United Kingdom (GB) postal code validation without regex - php

I have tried several regexes and still some valid postal codes sometimes get rejected.
Searching the internet, Wikipedia and SO, I could only find regex validation solutions.
Is there a validation method which does not use regex? In any language, I guess it would be easy to port.
I supose the easiest would be to compare against a postal code database, yet that would need to be maintained and updated periodically from a reliable source.
Edit: To help future visitors and keep you from posting any more regexes, here's a regex which I have tested (as of 2013-04-24) to work for all postal codes in Code Point (see #Mikkel Løkke's answer):
//PHP PCRE (it was on Wikipedia, it isn't there anymore; I might have modified it, don't remember).
$strPostalCode=preg_replace("/[\s]/", "", $strPostalCode);
$bValid=preg_match("/^(GIR 0AA)|(((A[BL]|B[ABDHLNRSTX]?|C[ABFHMORTVW]|D[ADEGHLNTY]|E[HNX]?|F[KY]|G[LUY]?|H[ADGPRSUX]|I[GMPV]|JE|K[ATWY]|L[ADELNSU]?|M[EKL]?|N[EGNPRW]?|O[LX]|P[AEHLOR]|R[GHM]|S[AEGKLMNOPRSTY]?|T[ADFNQRSW]|UB|W[ADFNRSV]|YO|ZE)[1-9]?[0-9]|((E|N|NW|SE|SW|W)1|EC[1-4]|WC[12])[A-HJKMNPR-Y]|(SW|W)([2-9]|[1-9][0-9])|EC[1-9][0-9])[0-9][ABD-HJLNP-UW-Z]{2})$/i", $strPostalCode);

I'm writing this answer based on the wiki page.
When checking on the validation part, it seems that there are 6 type of formats (A = letter and 9 = digit):
AA9A 9AA AA9A9AA AA9A9AA
A9A 9AA Removing space A9A9AA order it AA999AA
A9 9AA ------------------> A99AA -------------> AA99AA
A99 9AA A999AA A9A9AA
AA9 9AA AA99AA A999AA
AA99 9AA AA999AA A99AA
As we can see, the length may vary from 5 to 7 and we have to take in account some special cases if we want to.
So the function we are coding has to do the following:
Remove spaces and convert to uppercase (or lower case).
Check if the input is an exception, if it is it should return valid
Check if the input's length is 4 < length < 8.
Check if it's a valid postcode.
The last part is tricky, but we will split it in 3 sections by length for some overview:
Length = 7: AA9A9AA and AA999AA
Length = 6: AA99AA, A9A9AA and A999AA
Length = 5: A99AA
For this we will be using a switch(). From now on it's just a matter of checking character by character if it's a letter or a number on the right place.
So let's take a look at our PHP implementation:
function check_uk_postcode($string){
// Start config
$valid_return_value = 'valid';
$invalid_return_value = 'invalid';
$exceptions = array('BS981TL', 'BX11LT', 'BX21LB', 'BX32BB', 'BX55AT', 'CF101BH', 'CF991NA', 'DE993GG', 'DH981BT', 'DH991NS', 'E161XL', 'E202AQ', 'E202BB', 'E202ST', 'E203BS', 'E203EL', 'E203ET', 'E203HB', 'E203HY', 'E981SN', 'E981ST', 'E981TT', 'EC2N2DB', 'EC4Y0HQ', 'EH991SP', 'G581SB', 'GIR0AA', 'IV212LR', 'L304GB', 'LS981FD', 'N19GU', 'N811ER', 'NG801EH', 'NG801LH', 'NG801RH', 'NG801TH', 'SE18UJ', 'SN381NW', 'SW1A0AA', 'SW1A0PW', 'SW1A1AA', 'SW1A2AA', 'SW1P3EU', 'SW1W0DT', 'TW89GS', 'W1A1AA', 'W1D4FA', 'W1N4DJ');
// Add Overseas territories ?
array_push($exceptions, 'AI-2640', 'ASCN1ZZ', 'STHL1ZZ', 'TDCU1ZZ', 'BBND1ZZ', 'BIQQ1ZZ', 'FIQQ1ZZ', 'GX111AA', 'PCRN1ZZ', 'SIQQ1ZZ', 'TKCA1ZZ');
// End config
$string = strtoupper(preg_replace('/\s/', '', $string)); // Remove the spaces and convert to uppercase.
$exceptions = array_flip($exceptions);
if(isset($exceptions[$string])){return $valid_return_value;} // Check for valid exception
$length = strlen($string);
if($length < 5 || $length > 7){return $invalid_return_value;} // Check for invalid length
$letters = array_flip(range('A', 'Z')); // An array of letters as keys
$numbers = array_flip(range(0, 9)); // An array of numbers as keys
switch($length){
case 7:
if(!isset($letters[$string[0]], $letters[$string[1]], $numbers[$string[2]], $numbers[$string[4]], $letters[$string[5]], $letters[$string[6]])){break;}
if(isset($letters[$string[3]]) || isset($numbers[$string[3]])){
return $valid_return_value;
}
break;
case 6:
if(!isset($letters[$string[0]], $numbers[$string[3]], $letters[$string[4]], $letters[$string[5]])){break;}
if(isset($letters[$string[1]], $numbers[$string[2]]) || isset($numbers[$string[1]], $letters[$string[2]]) || isset($numbers[$string[1]], $numbers[$string[2]])){
return $valid_return_value;
}
break;
case 5:
if(isset($letters[$string[0]], $numbers[$string[1]], $numbers[$string[2]], $letters[$string[3]], $letters[$string[4]])){
return $valid_return_value;
}
break;
}
return $invalid_return_value;
}
Note that I've not added British Forces Post Office and non-geographic codes.
Usage:
echo check_uk_postcode('AE3A 6AR').'<br>'; // valid
echo check_uk_postcode('Z9 9BA').'<br>'; // valid
echo check_uk_postcode('AE3A6AR').'<br>'; // valid
echo check_uk_postcode('EE34 6FR').'<br>'; // valid
echo check_uk_postcode('A23A 7AR').'<br>'; // invalid
echo check_uk_postcode('A23A 7AR').'<br>'; // invalid
echo check_uk_postcode('WA3334E').'<br>'; // invalid
echo check_uk_postcode('A2 AAR').'<br>'; // invalid

