Windows Batch File Regular Expression

Question

I have a following requirement that needs to be achieved in .bat file. Can some one please help.

There is a string, ABCD-1234 TEST SENTENCE in a variable, say str. Now I want to check if the string starts with format [A-Z]*-[0-9] * or not.

How can I achieve this? I tried various regular expression using FINDSTR, but couldn't get the desired result.

Example:

set str=ABCD-1234 TEST SENTENCE
echo %str% | findstr /r "^[A-Z]*-[0-9] *"

It does work. C:\Windows\system32>echo ABCD-1234 TEST SENTENCE | findstr /r "^[A-Z]*-[0-9] *" which shows ABCD-1234 TEST SENTENCE showing it matched. — user6017774
– user6017774, Commented Jan 4, 2017 at 4:32
FINDSTR regex capabilities are totally non-standard (and crippled). Describe exactly what search criteria you want, and give examples of strings that should match, as well as strings that should not. — dbenham
– dbenham, Commented Jan 4, 2017 at 4:37

Community · Accepted Answer · 2017-05-23 12:24:37Z

2

I'm assuming you are looking for strings that begin with 1 or more upper case letters, followed by a dash, followed by 1 or more digits, followed by a space.

If the string might contain poison characters like &, <, > etc., then you really should use delayed expansion.

FINDSTR regex is totally non-standard. For example, [A-Z] does not properly represent uppercase letters to FINDSTR, it also includes most of the lowercase letters, as well as some non-English characters. You must explicitly list all uppercase letters. The same is true for the numbers.

A space is interpreted as a search string delimiter unless the /C:"search" option is used.

setlocal enableDelayedExpansion
echo(!str!|findstr /rc:"^[ABCDEFGHIJKLMNOPQRSTUVWXYZ][ABCDEFGHIJKLMNOPQRSTUVWXYZ]*-[0123456789][0123456789]* "

You should have a look at What are the undocumented features and limitations of the Windows FINDSTR command?

edited May 23, 2017 at 12:24

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answered Jan 4, 2017 at 4:46

dbenham

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3 Comments

aschipfl Over a year ago

Why is it necessary to state [0123456789] rather than [0-9]? I could not find any wrong (mis-)matches. I am aware of the [A-Z] flaw...

dbenham Over a year ago

@aschipfl - From a practical standpoint, it is probably not necessary. But there are a few extended ASCII characters that lie within the range [0-9]. I believe they represent things like 1/2, 1/4, etc. So a precise solution does require [0123456789].

dbenham Over a year ago

@aschipfl - You could use [0123-9] and still be precise, but it is not something I remember, so I just list all the digits. The [0-3] term is equivalent to [0¼½12²3].

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