Regex to check if the first character is uppercase

Question

I\'m trying to check that the first character of a username is capital, the following can be letters or numbers and at most 20 characters long. Can someone explain why my synta

Answer 1

Your first character needs to be A-Z, not A-z

So

/^[A-z][a-z0-9_-]{3,19}$/

Should be

/^[A-Z][a-z0-9_-]{3,19}$/