As supplied by the UK government.
(GIR 0AA)|((([A-Z-[QVX]][0-9][0-9]?)|(([A-Z-[QVX]][A-Z-[IJZ]][0-9][0-9]?)|(([A-Z-[QVX]][0-9][A-HJKSTUW])|([A-Z-[QVX]][A-Z-[IJZ]][0-9][ABEHMNPRVWXY])))) [0-9][A-Z-[CIKMOV]]{2})
I've built London only postcode based apps using the postcodes I got from HERE. But to be honest, even with London postcodes only, you need a lot more storage than necessary. Sure, the idea is trivial.
Store the postcodes, take the user input or whatever, and see if you get a match. But you are complicating the solution far more than you think. I HAD to use actual postcodes to achieve what I wanted, but for simple validation purposes, as hard as "maintaining" a regex is, storing tens of thousands or hundreds of thousands(if not more) and validating more or less in real-time is a far more difficult task.
If a mini distributed service sounds like a more efficient solution than a regex, go for it, but I'm sure it isn't. Unless you need geo-spatial querying of your own data against UK postcodes or things like that, I doubt DB storage is a feasible solution. Just my 2 cents.
Update
According to this index, there are 1,758,417 postcodes in the UK. I can tell you I am using a few Mongo clusters (Amazon EC2 High Memory Instances) to provide reliable London only services(indexing only London postcodes), and it's quite a pricy thing, even with basic storage.
Admittedly, the app is performing medium complexity geo-spatial queries, but the storage requirements alone are very expensive and demanding.
Bottom line, just stick to regex and be done with it in two minutes.

