提取字符串中的数字字符串

 1  /// <summary>
 2  /// 提取字符串中的数字字符串
 3 /// </summary>
 4  /// <param name="str"></param>
 5 /// <returns></returns>
 6  public static string IsNumber(String str)
 7  {
 8             string returnStr = string.Empty;
 9             for (int i = 0; i < str.Length; i++)
10             {
11                 if (Char.IsNumber(str, i) == true)
12                 {
13                     returnStr += str.Substring(i, 1);
14                 }
15                 else
16                 {
17                     if (str.Substring(i, 1) == "A" || str.Substring(i, 1) == " ")
18                     {
19                         returnStr += str.Substring(i, 1);
20                     }
21                 }
22 
23             }
24             return returnStr;
25 }