C# 取中间文本最实用的代码

/// <summary>
        /// 取中间文本
        /// </summary>
        /// <param name="str">全文本</param>
        /// <param name="str1">前文本</param>
        /// <param name="str2">后文本</param>
        /// <returns></returns>
        public static string 取中间文本(string str, string str1, string str2)
        {
            int i1 = str.IndexOf(str1);
            int i2 = -1;
            string strok = "";
            if (i1 != -1)
            {
                i2 = str.IndexOf(str2, i1);
            }
            if (i2 != -1)
            {
                strok = str.Substring(i1 + 1, i2 - i1 - 1);
            }
            return strok;
        }