Im looking at the Postcodes in United Kingdom link in wikipedia right now.
http://en.wikipedia.org/wiki/Postcodes_in_the_United_Kingdom
The Validation section lists six formats with a combination of letters and numbers. Then there's more information in the notes below that. The first thing that I would try is a BNF type grammar with a tool like GoldParserBuilder. You could describe the basic formats in a more readable format, with efficient parser and lexer automatically generated. In the past, I've successfully used such tools to avoid writing huge, ugly regexes.
From that point, the program has a properly formatted zip code of a known type. At this point, the specific numbers or letters might violate something. Each type of zip code can have a function programmed to look for violations of that specific type. The final product will consist of an automatically generated parser that passes unvalidated, but structured/identified, zip codes to a dedicated validation function. You can then refactor or optimize from there.
(You can also use the grammar itself to enforce or disallow certain literals and combinations. Whatever is more readable or comprehensible for you. Different people gravitate toward different ends of these things.)
Here's a page highlighting advantages of GOLD Parsing System.You can use any you like: I just promote this one b/c it's good at its job and has steadily improved over many years.
http://www.goldparser.org/about/why-use-gold.htm

I would think the RegEX, while long-winded would probably be the best solution if all you want to do is validate if something could be a valid UK post code.
If you need absolute data, consider using Ordnance Survey OpenData initiative "Code-Point® Open" dataset, which is a CSV of lots of data points in Great Britain (so not Northern Ireland I'm guessing) one of which is postcode. Be aware that the file is 20MB, so you may have to convert it to a more manageable format.

Regexes are hard to debug, hard to port from one regex flavor to another (silent "errors"), and hard to update.
That is true for most regexes, but why don't you just split it up into multiple parts? You can easily split it into six parts for the six different general rules and maybe even more if you take all of the special cases into account.
Creating a well-commented method of 20 lines with simple regexes is easy to debug (one simple regex per line) and also easy to update. The porting problem is the same, but on the other hand you do not need to use some fancy grammar lib.

Are third party services an option?
http://www.postcodeanywhere.co.uk/address-validation/
GeoNames Database:
http://www.geonames.org/postal-codes/

+1 for the "why care" comments. I have had to use the 'official' regex in various projects and while I have never attempted to break it down, it works and it does the job. I've used it with Java and PHP code without any need to convert it between regex formats.
Is there a reason why you would have to debug it or break it down?
Incidentally, the regex rule used to be found on wikipedia, but it appears to have gone.
Edit: As for the space/no-space debate, the postcode should be valid with or without the space. As the last part of the postcode (after the space) is ALWAYS three digits, it is possible to insert the space manually, which will then allow you to run it through the regex rule.

Take the list of valid postcodes and check if the one entered is in it.

Related

Display word endings depend on gender (Polish language issue), PHP

This problem might not occure in English, but does really hurt in Polish language. I guess that my question is mostly for Polish users since they might already have a decent solution.
What I mean, is that the verbs in Polish language, are different for male and female in past time. And there are dozens of different options. If my script need to display lots and lots of text - it really becomes a painful problem to deal with. Short example (not very elegant use of language, but for demonstration purpose):
Male: On poszedł i nie znalazł, więc klasnął w dłonie i nagle go coś pożarło.
Female: Ona poszła i nie znalazła, więc klasnęła w dłonie i nagle ją coś pożarło.
I managed to find such an solution: each time at the beginning of script, I prepare variable that looks like that:
$verb[$ending][$sex] = 'something';
//$ending does contain - for my convenience - letters that says what kind of eding am I changing, instead of numeric options
//Examples:
$verb['-a']['male'] = '';
$verb['-a']['female'] = 'a';
//works for On=>Ona, znalazł=>znalazła
$verb['al-ela']['male'] = 'ął';
$verb['al-ela']['female'] = 'ęła';
//works for klasnął=>klasnęła
Now if I add fact, that 99% of time I don't know from the beginning what kind of sex am I dealing with, my variable start look kinda scary: $verb['al-ela'][$_SESSION['user'.$id]['sex']]. So my end text does look like that:
O'.$verb['-a'][$_SESSION['user'.$id]['sex']].' posz'.$verb['edl-la'][$_SESSION['user'.$id]['sex']].' i nie znalazł'.$verb['-a'][$_SESSION['user'.$id]['sex']].', więc klasn'.$verb['al-ela'][$_SESSION['user'.$id]['sex']].' w dłonie i nagle '.$verb['go-ja'][$_SESSION['user'.$id]['sex']].' coś pożarło.
Yes, sure - this is rather extreme example, but sometimes text really does look like that and it is unavoidable.
To make long story short, here are my questions:
Am I doing it wrong? Is there a better/faster/more handy solution for such type of problems?
Is there a script that might detect/change endings for me without ruining rest of the text?
I struggled to find full list of possible ending variations in Polish (for both singular, and plural), so I'm creating my own list as I'm finding new options. Perhaps someone does have a list like that => it might help me to create script from my 2nd question.
Thanks a lot in advance, best regards!

