You could use a regular expression: add
using System.Text.RegularExpressions;
to the top of your code file, and in your method:
if (Regex.IsMatch(Alias, "[0-9]"))
{
return false;
}
[0-9]
is a
regular expression[
^] that means "a number from 0 to 9". Regex.IsMatch checks if 'Alias' matches that and if it does, your method returns false. So, it will return false for "hello 1", "hello 2", "hello 12345" and everything else that contains a number.