Program.cs.bak

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

namespace SplitTextByDelimiter
{
    class Program
    {
        static void Main(string[] args)
        {
            string fileName;
            if (args.Length == 0)
            {
                Console.Write("Enter file name: ");
                fileName = Console.ReadLine();
            }
            else
            {
                fileName = args[0];
            }
            string[] file = File.ReadAllLines(fileName);
            //var list = new List<(string user, string pass)>(); //Tuple
            var listUser = new List<string>();
            var listPass = new List<string>();
            var delimiter = ";";

            foreach (string line in file)
            {
                if (args.Length > 1)
                {
                    delimiter = args[1];
                }
                var splited = line.Split(delimiter, 2);
                if (splited.Length > 0 && !string.IsNullOrWhiteSpace(splited[0]))
                    listUser.Add(splited[0]);

                if (splited.Length > 1 && !string.IsNullOrWhiteSpace(splited[1]))
                    listPass.Add(splited[1]);
                
            }

            File.WriteAllText("user.txt", String.Join(Environment.NewLine, listUser.Distinct()));
            File.WriteAllText("pass.txt", String.Join(Environment.NewLine, listPass.Distinct()));
        }
    }
}