CODEWITHSUNDEEP
regex
codymanix
codymanix

Reputation: 29468

Regular Expression for testing length of string part

Hi I need a regular expression which is accepting the following strings:

[A-Z]-[A-Z]{3-5}[0-9]{2-4}

for example X-ABC123 or Y-AB1234

The problem now is that the total length of the string on the right side of the hyphen must always be 5 chars in length. Is there a chance to check that with regular expressions only?

Upvotes: 0

Views: 230

Answers (3)

FailedDev
FailedDev

Reputation: 26930

Just add this after the hyphen : 

/(?=[A-Z\d]{5}$)/

Resulting in : 

/^[A-Z]-(?=[A-Z\d]{5}$)[A-Z]{3,5}[0-9]{2,4}/

This assumes that your input strings are the strings you posted.

X-ABC123 -> fails
Y-AB1234 -> fails
A-ABD12  -> matches
A-ABV111 -> fails

If the string is part of another string you can replace the $ anchor with \s|$ for example.

Upvotes: 1

BuZz
BuZz

Reputation: 17445

I think it's definitely possible, from a language theory point of view. Just group it and add the constraint :

I just need to know which language is specifying the regex but something like this :

[A-Z]-(^[A-Z][A-Z0-9]4)

I had the feeling you wanted the right part to start with one char for sure, then either chars or numbers

Upvotes: 0

stema
stema

Reputation: 92976

First the problems in your regex

The quantifier is {3,5} and not {3-5} (this would match literally "{3-5}")

You want 3 to 5 letters and 2 to 4 digits and in total 5 letters and digits ==> the only valid combination is then 3 letters followed by 2 digits.

In general you can use a positive lookahead for this

^[A-Z]-(?=.{5}$)[A-Z]{3,5}[0-9]{2,4}$

See it here on Regexr

The (?=.{5}$) part is just looking, if there are from its position to the end ($) 5 characters.

But as said before, if the 3-5 and 2-4 and overall 5 is valid you can just do

^[A-Z]-[A-Z]{3}[0-9]{2}$

Upvotes: 0

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