Coordinates: convert from WGS84 to a *specific* UTM-region

There are a lot of free tools out there to convert from UTM to Lat/Long. Fine enough, but I need to go the other way; from WGS-84 to lat/long-format.
But it's more complicated than that; 'couse I need the result to be in UTM-33 (nordic) zone.
This might sound like a bad idea; why would I like to "force" the zone to 33N, when the geographical point might be laying in another zone ...
Well; the thing is that I already have a database with UTM33-coordinates of every address in Norway.
Those of you that are familiar with UTM # Northern Europe, knows that Norway spans across several zones; from 31 to 36.
(Okay, maybe we only spans from 32 to 36, cause of the strange width of zone 32V, but thats another discussion).
So, back to my problem: all my addresses are already given in UTM-33 format (with negative values when out of range). How can i proceed to get my Lat/Long into UTM-33?
I need a solution in PHP, and after a lot of debugging with "gPoint", I found out it just won't work ...
(gPoint is great to convert from/to UTM, but it will always return the UTM x/y-pair in the "correct" zone block. I don't want that! I need to always get results in zone 33, regardless of what is actual correct..)
I finally found a solution though Proj4 (thanx SlightlyCuban)!
// Conversion from WGS84 to UTM33
$proj4 = new Proj4php();
$projWGS84 = new Proj4phpProj('EPSG:4326');
$projUTM33N = new Proj4phpProj('EPSG:2078');
$result = $proj4->transform($projWGS84, $projUTM33N, new proj4phpPoint($long, $lat));
It is impossible to guess correct format for transformation, and I was struggling for a while ... then I discovered a really handy webpage: http://spatialreference.org. Here I found the definition I needed (EPSG:2078 = "+proj=utm +zone=33 +ellps=intl +units=m +no_defs")
The PHP-implementation of Proj4 needs hard-coded definitions; you cannot pass by a definition ad-hoc. EPSG:2078 was originally missing from Proj4php. Yay; lucky me!
I would therefor recommend to test Proj4 via Node.js and proj4js (see my little demo at http://pastebin.com/1BP8cWpj).
To succeed, I had to fork the Proj4PHP-library, and add a definition file for EPSG:2078 ...

PHP preg_replace markdown issue - detecting duplicates

In a project I am building I would like to use markdown as follows
*text* = <em>text</em>
**text** = <strong>text</strong>
***text*** = <strong><em>text</em><strong>
As those are the only three markdown formats I require, I would like to remain lightweight and avoid importing the entire PHP markdown library as that would introduce features I do not require and create issues.
So I have been trying to build some simple regex replaces. Using preg_replace I run:
'/(\*\*\*)(.*?)\1/' to '<strong><em>\2</em></strong>'
'/(\*\*)(.*?)\1/' to '<strong>\2</strong>'
'/(\*)(.*?)\1/' to '<em>\2</em>',
And this works great! em, bold, and the combo all work fine...
But if the user makes a mistake or enters to many stars, everything breaks.
i.e.
****hello**** = <strong><em><em>hello</em></strong></em>
*****hello***** = <strong><em><strong>hello</em></strong></strong>
******hello****** = <strong><em></em></strong>hello<strong><em></em></strong>
etc
When ideally it would create
****hello**** = *<strong><em>hello</em></strong>*
*****hello***** = **<strong><em>hello</em></strong>**
******hello****** = ***<strong><em>hello</em></strong>***
etc
Ignoring the un-required stars (so it would become clear to the user they made a mistake, and more importantly, the rendered HTML remains valid).
I presume there must be some way to modify my regex to do this but I cannot for the life of my work it out, even after a whole day trying!
I would also be happy with the result of
******hello****** = <strong><em>hello</em></strong>
So please, can anybody help me?
Also please consider uneven stars. In this case the below scenario would be ideal.
***hello* = **<em>hello</em>
And the time when a star should be part of the body and not detected, such as if a user inputs:
'terms and conditions may apply*'
or
'I give the film 5* out of 10'
Many many thanks
Try different capturing pattern (match anything except * one or more times),
'/(\*\*\*)([^*]+)\1/'

