Calculate the Week day of months from given date?

Question

I am struggling to find an easy and efficient solution to calculating the week day of a month. For example, if a given date is the first Monday Monday 5th March 2018 then I want to get the date for each first Monday of a month for the next 6 months e.g: Monday 2nd April 2018 and Monday 3rd May 2018 and so on.

I have tried to use the following code from this question. However, the code below only returns the week number I would like it to return the whole date.

static class DateTimeExtensions
{
    static GregorianCalendar _gc = new GregorianCalendar();
    public static int GetWeekOfMonth(this DateTime time)
    {
        DateTime first = new DateTime(time.Year, time.Month, 1);
        return time.GetWeekOfYear() - first.GetWeekOfYear() + 1;
    }

    static int GetWeekOfYear(this DateTime time)
    {
        return _gc.GetWeekOfYear(time, CalendarWeekRule.FirstDay, DayOfWeek.Monday);
    }
}

But I am confused and don't know how I can modify the above code to solve this issue. Any help will be appreciated.

Answer 1

Recently Microsoft has released a DateTimeRecognizer project on GitHub which allows you to parse natural language datetime into Plain Old C# DateTime Objects. It's throughly tested, so no monkey work there.

They have also released a nuget package of the same. Which you can install via the nuget package manager.

---

First install the nuget package:

---

While, all of that is out of the way. I have developed a small utility program, which first extracts the datetime from the natural language then finds the first occurrence of subsequent dates of the same day next month.

using Microsoft.Recognizers.Text;
using Microsoft.Recognizers.Text.DateTime;
using System;
using System.Collections.Generic;
using System.Linq;

namespace RecognizerDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                string Query = string.Empty;
                Console.WriteLine("Enter date: ");
                Query = Console.ReadLine();
                DateTime parsedDate = ExtractDateFromNaturalLanguage(Query);
                List<DateTime> futureDates = GetSubsequentDateTimes(parsedDate);


                foreach (var item in futureDates)
                {
                    Console.WriteLine(item.ToLongDateString());
                }

            }
            catch(Exception ex)
            {
                Console.WriteLine($"Failed because: {ex.Message}");
            }
        }

    static List<DateTime> GetSubsequentDateTimes(DateTime date)
    {
        try
        {
            List<DateTime> futureDates = new List<DateTime>();
            DayOfWeek dayOfWeekOriginalDate = date.DayOfWeek;
            int month = date.Month;

            futureDates.Add(date);

            for (int i = month + 1; i <= month + 5; i++)
            {
                DateTime dt = new DateTime(date.Year, i, 1);

                while (dt.DayOfWeek != dayOfWeekOriginalDate)
                {
                    dt = dt.AddDays(1);
                }
                futureDates.Add(dt);
            }

            return futureDates;
        }
        catch(Exception ex)
        {
            throw;
        }
    }

        static DateTime ExtractDateFromNaturalLanguage(string Query)
        {
            try
            {
                DateTimeModel model = DateTimeRecognizer.GetInstance().GetDateTimeModel(Culture.English);
                List<ModelResult> parsedResults = model.Parse(Query);

                Dictionary<string, string> resolvedValue = (parsedResults.SelectMany(x => x.Resolution).FirstOrDefault().Value as List<Dictionary<string, string>>).FirstOrDefault();

                string parsedDate = string.Empty;

                if (resolvedValue["type"] == "daterange")
                    parsedDate = resolvedValue["start"];

                if (resolvedValue["type"] == "date")
                    parsedDate = resolvedValue["value"];

                DateTime parsedDateTimeObject = DateTime.Parse(parsedDate);

                return parsedDateTimeObject;
            }
            catch (Exception ex)
            {
                throw;
            }
        }
    }
}

---

This, is what you need.