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st: problem with regexm leading to "regexp: unterminated ()" error for all observations

From   Jamie Fagg <>
To   Statalist <>
Subject   st: problem with regexm leading to "regexp: unterminated ()" error for all observations
Date   Fri, 03 Jun 2011 13:35:19 +0100

Dear Stata users,

I've a problem with the function -regexm-. I get the following message:

regexp: unterminated ()

Frederico Belotti raised this in 2009 ( and Martin Weiss suggested contacting Tech support but as far as I can see there is no other comment referring to the error.

My aim: to find out which of a list of 22,907 postcodes conform to the UK standard syntax.

I've never used regular expressions before, and I started trying to build the regular expression myself yesterday and ran a few options with some (limited) success before a colleague pointed me to a pre-written regular expression on Wikipedia ( As this seems highly complex, has been done, and I really only want to do this once, it would be very helpful to be able to simply use it within Stata.

I have run the regular expression through a javascript regular expression checker here ( and it seemed to work correctly, picking out the valid (E1 4NS, SW8 2XR)
versions of the postcodes in the example below.

This is an example of the code I used plus sample data if users want to see if they can reproduce the error.

I would very much appreciate any feedback about this,

Best wishes,


******start of example*********

input str15 postcode
E1 4NS

#delimit ;

//regular expression to define whether postcode is syntactically correct

ge postcodevalid = 1 if regexm(postcode,"(GIR 0AA)|(((A[BL]|B[ABDHLNRSTX]
[0-9])|EC[1-9][0-9]) [0-9][ABD-HJLNP-UW-Z]{2})")==1;

*****end of example*******

******My Stata specs********

Stata/SE 11.1 for Windows (32-bit)

Stata executable
folder: C:\Program Files\Stata11\
name of file: StataSE.exe
currently installed: 04 Nov 2010

Ado-file updates
folder: C:\Program Files\Stata11\ado\updates\
names of files: (various)
currently installed: 04 Jan 2011

Utilities updates
folder: C:\Program Files\Stata11\utilities
names of files: (various)
currently installed: 01 Sep 2010

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