UK Postcode Regex (Comprehensive)

Question

I'm after a regex that will validate a full complex UK postcode only within an input string. All of the uncommon postcode forms must be covered as well as the usual. For instance:

Matches

• CW3 9SS
• SE5 0EG
• SE50EG
• se5 0eg
• WC2H 7LT

No Match

• aWC2H 7LT
• WC2H 7LTa
• WC2H

Are there any official or even semi-official regexes in use for this kind of thing? Any other advice as to formatting and storing these in a database?

Answer 1

^([A-PR-UWYZ0-9][A-HK-Y0-9][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]? {1,2}[0-9][ABD-HJLN-UW-Z]{2}|GIR 0AA)$

Regular expression to match valid UK postcodes. In the UK postal system not all letters are used in all positions (the same with vehicle registration plates) and there are various rules to govern this. This regex takes into account those rules. Details of the rules: First half of postcode Valid formats [A-Z][A-Z][0-9][A-Z] [A-Z][A-Z][0-9][0-9] [A-Z][0-9][0-9] [A-Z][A-Z][0-9] [A-Z][A-Z][A-Z] [A-Z][0-9][A-Z] [A-Z][0-9] Exceptions Position - First. Contraint - QVX not used Position - Second. Contraint - IJZ not used except in GIR 0AA Position - Third. Constraint - AEHMNPRTVXY only used Position - Forth. Contraint - ABEHMNPRVWXY Second half of postcode Valid formats [0-9][A-Z][A-Z] Exceptions Position - Second and Third. Contraint - CIKMOV not used

http://regexlib.com/REDetails.aspx?regexp_id=260

Answer 2

I'd recommend taking a look at the UK Government Data Standard for postcodes (http://www.govtalk.gov.uk/gdsc/html/frames/Postcode.htm). There is a brief description about the data and the attached xml schema provides a regular expression. It may not be exactly what you want but would be a good starting point.

Answer 3

First half of postcode Valid formats

• [A-Z][A-Z][0-9][A-Z]
• [A-Z][A-Z][0-9][0-9]
• [A-Z][0-9][0-9]
• [A-Z][A-Z][0-9]
• [A-Z][A-Z][A-Z]
• [A-Z][0-9][A-Z]
• [A-Z][0-9]

Exceptions
Position 1 - QVX not used
Position 2 - IJZ not used except in GIR 0AA
Position 3 - AEHMNPRTVXY only used
Position 4 - ABEHMNPRVWXY

Second half of postcode

• [0-9][A-Z][A-Z]

Exceptions
Position 2+3 - CIKMOV not used

Remember not all possible codes are used, so this list is a necessary but not sufficent condition for a valid code. It might be easier to just match against a list of all valid codes?

Answer 4

Have a look at the python code on this page:

http://www.brunningonline.net/simon/blog/archives/001292.html

I've got some postcode parsing to do. The requirement is pretty simple; I have to parse a postcode into an outcode and (optional) incode. The good new is that I don't have to perform any validation - I just have to chop up what I've been provided with in a vaguely intelligent manner. I can't assume much about my import in terms of formatting, i.e. case and embedded spaces. But this isn't the bad news; the bad news is that I have to do it all in RPG. :-(

Nevertheless, I threw a little Python function together to clarify my thinking.

I've used it to process postcodes for me.