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Regex extraction from Right to Left

I have some data where I like to extract data from right to left. Sample data

1,4,34
5,15
22

Expected output:

One=34  Two=4  Three=1
One=15  Two=5
One=22

This is as far as I have got with my regex experience.

(?:(?<three>\d+),)?(?:(?<two>\d+),)?(?<one>\d+)$

But this gives :

One=34  Two=4  Three=1
One=15  Three=5
One=22

So it fails when there are only two extraction. Any good idea? PS I do not have any revers tools

Solution

  • You can make the first 2 groups optional as a whole:

    ^(?:(?:(?<three>\d+),)?(?<two>\d+),)?(?<one>\d+)$

    The pattern matches:

    • ^ Start of string
    • (?: Non capture group
      • (?:(?<three>\d+),)? Optionally capture 1+ digits in group "three" and match a comma
      • (?<two>\d+), Capture 1+ digits in group "two" and match a comma
    • )? Close the non capture group
    • (?<one>\d+) Capture 1+ digits in group "one"
    • $ End of string

    Regex demo