URL_to_(host-with-folder), C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

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

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
                //==================TEST====================

//string address = "https://domain.com";
				//string address = "irc://123.45.67.89:1234";
				//string address = "bitcoin://123.45.67.89:1234/folder.home"; 		//folder seems, like a file
				//string address = "ftp://domain.com/index.html"; 					//file not included to path
				//string address = "tox://domain.com:1234/folder"; 					//this can be the file without extension

//string address = "https://domain.com/";
				//string address = "skype://123.45.67.89:1234/";
				//string address = "tg://123.45.67.89:1234/folder.home/"; 			//with slash this is folder
				//string address = "viber://domain.com/index.html/"; 				//and this
				string address = "http://domain.com:1234/folder/";

//==================TEST====================
                Console.WriteLine("address: "+ address+"\n\n"+
                                  "splitted array:");

string[] items = address.Split('/');	//split by slash
                string host_and_folder = "";			//empty string
                string item = "";						//empty temp item
				int len = items.Length;					//array length
				int last = len-1;						//last element index.
                
                for(int i = 0; i<len; i++){				//check all items
					Console.WriteLine("item: {0}, value: '{1}'", i, items[i]);	//write item, value
                    item = items[i];											//write item to temp string
                    if(
							i!=last												//if this is not last item
						|| 	(i==2 && len==3)									//or if domain/IP(+port) only, without slash
					){
						item = item+'/';										//add slash
					}
                    if(
							(len!=3 && i==last)									//if last item
						&& 	item.IndexOf('.')!=-1								//and if dot found
					){
                        //do not add this file to path							//maybe, this is filename. If not - add slash in the end...
                    }else{
                        host_and_folder = String.Concat(host_and_folder, item);	//if not last item or if dot not found, add this as folder.
                    }
                }

Console.WriteLine("\nitems.Length '{0}',\n"+
                                  "last item: items[{1}] = {2}\n",
                                  len, last,
                                  items[last]
                );
                Console.WriteLine("result path: host_and_folder = '{0}'", host_and_folder);

}
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,17 sec, absolute running time: 0,13 sec, cpu time: 0,11 sec, average memory usage: 12 Mb, average nr of threads: 2, absolute service time: 0,32 sec