How can I get a regex to check that a string only contains alpha characters [a-z] or [A-Z]?

Question

I\'m trying to create a regex to verify that a given string only has alpha characters a-z or A-Z. The string can be up to 25 letters long. (I\'m not sure if regex can check

Answer 1

The regular expression you are using is an alternation of [^a-z] and [^A-Z]. And the expressions [^…] mean to match any character other than those described in the character set.

So overall your expression means to match either any single character other than a-z or other than A-Z.

But you rather need a regular expression that matches a-zA-Z only:

[a-zA-Z]

And to specify the length of that, anchor the expression with the start (^) and end ($) of the string and describe the length with the {n,m} quantifier, meaning at least n but not more than m repetitions:

^[a-zA-Z]{0,25}$