Case insensitive UK postcode regex

Question

I have the following regular expression for matching UK postcodes:

GIR[ ]?0AA|((AB|AL|B|BA|BB|BD|BH|BL|BN|BR|BS|BT|CA|CB|CF|CH|CM|CO|CR|CT|CV|CW|DA|DD|DE|DG|DH|DL|DN|DT|DY|E|EC|EH|EN|EX|FK|FY|G|GL|GY|GU|HA|HD|HG|HP|HR|HS|HU|HX|IG|IM|IP|IV|JE|KA|KT|KW|KY|L|LA|LD|LE|LL|LN|LS|LU|M|ME|MK|ML|N|NE|NG|NN|NP|NR|NW|OL|OX|PA|PE|PH|PL|PO|PR|RG|RH|RM|S|SA|SE|SG|SK|SL|SM|SN|SO|SP|SR|SS|ST|SW|SY|TA|TD|TF|TN|TQ|TR|TS|TW|UB|W|WA|WC|WD|WF|WN|WR|WS|WV|YO|ZE)(\d[\dA-Z]?[ ]?\d[ABD-HJLN-UW-Z]{2}))|BFPO[ ]?\d{1,4}/gi

From what I understand I can add /gi to the end to make it match case insensitive however this doesn't seem to work at all? Can anyone see why?

What is your regex engine? Depending on which one you're using, using `/gi` might not work and instead `(?i)` at the start of the expression will make the expression case insensitive. — Jerry, Jul 03 '13 at 15:31
@Jerry .NET, this regex is fed to a `RegularExpressionValidator` control on an Asp.net page — dtsg, Jul 03 '13 at 15:32
You shouldn't need to add `g` - only `i` - but when you say "doesn't seem to work", what do you mean? — Aleks G, Jul 03 '13 at 15:33
@AleksG `when you say "doesn't seem to work", what do you mean?` I mean it doesn't match UK postcodes when entered lower case. Uppercase is fine — dtsg, Jul 03 '13 at 15:33
possible duplicate of [Make regular expression case insensitive in ASP.NET RegularExpressionValidator](http://stackoverflow.com/questions/2641236/make-regular-expression-case-insensitive-in-asp-net-regularexpressionvalidator) — cb0, Jul 03 '13 at 15:34
See [this answer](http://stackoverflow.com/a/2641246/1578604). — Jerry, Jul 03 '13 at 15:34
@Jerry Initial testing with `(?i)` at the start of the expression seems to work flawlessly. I would add this as the answer — dtsg, Jul 03 '13 at 15:36
I know that I can use `RegexOptions.IgnoreCase` however the system I'm building reads in different regexs per country where some actually require case sensitivity which would mean I would have to code specific logic to handle UK postcodes whereas I would prefer this all to be handled by the expression itself — dtsg, Jul 03 '13 at 15:42

score 3 · Answer 1 · edited May 23 '17 at 12:22

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Just uppercase your postcode string before putting it through your regex.
Also have a look at this question on UK postcodes

edited May 23 '17 at 12:22

Community

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answered Jul 03 '13 at 15:34

zeFrenchy

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score 2 · Answer 2 · answered Jul 03 '13 at 15:34

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If you're using .Net perhaps use RegexOptions.IgnoreCase when you construct? Taken from here.

That page also has a link to this expression which might be worth trying.

answered Jul 03 '13 at 15:34

Nick

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I'd rather handle this via the expression itself but thanks all the same – dtsg Jul 03 '13 at 15:35

score 2 · Accepted Answer · answered Jul 03 '13 at 16:21

Depending on which one you're using, using /gi might not work and instead (?i) at the start of the expression will make the expression case insensitive.

So, you'd use:

(?i)GIR[ ]?0AA|((AB|AL|B|BA|BB|BD|BH|BL|BN|BR|BS|BT|CA|CB|CF|CH|CM|CO|CR|CT|CV|CW|DA|DD|DE|DG|DH|DL|DN|DT|DY|E|EC|EH|EN|EX|FK|FY|G|GL|GY|GU|HA|HD|HG|HP|HR|HS|HU|HX|IG|IM|IP|IV|JE|KA|KT|KW|KY|L|LA|LD|LE|LL|LN|LS|LU|M|ME|MK|ML|N|NE|NG|NN|NP|NR|NW|OL|OX|PA|PE|PH|PL|PO|PR|RG|RH|RM|S|SA|SE|SG|SK|SL|SM|SN|SO|SP|SR|SS|ST|SW|SY|TA|TD|TF|TN|TQ|TR|TS|TW|UB|W|WA|WC|WD|WF|WN|WR|WS|WV|YO|ZE)(\d[\dA-Z]?[ ]?\d[ABD-HJLN-UW-Z]{2}))|BFPO[ ]?\d{1,4}

Case insensitive UK postcode regex

3 Answers3