Regular expression to match exact number of characters?


I need a regular expression that will match any three uppercase letters, so AAA or ABC or DKE. It can't match four or more though, like AAAA or ABCDEF or aBBB.

My solution: ^([A-Z][A-Z][A-Z])$


  1. Is this correct?
  2. Is there another way, just for the sake of learning?

This question is tagged with regex

~ Asked on 2013-01-29 18:46:37

The Best Answer is


What you have is correct, but this is more consice:


~ Answered on 2013-01-29 18:47:09


Your solution is correct, but there is some redundancy in your regex.
The similar result can also be obtained from the following regex:


The {3} indicates that the [A-Z] must appear exactly 3 times.

~ Answered on 2013-01-29 18:51:41

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