[RESOLVED] Validating Postal Codes/ZipCodes; Best way?

Rivet

Hi all,

I'm attempting to check for US and Canadian zip codes (postal codes) to start with. The US is easy; mostly just be sure it's five numerics and except "00000" and "99999". But Canadian is a different story because:

It consists of alternating alpha and numeric characters (AnAnAn) but not the entire alphabet. 8 N.A. English letters are not used, as in DFIOQUW AND Z or put another way, they only use 18 letters in their postal codes.
I haven't see a single example in all my research to check if the 1st, 3rd, and 5th characters are alpha and th 2nd, 4th and 6th characters are numeric. They all assume A-Z(lower case not allowed).

I've tried preg_match and strpos without succees, likely due to my own weakness with preg_match, and regex creates an incredibly long statement I'm sure it's not right to put upon the servers; they slow down even my local server XAMPP & PHP 5.3 on win 7.

Might anyone have a better method?

Or know of any functions anywhere that could be modified to be used?

One source mentioned using Ctype but I can't see how to apply it here. And I thought strpos() was going to be my savior, but can't get it to work.

Eventually I'll be adding other postal codes so this is my beginning foray into the situation. The purpose is to relate a country to a postal code for later comparison to the country they purport to be from.

TIA,

Rivet

bradgrafelman

Sounds like a regexp pattern like:

/^(?:[A-CEGHJ-NPR-TVX][0-9]){3}$/

could be used to validate the form of a given Canadian postal code based on the description you gave. (Whether or not the postal code is truly valid/used is, of course, another matter altogether.)

EDIT: Note that the pattern assumes no whitespace is used in order to simplify the pattern. It would not, for example, account for the apparently common format of "AnA nAn". In addition, I also mirror dalecosp's suggestion below to determine whether using an external API might be better since that also covers the issue of having a valid postal code versus one that could be valid based on a pattern.

dalecosp

I've used a program called "The Regex Coach" for a couple years now and my regexp-fu has increased somewhat as a result. Of course, the real reason I got it wasn't to learn, but to have it do them for me ;-)

One idea might be a dual-layer check? Have your function check for the existence of a forbidden character; if so, return false ... then do a regexp check, return true if a match, else return false.

All that being said, I see that Canada Post has an API (and I'm fairly sure the USPS does, too) ... you might actually check validity with the code issuing authority at the time of submission....

Rivet

dalecosp, that puts a neat face on things; I like it!

I did come across their API but since this is the beginning of validating several country's postal codes, I downoaded the information I need and will look into it in the future. Mostly because I don't know how to do it. Yet 🙂, but I will come back to it. It would do away with having to worry about changes to the codes in the future. Excellent response.

Rivet`

Thanks much,

Rivet

bradgrafelman;11032397 wrote:
Sounds like a regexp pattern like:
/^(?:[A-CEGHJ-NPR-TVX][0-9]){3}$/
could be used to validate the form of a given Canadian postal code based on the description you gave. (Whether or not the postal code is truly valid/used is, of course, another matter altogether.)

EDIT: Note that the pattern assumes no whitespace is used in order to simplify the pattern. It would not, for example, account for the apparently common format of "AnA nAn". In addition, I also mirror dalecosp's suggestion below to determine whether using an external API might be better since that also covers the issue of having a valid postal code versus one that could be valid based on a pattern.

It would.

NogDog

Don't forget that US codes could be "nnnnn-nnnn". 🙂