Comments for YuEnDee

DateCorrector.cs

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

namespace EasyChallenge188_Dates
{
    class Program
    {
        static void Main(string[] args)
        {
            // I never bother with type names unless I have to.
            // Also, we can skip all the streamreader crap with this: 
            var RawDates = File.ReadLines(@"../../Input/Dates.txt").ToList();
            var CorrectedDates = new List<string>();

            // I really hate regular expressions, but you gotta
            // go with what works, right?
            // Initialize each Regex.
            Regex FirstForm = new Regex(@"\d{4}-\d{2}-\d{2}");
            Regex SecondForm = new Regex(@"\d{2}/\d{2}/\d{2}");
            Regex ThirdForm = new Regex(@"\d{2}#\d{2}#\d{2}");
            Regex FourthForm = new Regex(@"\d{2}\*\d{2}\*\d{4}");
            Regex FifthForm = new Regex(@"[a-zA-Z]{3} \d{2}, \d{2}");
            Regex SixthForm = new Regex(@"[a-zA-Z]{3} \d{2}, \d{4}");

            // Process each raw date.
            foreach (string date in RawDates)
            {
                // IsMatch() will return true if it succeeds
                // We can do this because you don't use the 
                // match result anywhere else.
                if (FirstForm.IsMatch(date))
                    CorrectedDates.Add(date);

                // else if prevents more than one form matching
                // any given date--just in case
                else if (SecondForm.IsMatch(date))
                {
                    string year = date.Substring(6, 2);
                    if (Convert.ToInt32(year) < 50)
                    {
                        year = "20" + year;
                    }
                    else
                    {
                        year = "19" + year;
                    }

                    string month = date.Substring(0, 2);

                    string day = date.Substring(3, 2);

                    // I'm not using a variable to store the corrected
                    // date before adding it to the list:
                    CorrectedDates.Add(String.Format("{0}-{1}-{2}", year, month, day));
                }

                else if (ThirdForm.IsMatch(date))
                {
                    string year = date.Substring(3, 2);
                    if (Convert.ToInt32(year) < 50)
                    {
                        year = "20" + year;
                    }
                    else
                    {
                        year = "19" + year;
                    }

                    string month = date.Substring(0, 2);

                    string day = date.Substring(6, 2);

                    CorrectedDates.Add(String.Format("{0}-{1}-{2}", year, month, day));
                }

                else if (FourthForm.IsMatch(date))
                {
                    string year = date.Substring(6, 4);

                    string month = date.Substring(3, 2);

                    string day = date.Substring(0, 2);

                    CorrectedDates.Add(String.Format("{0}-{1}-{2}", year, month, day));
                }

                else if (FifthForm.IsMatch(date))
                {
                    // Large blocks of repeated code are a great way 
                    // to introduce new and interesting bugs when 
                    // making changes.
                    string month = GetMonthFromAbbreviation(date);

                    string day = date.Substring(4, 2);

                    string year = date.Substring(8, 2);
                    if (Convert.ToInt32(year) < 50)
                    {
                        year = "20" + year;
                    }
                    else
                    {
                        year = "19" + year;
                    }

                    CorrectedDates.Add(String.Format("{0}-{1}-{2}", year, month, day));
                }

                else if (SixthForm.IsMatch(date))
                {
                    // Reuse the method from FifthForm
                    string month = GetMonthFromAbbreviation(date);

                    string day = date.Substring(4, 2);

                    string year = date.Substring(8, 4);

                    CorrectedDates.Add(String.Format("{0}-{1}-{2}", year, month, day));
                }
            }

            // This part is totally unnecessary:
            // Clear output file.
            //if (File.Exists(@"../../Output/CorrectedDates.txt"))
            //{
            //    File.WriteAllText(@"../../Output/CorrectedDates.txt", String.Empty);
            //}

            // Again, skip streamwriter/reader nonsense whenever possible
            File.WriteAllLines(@"../../Output/CorrectedDates.txt", CorrectedDates);

            // If you have to use sw/sr, using blocks are the shit:
            // Output all of the corrected dates into a file.
            //using (var writer = new StreamWriter(@"../../Output/CorrectedDates.txt"))
            //{
            //    foreach (string correctDate in CorrectedDates)
            //    {
            //        writer.WriteLine(correctDate);
            //    }
            //}

            /* Important:
             * ==========
             * 
             * If you decide not to use this using pattern, you have to close the streamwriter
             * or reader manually because, otherwise, there's really no telling what's gonna 
             * happen on exit. It's entirely possible that *nothing* will have been written to 
             * disk, or that the last part of your output will have been lost to the * nether, 
             * and all just because the buffer didn't get flushed.
             * */

            // No need to return from a void method
            //return;
        }

        private static string GetMonthFromAbbreviation(string date)
        {
            string month = date.Substring(0, 3);

            switch (month)
            {
                case "Jan":
                    month = "01";
                    break;

                case "Feb":
                    month = "02";
                    break;

                case "Mar":
                    month = "03";
                    break;

                case "Apr":
                    month = "04";
                    break;

                case "May":
                    month = "05";
                    break;

                case "Jun":
                    month = "06";
                    break;

                case "Jul":
                    month = "07";
                    break;

                case "Aug":
                    month = "08";
                    break;

                case "Sep":
                    month = "09";
                    break;

                case "Oct":
                    month = "10";
                    break;

                case "Nov":
                    month = "11";
                    break;

                case "Dec":
                    month = "12";
                    break;
            }
            return month;
        }
    }
}