User Friendly, Easy to Remember Coupon Codes

I want to create coupon codes that users can remember easily. My idea is something like:
squirrel45
nantucket23
That is, a real word chosen randomly from a long dictionary list (preferably compiled for this purpose) combined 2 random digits. My questions are:
Where can I find such a dictionary list?
Do you see any problems with the system? (security is not ultra important here, just something reasonable is fine)
Can you suggest any good improvements or alternatives?
Fwiw I am not crazy about the Markov word generators because I think their idiosyncrasies would be too hard to remember. I'd like a client to be able to keep the code in his head, and tell it to the merchant when he arrives to redeem it.
Thanks,
Jonah
Word lists are easy to find. Make sure you sanity filter them for foul words ;)
Here's a huge word list that can be easily scrubbed:
http://www.scrabble-assoc.com/boards/dictionary/10-15-20030401.txt
From there you can easily load in words into your database and create your coupon code like so:
$coupon_code = $rand_word . rand(20,99);
After you do this, simply store your coupon code in the database and whenever you make a new code, check it against existing codes before you apply it. Even slim odds are possible odds.
More word lists in various formats:
http://scrabble.wonderhowto.com/blog/ultimate-scrabble-word-list-resource-0115617/
5-letter words:
http://homepage.ntlworld.com/adam.bozon/Scrabble5.htm
6-letter words:
http://homepage.ntlworld.com/adam.bozon/Scrabble6.htm
7-letter words:
http://homepage.ntlworld.com/adam.bozon/Scrabble7.htm
8-letter words:
http://homepage.ntlworld.com/adam.bozon/Scrabble8.htm
Sample:
PIKES PIKIS PILAF PILAR PILAU PILAW PILEA PILED PILEI PILES PILIS
PILLS PILOT PILUS PIMAS PIMPS PINAS PINCH PINED PINES PINEY PINGO
PINGS PINKO PINKS PINKY PINNA PINNY PINON PINOT PINTA PINTO PINTS
PINUP PIONS PIOUS PIPAL PIPED PIPER PIPES PIPET PIPIT PIQUE PIRNS
PIROG PISCO PISOS PISTE PITAS PITCH PITHS PITHY PITON PIVOT PIXEL
PIXES PIXIE PIZZA PLACE PLACK PLAGE PLAID PLAIN PLAIT PLANE PLANK
PLANS PLANT PLASH PLASM PLATE PLATS PLATY PLAYA PLAYS PLAZA PLEAD
PLEAS PLEAT PLEBE PLEBS PLENA PLEWS PLICA PLIED PLIER PLIES PLINK
PLODS PLONK PLOPS PLOTS PLOTZ PLOWS PLOYS PLUCK PLUGS PLUMB PLUME
PLUMP PLUMS PLUMY PLUNK PLUSH PLYER POACH POCKS POCKY PODGY PODIA
POEMS POESY POETS POGEY POILU POIND POINT POISE POKED POKER POKES
With that you could generate a coupon code POACH72
Concatenating 2 words will increase the security posture of your system.
e.g. squirrel.nantucket.123
The Diceware page has a couple of long word lists, American and International. It also has a useful description of how to meet various levels of security.

Using regex to extract variables from a plain-text form letter?

