string a = "avdfd";
      try
      {
        int b = int.Parse(a);
      }
      catch (Exception)
      {
        Console.WriteLine("不是");
      }

bool IsNumber = int.TryParse("你要判斷的值",out int a);

Regex.IsMatch(input, @"^\d+$")

 string str = "甘霖娘233不要再說了";  //我們抓取當(dāng)前字符當(dāng)中的233
 string result = System.Text.RegularExpressions.Regex.Replace(str, @"[^0-9]+", "");3 Console.WriteLine(result);