[regex] 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 related to regex

The answer is

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


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