C#正则只充许输入字母数字空格逗号

        public static string CleanInput2(string strIn)
       {
            //字母[a-zA-Z] 数字[0-9] 空格[\s] 下划线[_] 合起来 ^[a-zA-Z0-9_\s]*$   \u4e00-\u9fa5表示允许输入汉字
            string pattern = @"[a-zA-Z0-9,-_\u4e00-\u9fa5\s]";
            string strRet = "";
            MatchCollection results = Regex.Matches(strIn, pattern);
            foreach (var v in results)
            {
                strRet += v.ToString();
            }
            return strRet;
       }