackingNumber>\s*[0-9]+\s*)(?<postfix>-([0]|[1-9]{1,2}))?");

(?<prefix>retour-)?(?<trackingNumber>\s*[0-9]+\s*)(?<postfix>-([0]|[1-9]{1,2}))?

• This is what I want: Three groups.
  • The prefix group is "retour-" and if it occurs it is at the beginning.
  • The trackingNumber group is mandatory and should consist only of digits.
  • The postfix group is "-" followed only by digits, it is not mandatory.
• I want the trackingNumber group to be a success only if it contains numbers. The same goes for the postfix. In a similar question, the problem was solved by using regex anchors (^, $) but in my case I cannot use them because the trackingNumber group starts in the middle.

For example:

• "1234ABC3456" should not be a success
• "retour-123456-12B" should also not be a success

The problem is that the regex (?<trackingNumber>\s*[0-9]+\s*) will return a success even for a series that does not contain only digit numbers.

Answer 1

This pattern works for me:

^(?<prefix>retour-)?\s*(?<trackingNumber>\d+)\s*(?<postfix>-(\d+))?$

Input	Result
1234ABC3456	No match
retour-123456-12B	No match
retour-123456-123	prefix: "retour-", trackingNumber: "123456", postFix: "-123"
543210-999	trackingNumber: "543210", postFix: "-999"
987654	trackingNumber: "987654"

https://regex101.com/r/Fo1pvU/1