c# 去除字符串中的script脚本

        public string RemoveScript(string str)
        {
            str = str.ToLower();
            int length=str.Length;

            ArrayList arr1 = new ArrayList();
            ArrayList arr2 = new ArrayList();

            for (int i = 0; i < length - 6;i++ )
            {
                if (str[i].ToString() == "<")
                {
                    if (str[i + 1].ToString() == "s" && str[i + 2].ToString() == "c" && str[i + 3].ToString() == "r" &&
                        str[i + 4].ToString() == "i" && str[i + 5].ToString() == "p" && str[i + 6].ToString() == "t")
                    {
                        arr1.Add(i);
                        for (int j = i + 8; j < length - 6; j++)
                        {
                            if (str[j].ToString() == "<")
                            {
                                if (str[j + 1].ToString() == "/" && str[j + 2].ToString() == "s" && str[j + 3].ToString() == "c" && str[j + 4].ToString() == "r" &&
                                     str[j + 5].ToString() == "i" && str[j + 6].ToString() == "p" && str[j + 7].ToString() == "t")
                                {
                                    arr2.Add(j + 9);
                                    i = j + 9;
                                    break;
                                }
                            }
                        }//找邻近的"</script"位置
                    }
                }
            }//逐个查看“<script”的开始位置

            string NoscriptStr = "";
            if (arr1.Count==arr2.Count)
            {
                int arrlen = arr1.Count;
                int subleft = 0;
                int subright = 0;
                string substr = "";

                for (int k = 0; k < arrlen; k++)
                {
                    subright = Convert.ToInt32(arr1[k].ToString());
                    substr = str.Substring(subleft, subright - subleft);
                    NoscriptStr = NoscriptStr + substr;
                    subleft = Convert.ToInt32(arr2[k].ToString());
                }
                substr = str.Substring(subleft, length - subleft);
                NoscriptStr = NoscriptStr + substr;
            }

            return NoscriptStr;
        }