I'm looking for a good example of using Regular Expressions in PHP to "reverse engineer" a form letter (with a known format, of course) that has been pasted into a multiline textbox and sent to a script for processing.
So, for example, let's assume this is the original plain-text input (taken from a USDA press release):
WASHINGTON, April 5, 2010 - North
American Bison Co-Op, a New Rockford,
N.D., establishment is recalling
approximately 25,000 pounds of whole
beef heads containing tongues that may
not have had the tonsils completely
removed, which is not compliant with
regulations that require the removal
of tonsils from cattle of all ages,
the U.S. Department of Agriculture's
Food Safety and Inspection Service
(FSIS) announced today.
For clarity, the fields that are variables are highlighted below:
[pr_city=]WASHINGTON, [pr_date=]April 5, 2010 - [corp_name=]North
American Bison Co-Op, a [corp_city=]New Rockford,
[corp_state=]N.D., establishment is recalling
approximately [amount=]25,000 pounds of [product=]whole
beef heads containing tongues that may
not have had the tonsils completely
removed, which is not compliant with
regulations that require [reason=]the removal
of tonsils from cattle of all ages,
the U.S. Department of Agriculture's
Food Safety and Inspection Service
(FSIS) announced today.
How could I efficiently extract the contents of the
pr_city
pr_date
corp_name
corp_city
corp_state
amount
product
reason
fields from my example?
Any help would be appreciated, thanks.
Well, a regex that works on your example could look like this (line breaks introduced to keep this beast legible, need to be removed prior to use):
/^(?P<pr_city>[^,]+), (?P<pr_date>[^-]+) - (?P<corp_name>.*?), a
(?P<corp_city>[^,]+), (?P<corp_state>[^,]+), establishment is
recalling approximately (?P<amount>.*?) of (?P<product>.*?),
which is not compliant with regulations that require (?P<reason>.*?),
the U\.S\. Department of Agriculture\'s Food Safety and Inspection
Service \(FSIS\) announced today\.$/
So, in PHP you could do
if (preg_match('/^(?P<pr_city>[^,]+), (?P<pr_date>[^-]+) - (?P<corp_name>.*?), a (?P<corp_city>[^,]+), (?P<corp_state>[^,]+), establishment is recalling approximately (?P<amount>.*?) of (?P<product>.*?), which is not compliant with regulations that require (?P<reason>.*?), the U\.S\. Department of Agriculture\'s Food Safety and Inspection Service \(FSIS\) announced today\.$/', $subject, $regs)) {
$prcity = $regs['pr_city'];
$prdate = $regs['pr_date'];
... etc.
} else {
$result = "";
}
This assumes a couple of things, for instance that there are no line breaks, and that the input is the entire string (and not a larger string from which this part has to be extracted from). I've tried to make assumptions about legal values that make some sense, but there is the very real chance that other inputs could break this. So some more test cases are probably needed.
If the surrounding text is constant, then something like this partial regex could do the trick:
preg_match('/^(.*?), (.*?)- (.*?), a (.*?), (.*?), establishment is recalling approximately (.*?), which is not compliant with regulations that require (.*?), the U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS) announced today./', $text, $matches);
$matches[1] = 'WASHINGTON';
$matches[2] = 'April 5, 2010';
$matches[3] = ... etc...
If the surrounding text changes, then you're going to end up with a ton of false matches, no matches, etc... Essentially you'd need an AI to parse/understand PR releases.
Edit: Please disregard this crazy answer, as the other two are better. I should probably delete it, but I'm keeping it up for reference.
I have a crazy idea that just might work: build an XML string from the input by adding markups, then parse it. It might look something like this (completely untested) code:
preg_replace('([^,]*), ([^-]*)- ...etc...', '<pr_city>\1</pr_city><pr_date>\2</pr_date> ...etc...');
Parsing the XML afterwards is a needlessly complicated process that is best left to the PHP documentation: http://www.php.net/manual/en/function.xml-parse.php .
You could also consider converting it to JSON with this method, then using json_decode() to parse it. In any case, you have to think about what happens when " marks and > symbols appear in the input.
It might be easier to just match and remove one piece of the text at a time.

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