asq.net 去掉重复的数组

    string _str = string.Empty;
            string[] strArray = "12,14,25,32,32,25,25,11,23,15,48,11".Split(',');

            Int32 BuyCourseTypesSN_Count = 0;

            for (int i = 0; i < strArray.Length; i++)
            {
                for (int j = i + 1; j < strArray.Length; j++)
                {
                    if (strArray[j] == strArray[i])
                    {
                        strArray[i] = string.Empty;
                    }
                }
                if (strArray[i] != string.Empty)
                {
                    BuyCourseTypesSN_Count += 1;
                    _str += strArray[i] + ",";
                }
            }
            if (_str.LastIndexOf(",") > -1)
            {
                _str = _str.Substring(0, _str.Length - 1);
            }

            Response.Write(_str+"<br>");
            Response.Write(BuyCourseTypesSN_Count);

            this.Labl_BuyCourseTypesSN.Text = BuyCourseTypesSN_Count.ToString();