How to ensure that a string contains numbers and letters by using RegEx

Question

I'm trying to match strings that either:

• Contains between 9 and 15 numbers (Only numbers)
• Contains between 6 and 15 numbers+letters (it must contain both, numbers and letters. Only letters is not a valid option).

I have the following regex: \b([0-9]{9,15})|([A-Za-z0-9]{6,15})\b which fails because the second part allows you to have a string with 6 numbers or 6 letters only.

Should be valid:

• 123456789
• 12345678Y
• Y234Y2

Should not be valid:

• 12345678
• 123X4
• ABCDEFGHYJ

Answer 1

You can use

^(?:[0-9]{9,15}|(?=[a-zA-Z]*[0-9])(?=[0-9]*[a-zA-Z])[A-Za-z0-9]{6,15})$

See the regex demo.

Details:

• ^ - start of string
• (?: - start of a non-capturing group:
  • [0-9]{9,15} - nine to 15 digits
  • | - or
  • (?=[a-zA-Z]*[0-9])(?=[0-9]*[a-zA-Z])[A-Za-z0-9]{6,15} - six to 15 alphanumeric chars with at least one digit and at least one letter
• ) - end of the group
• $ - end of string.