Problem statement

A new gaming platform requires strict username creation. A valid username must not contain any spaces, @ symbols, or # symbols. You must build a validator that ensures a requested username adheres to these strict rules from start to finish.

Task requirements

• Accept a string representing the requested username.

• Validate the username using a regular expression.

• Return true if the username consists only of permitted characters.

• Return false if the username contains any forbidden characters (spaces, @, or #) or if it is completely empty.

Constraints

• Use the static Regex.IsMatch() method to evaluate the string.

• Use the ^ and $ anchors to ensure your pattern applies to the entire string.

• Use a negated character class [^...] to define the forbidden characters.

• Use the + quantifier to ensure the username has at least one valid character.

Good luck trying the exercise! If you’re unsure how to proceed, check the “Solution” tab above.

Get hints

• Look at the email validation example from the lesson. The [^@\s] syntax means not an @ and not a whitespace character.

• You can add the # character to that negated set to forbid it as well.

• Do not forget the + operator so the regular expression engine knows it must match one or more of the valid characters.