C# 统计N个相同子字符串的个数及位置

 using System.Text.RegularExpressions;
   
    /// <summary>
        /// 计算字符串中子串出现的次数
        /// </summary>
        /// <param name="str">字符串</param>
        /// <param name="substring">子串</param>
        /// <returns>出现的次数</returns>
        public  static int SubstringCount(string str, string substring)
        {
            if (str.Contains(substring))
            {
                string strReplaced = str.Replace(substring, "");
                return (str.Length - strReplaced.Length) / substring.Length;
            }

            return 0;
        }
            
            // 调用例子,这里仅提供参考的思路    
            private void FindPosition()
            { 
                    sTemp="aabbccdd\r\naa3323\r\naa325sdf\r\n233asdf554\r\n"; // 这里是原始字符串
                    int iCount = SubstringCount(sTemp, "\r\n"); // 这里\r\n是分割符
                    if (iCount > 3)
                    {
                        Regex reg = new Regex("\r\n");
                        Match mat = reg.Match(sTemp);
                        int iCountTemp = 0;
                        while (mat.Success)
                        {
                            iCountTemp++;
                            //MessageBox.Show(mat.Index.ToString());//位置
                            if (iCountTemp > 20)
                            {
                                sTemp = sTemp.Substring(0, mat.Index);
                                break;
                            }
                            mat = reg.Match(sTemp, mat.Index + mat.Length);
                        }
                    }
            }