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How to count working 15 days and get enddate?

How to calculate actual working days of my when user checkin in hotel? I want to count working days only except Saturday and Sunday. Please check below function its count working days but in parameter I entered startdate and enddate.
I want send only startdate its automatically count 15 working days and return me enddate.
//Days count
public static double GetBusinessDays(DateTime startD, DateTime endD)
{
double calcBusinessDays =
1 + ((endD - startD).TotalDays * 5 -
(startD.DayOfWeek - endD.DayOfWeek) * 2) / 7;
if (endD.DayOfWeek == DayOfWeek.Saturday) calcBusinessDays--;
if (startD.DayOfWeek == DayOfWeek.Sunday) calcBusinessDays--;
return calcBusinessDays;
}
I want like this:
public static Datetime GetBusinessDays(DateTime startDate)
{
Datetime After15WorkingDaysDate;
return After15WorkingDaysDate;
}

Here are two methods.
The idea is to generate each date in the range, decide whether it is a Business Day, and only then add it to the result list.
GetBusinessDaysInRange returns a list of the dates of the Business Days between the given start and end date. End date is exclusive, i.e. if the end date is a Business Day, it will not be part of the result.
// Returns a list of the dates of the Business Days between the given start and end date
public static IEnumerable<DateTime> GetBusinessDaysInRange(DateTime startDate, DateTime endDate, DayOfWeek[] closedOn) {
if (endDate < startDate) {
throw new ArgumentException("endDate must be before startDate");
}
var businessDays = new List<DateTime>();
var date = startDate;
while (date < endDate) {
if (!closedOn.Contains(date.DayOfWeek)) {
businessDays.Add(date);
}
date = date.AddDays(1);
}
return businessDays;
}
GetFixedNumberOfBusinessDays returns a list of the dates of the Business Days from the given start with the given number of days (the method you asked for).
// Returns a list of the dates of the Business Days from the given start with the given number of days
public static IEnumerable<DateTime> GetFixedNumberOfBusinessDays(DateTime startDate, int numberOfBusinessDays, DayOfWeek[] closedOn) {
if (numberOfBusinessDays < 0) {
throw new ArgumentException("numberOfBusinessDays must be zero or positive.");
}
var businessDays = new List<DateTime>();
var date = startDate;
while (businessDays.Count() < numberOfBusinessDays) {
if (!closedOn.Contains(date.DayOfWeek)) {
businessDays.Add(date);
}
date = date.AddDays(1);
}
return businessDays;
}
The parameter DayOfWeek[] closedOn was introduced because you do not want to hardcode the days of the week that are not Business Days.
The return type was changed to IEnumerable<DateTime> so this method is more universal. If you only want the number of days and are not interested in the actual dates, just run a .Count() on the result. If you want the end date, call .Last().
.Net Fiddle with usage examples:
var closedOn = new DayOfWeek[] { DayOfWeek.Saturday, DayOfWeek.Sunday };
var start = new DateTime(2018, 07, 23);
var numberOfDays = 10;
var businessDays = GetFixedNumberOfBusinessDays(end, numberOfDays, closedOn);
int actualNumberOfBusinessDays = businessDays.Count(); // 10
DateTime endDate = businessDays.Last(); // Friday, August 3, 2018

It should be generic method. You can add different work day in another place.
public static DateTime AddWorkdays(this DateTime originalDate, int workDays)
{
DateTime tmpDate = originalDate;
while (workDays > 0)
{
tmpDate = tmpDate.AddDays(1);
if (tmpDate.DayOfWeek == DayOfWeek.Saturday ||
tmpDate.DayOfWeek == DayOfWeek.Sunday )
workDays--;
}
return tmpDate;
}
DateTime endDate = startDate.AddWorkdays(15);

Get Last Date of Given Month and Year in c#

i want c# code for getting Last Date of week for given month and year.
suppose given month is 1 and year is 2016 then method should return me
--01/02/2016
--01/09/2016
--01/16/2016
--01/23/2016
--01/30/2016
--02/06/2016

