C#正则检测字符串是否字母数字混编的方法

using System.Text;using System.Text.RegularExpressions;public static class StringExtensions{ public static bool IsAlphanumeric(this string source) {  Regex pattern = new Regex("[^0-9a-zA-Z]");  return !pattern.IsMatch(source); }}// EXAMPLE USAGEclass Program{ static void Main(string[] args) {  string testString = Console.ReadLine();  if (testString.IsAlphanumeric())   Console.WriteLine("Yep!");  else   Console.WriteLine("Nope!");  Console.ReadKey(); // Wait for key before exiting }}