Goal: RegEx to fit many posible NDC 10 & 11 formats.

I've made a great start... NDC 10:

^[0-9][0-9][0-9][0-9]\-[0-9][0-9][0-9][0-9]\-[0-9][0-9]$

e.g. 1234-1234-12 Reference

However, I've since learnt there are other formats and 11 digits:

• 4-4-2
• 5-3-2
• 5-4-1
• 5-4-2 (11 digits)

How can I write one RegEx for all these possibilities?

Issues:

1. Optional 11th digit,
2. Moving hyphen

CodePudding user response：

You can use

^(?:\d{4}-\d{4}-\d{2}|\d{5}-(?:\d{3}-\d{2}|\d{4}-\d{1,2}))$

See the regex demo. Details:

• ^ - start of string
• (?: - start of the first non-capturing group:
  • \d{4}-\d{4}-\d{2} - four digits, -, four digits, -, two digits
  • | - or
  • \d{5}- - five digits, -
  • (?: - start of the second non-capturing group:
    • \d{3}-\d{2} - three digits, -, two digits
    • | - or
    • \d{4}-\d{1,2} - four digits, - and one or two digits
  • ) - end of the second non-capturing group
• ) - end of the first non-capturing group.
• $ - end of string.