Question

First up, I’m a N00b with Regex it’s like a new language that I’m struggling with ATM and looking for some direction.

I have a form that has a serial number field but the fields contents can be one of 3 possible rules.

Rule1 : Length is always 13 Position 1 is always C Positions 2-5 is
numeric Position 6 is alpha Position 7-13 is numeric

Rule2 : Length is 8 or 9 Position 1-2 is alpha Position 3-8 is numeric
Postion 9 is alpha

Rule3 : Length is 9 Position 1-9 is numeric

My question: is this of formula achievable inside regex – and sub question: Pointers for where I can look to or expressions I can decipher ?

Apologies if this is too n00b’esque – RegEx does my head in 🙂

Answer 1

Have a try with:

/^(C\d{4}[a-zA-Z]\d{7}|[a-zA-Z]{2}\d{6}[a-zA-Z]?|\d{9})$/

I suppose that the last alpha is optional in the rule #2

explanation:

The regular expression:

(?-imsx:^(C\d{4}[a-zA-Z]\d{7}|[a-zA-Z]{2}\d{6}[a-zA-Z]?|\d{9})$)

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    C                        'C'
----------------------------------------------------------------------
    \d{4}                    digits (0-9) (4 times)
----------------------------------------------------------------------
    [a-zA-Z]                 any character of: 'a' to 'z', 'A' to 'Z'
----------------------------------------------------------------------
    \d{7}                    digits (0-9) (7 times)
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    [a-zA-Z]{2}              any character of: 'a' to 'z', 'A' to 'Z'
                             (2 times)
----------------------------------------------------------------------
    \d{6}                    digits (0-9) (6 times)
----------------------------------------------------------------------
    [a-zA-Z]?                any character of: 'a' to 'z', 'A' to 'Z'
                             (optional (matching the most amount
                             possible))
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    \d{9}                    digits (0-9) (9 times)
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------