I was asked by someone to code up a system that ensures a UK postcode goes into the DB perfectly formatted - the task was not to ensure that the postcode actually exists, simply to write it into the DB in a particular format:   1 or 2 letters  followed by 1 or 2 numbers followed by a space followed by 1 number followed by 2 letters and all in Uppercase.   Examples (of correctly formatted postcode):   AB1 2CD MN23 4NW E2 1TG   Here is the Problem (incorrectly formatted postcode):