//ensure username is only a number or alphabetic letter, with at least 3 characters
public bool ValidateUsername(string username)
{
bool valid = false;
Regex reg = new Regex(@"^[a-zA-Z0-9]*$");
string phrase = TextBoxStyle.CheckWhichTextBox("username");
if (reg.IsMatch(username) && username != phrase && username.Length >= 3)
{
valid = true;
}
return(valid);
}