C# 半角？全角

/// <summary>
    /// 将资料表中已修改的资料行数据去左右空格、全角转半角
    /// </summary>
    public sealed class FieldFitString
    {
        const string _SEPERATOR = "&^*";

        /// <summary>
        /// 将资料表中已修改的资料行数据去左右空格、全角转半角
        /// </summary>
        /// <param name="dt"></param>
        public static void FitString(DataTable dt)
        {
            DataTable tmp = dt.GetChanges();
            if (tmp == null) return;

            //枚举Columns,仅处理字符类型的Field
            //枚举DataRow,仅处理新增、修改状态的记录
            string tmpFileNames = string.Empty;

            //取出字段
            for (int i = 0; i < dt.Columns.Count; i++)
            {
                if (dt.Columns[i].DataType == Type.GetType("System.String"))
                {
                    tmpFileNames += _SEPERATOR + dt.Columns[i].Caption;
                }
            }

            string[] FileNames = tmpFileNames.Split(new string[] { _SEPERATOR }, StringSplitOptions.RemoveEmptyEntries);

            //仅处理已修改的资料行
            foreach (DataRow dr in dt.Rows)
            {
                if (dr.RowState == DataRowState.Added || dr.RowState == DataRowState.Modified)
                {
                    foreach (string filename in FileNames)
                    {
                        dr[filename] = RemoveChar(ConvertEx.ToString(dr[filename]));
                    }
                }
            }
        }


        /// <summary>
        /// 将资料表中已修改的资料行数据去左右空格、全角转半角
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        public static string RemoveChar(string str)
        {
            if (String.IsNullOrEmpty(str)) return str;

            try
            {
                string NewStr = string.Empty;
                char[] c = str.ToCharArray();
                for (int i = 0; i < c.Length; i++)
                {
                    byte[] b = System.Text.Encoding.Unicode.GetBytes(c, i, 1);


                    if (b.Length == 2)
                    {
                        //全角
                        if (b[1] == 255 || b[1] == 48)
                        {
                            b[0] = (byte)(b[0] + 32);
                            b[1] = 0;
                            NewStr += System.Text.Encoding.Unicode.GetChars(b)[0];
                        }
                        else
                        {
                            NewStr += c[i];
                        }
                    }
                }

                return NewStr.Trim();//去左右空格

            }
            catch
            {
                return str;
            }
        }

    }