C# 截取字符串，区分中英文情况

 1 public static string SubstringByCN(string strInput, int begin, int length)
 2         {
 3             if (!Regex.IsMatch(strInput, "[u4E00-u9FA5uF900-uFA2D]", RegexOptions.IgnoreCase))
 4             {
 5                 if (strInput.Length < length)
 6                     return strInput;
 7                 else
 8                     return strInput.Substring(0, length);
 9             }
10             else
11             {
12                 string checkstr = Regex.Replace(strInput, "[u4E00-u9FA5uF900-uFA2D]", "**", RegexOptions.IgnoreCase);
13                 if (checkstr.Length < length)
14                     return strInput;
15                 else
16                 {
17                     string strOut = "";
18                     int strLength = 0;
19                     for (int i = 0; i < strInput.Length; i++)
20                     {
21                         if (strLength >= length)
22                             break;
23                         strOut += strInput.Substring(i, 1);
24                         if (!Regex.IsMatch(strInput.Substring(i, 1), "[u4E00-u9FA5uF900-uFA2D]", RegexOptions.IgnoreCase))
25                             strLength += 1;
26                         else
27                             strLength += 2;
28                     }
29                     return strOut;
30                 }
31             }
32         }