C#验证是不是合法的18位身份证号码

验证是不是合法的18位身份证号码代码：

 1   public static bool IsValidIDNumber(string strId)
 2         {
 3             Regex regId = new Regex(@"^\d{17}(\d|x)$", RegexOptions.IgnoreCase);
 4             if (strId.Length != 18)
 5             {
 6                 return false;
 7             }
 8             else
 9             {
10                 if (!regId.IsMatch(strId))
11                 {
12                     return false;
13                 }
14                 else
15                 {
16                     int iS = 0;
17                     int[] iW = new int[] { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2 };
18                     string LastCode = "10X98765432";
19                     for (int i = 0; i < 17; i++)
20                     {
21                         iS += int.Parse(strId.Substring(i, 1)) * iW[i];
22                     }
23                     int iY = iS % 11;
24                     if (strId.Substring(17, 1) != LastCode.Substring(iY, 1))
25                         return false;
26                     return true;
27                 }
28             }
29         }