Regex for Username?

Question

I am using C# and jQuery to valid a username with Regex. Just learning :) So far I have

UserName = "[a-zA-Z0-9]";

But this doesn't stop symbols ? How to ensure that no symbols or " . " or " _ " ?

Thanks

Answer 1

That regex says "At least one letter or number" you want "Every character from the start to the end is a letter or number"

"^[a-zA-Z0-9]+$"