On 17 February 2004 10:43, Roddie Grant wrote:
> on 17/2/04 10:25 am, Shaun at [EMAIL PROTECTED] wrote:
>
> > Hi,
> >
> > does anyone know the format of the postcodes in the UK so I can
> > keep my database accurate?
> >
> > Thanks
>
>
> Try http://javascript.internet.com/forms/uk-postcode-validation.html
Wow, at a glance I'd say that looks like pretty crappy JavaScript, and also not a
totally accurate UK postcode checker.
The only guaranteed way to fully validate a UK postcode is to purchase the Royal
Mail's Postcode Address File (PAF) (and subscribe to its updates!), but you can
validate the format fairly closely with some simple rules.
For example, here's a regexp that matches valid UK postcode patterns:
/[A-Z]{1,2}[0-9][0-9A-Z]? [0-9][ABD-HJLNP-UW-Z]{1,2}/
or, in English:
* an "outward" code consisting of:
- 1 or 2 alphabetic characters
- followed by 1 or 2 digits, or 1 digit and 1 letter
* a space
* in "inward" code consisting of:
- 1 digit
- followed by 2 letters, but not including C, I, K, M, O or V.
(The special code GIR 0AA also exists for the headquarters of the
formerly-Government-owned Girobank, now part of the Alliance & Leicester, and is the
only one that doesn't match these rules).
Although this will check for potentially valid formats, there are a number of other
checks you can make if you wish:
- the initial 1 or 2 letters come from a restricted set of about 120, indicating the
main sorting office which handles mail for an area -- generally they correspond to a
large town or city (B - Birmingham, L - Liverpool, LS - Leeds, etc.) but London ones
are taken from the much older London postal district names (E - East, EC - East
Central, etc.) and a few represent more general area names (ZE - Shetland Islands, for
example. (I could probably produce a list of these fairly easily.)
- The range of values in the rest of the "outward" code is likewise restricted; the
range is different for each area, with many restricted to 20 or less, and none uses
the full set of 1-99; however, higher values are often used for special purposes (98
and 99 for PO Boxes, for example), and most of the larger areas have multiple disjoint
ranges.
- The only postcodes which have a final letter in the "outward" portion of the code
are some of the London districts (off the top of my head, EC, SW, W and WC only, I
think, and maybe not all of those!).
- For each "outward" code, there may also be restrictions on the range of "inward"
codes, and these will again be different for each area (for example, for my home
outward code all inward codes begin with a 2; in the neighbouring outward code, all
inward codes begin with a 3). These are so numerous and diverse that they're not
really worth bothering about unless you're going the full-blown PAF route.
Anyway, this is probably already far more information than you were expecting, so I'll
shut up now!
Cheers!
Mike
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Mike Ford, Electronic Information Services Adviser,
Learning Support Services, Learning & Information Services,
JG125, James Graham Building, Leeds Metropolitan University,
Beckett Park, LEEDS, LS6 3QS, United Kingdom
Email: [EMAIL PROTECTED]
Tel: +44 113 283 2600 extn 4730 Fax: +44 113 283 3211
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