Need a regular expression - disallow all zeros

Question

I want to validate a string to meet the following conditions:

• Must be 6 characters long
• Only the first character can be alpha-numeric the rest must be

Answer 1

You can use a (?!0+$) negative lookahead to avoid matching a string that only contains 1 or more zeros:

/^(?!0+$)[A-Z0-9][0-9]{5}$/
  ^^^^^^^

See the regex demo. This approach lets you just copy/paste the lookahead after ^ and not worry about how many chars the consuming part matches.

Details

• ^ - start of a string
• (?!0+$) - a negative lookahead that fails the match if there are 1 or more 0 chars up to the end of the string ($)
• [A-Z0-9] - an uppercase ASCII letter or a digit
• [0-9]{5} - five digits
• $ - end of string.

Answer 2

Just have a negative lookahead like this to disallow all 0s:

/^(?!0{6})[A-Z0-9][0-9]{5}$/

Answer 3

(?!000000)[A-Z0-9][0-9]{5} if lookahead is okay.

Answer 4

I think this will do it. It checks for not 000000 and your original regex.

(?!0{6})^[A-Z0-9][0-9]{5}$

Answer 5

What if you checked for the all zeros case first and then, after determining that it's no all zeros apply your regex?

if ( NOT ALL ZEROS)
    APPLY REGEX

Answer 6

I would do two passes. One with your first regex, and one with a new regex looking for all zeros.