Regex To Validate A Letter Range With Repeats

Question

I would like to validate a string for letters A-Z, AA-ZZ, AAA-ZZZ, and so on with a regex. I know [A-Z] will validate the first case but what about the others.

A, B, C, D, E, .... Z

or

AA, BB, CC, DD, EE, .... ZZ

or

AAA, BBB, CCC, DDD, EEE, ... ZZZ

and so on...

Answer 1

This is a pain to write, but if you want to match any number of letters and require them to all be the same letter, you could use something like this:

^(A+|B+|C+|D+ ...)$

and so on through the rest of the alphabet.

Answer 2

Try

^(\w)\1*$

You match any word character. If it is more than one char, it has to be the same.