Basic Markup Language

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace _1_Exam_13May2016_3_BasicMarkLanguage
{
    class Program
    {
        static void Main()
        {
            string input = Console.ReadLine();

            int n = 1;
            while (input!="<stop/>")
            {
                string pattern = @"^\s*<\s*([a-z]+)\s+([a-z]+\s*=\s*""\s*([0-9]+)\s*""\s*)?[a-z]+\s*=\s*""([^""]*)""\s*\/\s*>\s*$";
                Match match = Regex.Match(input, pattern);
                string command = match.Groups[1].ToString();
                string value = match.Groups[3].ToString();
                string content = match.Groups[4].ToString();
                string result = "";
              if (content.Length > 0)
             {
                switch (command)
                {
                    case "inverse": result = Inverse(content); Console.WriteLine("{0}. {1}", n, result); n++; break;
                    case "reverse": result = Reverse(content); Console.WriteLine("{0}. {1}", n, result); n++; break;
                    case "repeat":
                        if (int.Parse(value) > 0)
                        {
                            for (int i = 1; i <= int.Parse(value); i++)
                            {
                                Console.WriteLine("{0}. {1}", n, content);
                                n++;
                            }
                        }
                        break;

                    default:  break;
                }
             }

            input = Console.ReadLine();
            }
        }

        private static string Reverse(string content)
        {
            StringBuilder sb = new StringBuilder();
            for (int i=content.Length-1; i >= 0; i--)
            {
                sb.Append(content[i]);
            }
            content = sb.ToString();
            return content;
        }

        private static string Inverse(string content)
        {
            StringBuilder sb = new StringBuilder();
            foreach (var item in content)
            {
                if ( char.IsLower(item)) { sb.Append(char.ToUpper(item)); }
                else if (char.IsUpper(item)) { sb.Append(char.ToLower(item)); }
                else { sb.Append(item); }
            }
            content = sb.ToString();
            return content;
        }



    }
}


// My older solution 100 from 100:

//string input = Console.ReadLine();
//string patternContent = @"content\s*=\s*""([^""]*)""";
//string patternCommand = @"inverse|reverse|repeat\s+value\s*=\s*""\s*([\d]+)\s*""";
//int counter = 0;
//            while ((!input.Contains("stop")) && input.Contains("content"))
//            {
//                Match matchCont = Regex.Match(input, patternContent);
//string content = matchCont.Groups[1].ToString();
//                if (content == "") { input = Console.ReadLine(); continue; }
//                Match matchCom = Regex.Match(input, patternCommand);

//string resultContent = "";
//                if (matchCom.ToString() == "inverse")
//                {
//                    for (int i = 0; i<content.Length; i++)
//                    {
//                        string letter = "";
//                        if (content[i] >= 65 && content[i] <= 90)
//                        { letter = content[i].ToString().ToLower(); resultContent += letter; }
//                        else { letter = content[i].ToString().ToUpper(); resultContent += letter; }
//                    }
//                    counter++;
//                    Console.WriteLine("{0}. {1}", counter, resultContent);
//                }
//                else if (matchCom.ToString() == "reverse")
//                {
//                    char[] reversed = content.Reverse().ToArray();
//resultContent = string.Join("", reversed);
//counter++;
//                    Console.WriteLine("{0}. {1}", counter, resultContent);
//                }
//                else
//                {
//                    string repeatTimesStr = matchCom.Groups[1].ToString();
//int repeatTimes = int.Parse(repeatTimesStr);
//                    for (int i = 0; i<repeatTimes; i++)
//                    {
//                        counter++;
//                        Console.WriteLine("{0}. {1}", counter, content);
//                    }
//                    if (repeatTimes == 0)
//                    {
//                        input = Console.ReadLine(); continue;
//                    }
//                }

//                input = Console.ReadLine();
//            }