Question

I’m using the ASP.NET RegularExpressionValidator

I need a regular expression to keep users who fill out a form from using all caps.

For example, if they write their name:

Bob JONES or BOB JONES or BOB JOnes or whatever, it will not match.

I am able to match all caps with this regular expression:

[A-Z]{2,10}

But the RegularExpressionValidator requires me to match valid text, not invalid text.

Answer 1

If your goal is to have each word have no more than 1 capital letter in a row at a time, and assuming it’s okay to restrict to ASCII letters, try something like this:

^(?:[a-z]|[A-Z](?![A-Z])|['-])+$

In other words, the string must be entirely composed of either lowercase letters, or uppercase letters not followed by another uppercase letter.

This works for single words. For multiple words (like a full name, first and last), simply add a space to the alternation:

^(?:[a-z]|[A-Z](?![A-Z])|[\s'-])+$

(Edited to allow apostrophe and hyphen punctuation)