PO Box Validation

Question

Looking to validate PO Box but wanted to know if such validation existed. I have the Address field split into Address 1 and Address 2 (Where such PO, Apt, Suite info would go)

Answer 1

Let's go through it...

/         # Beginning of the regex
^         # Beginning of the string
\s*       # (Any whitespace)
((
  P       # Matches your P
  (OST)?  # Matches your ost
  .?      # Matches the space
  \s*     # (Any whitespace)
  O       # Expects an O - you don't have one. Regex failed.