So you want a method which takes a year and a month as parameter and returns dates. Those dates should be the last dates of all weeks in that month, optionally also of following months.
This should work then:
public static IEnumerable<DateTime> GetLastWeekDatesOfMonth(int year, int month, DayOfWeek firstDayOfWeek = DayOfWeek.Monday, bool includeLaterMonths = false)
{
DateTime first = new DateTime(year, month, 1);
int daysOffset = (int)firstDayOfWeek - (int)first.DayOfWeek;
if (daysOffset < 0)
daysOffset = 7 - Math.Abs(daysOffset);
DateTime firstWeekDay = first.AddDays(daysOffset);
DateTime current = firstWeekDay.AddDays(-1); // last before week start
if (current.Month != month)
current = current.AddDays(7);
yield return current;
if (includeLaterMonths)
{
while (true)
{
current = current.AddDays(7);
yield return current;
}
}
else
{
while((current = current.AddDays(7)).Month == month)
yield return current;
}
}
Your sample:
var lastDates = GetLastWeekDatesOfMonth(2016, 1, DayOfWeek.Sunday, true);
foreach (DateTime dt in lastDates.Take(6))
Console.WriteLine(dt.ToShortDateString());

public static DateTime GetLastDateofWeek(int yr, int mnth, int week)
{
DateTime dt = new DateTime(yr, mnth, 1);
DateTime newdate = new DateTime();
if (dt.DayOfWeek == DayOfWeek.Monday)
{
newdate = dt.AddDays(((week - 1) * 7) + 5);
}
else
{
newdate = dt.AddDays((8 - (int)dt.DayOfWeek) % 7 + ((week - 2) * 7) + 5);
}
return newdate;
}

First get month and year, example:
int year = 2016;
int month = 1;
And then create a new instance of the DateTime class that represents the first saturday.
DateTime firstsaturday = new DateTime(year,month,1);
while(firstsaturday.DayOfWeek != DayOfWeek.Saturday)
{
firstsaturday = firstsaturday.AddDays(1);
]
Then create a List of DateTime values.
List<DateTime> saturdays = new List<DateTime>();
saturdays.Add(firstsaturday);
And then cycle through all saturdays using a loop.
DateTime CurrentSaturday = firstsaturday;
while(CurrentSaturday.AddDays(7).Month == month)
{
CurrentSaturday = CurrentSaturday.AddDays(7);
Saturdays.Add(CurrentSaturday);
}

You may try this code.
using System;
public class Program
{
public static void Main()
{
DateTime thisMonthInLastYear = DateTime.Now.AddYears(-1);
DateTime endOfMonth = new DateTime(thisMonthInLastYear.Year,
thisMonthInLastYear.Month,
DateTime.DaysInMonth(thisMonthInLastYear.Year,
thisMonthInLastYear.Month));
Console.WriteLine("Today : "+DateTime.Now.ToString("dd-MM-yyyy"));
Console.WriteLine("This Month in last years : "+endOfMonth.ToString("dd-MM-yyyy"));
Console.WriteLine("Next month in last years : "+endOfMonth.AddMonths(1).ToString("dd-MM-yyyy"));
}
}

C# check if current date is 1, 2 or 3 of the month, ignore weekend and additional List<DateTime>

I need to check if DateTime.Now is in the first 3 business days of each month (from Mon - Fri). I also need to provide a List<DateTime> with national holidays and these should be handled accordingly.
If DateTime.Now is Saturday and is 1 of the month, first 3 business days are Monday, Tuesday, Wednesday (3, 4, 5 of the month).
public bool IsBusinessDay()
{
DateTime now = DateTime.Now;
DateTime fbd = new DateTime();
DateTime sbd = new DateTime();
DateTime tbd = new DateTime();
DateTime fm = new DateTime(now.Year, now.Month, 1);
DateTime sm = new DateTime(now.Year, now.Month, 2);
DateTime tm = new DateTime(now.Year, now.Month, 3);
// first business day
if (fm.DayOfWeek == DayOfWeek.Sunday)
{
fbd = fm.AddDays(1);
}
else if (fm.DayOfWeek == DayOfWeek.Saturday)
{
fbd = fm.AddDays(2);
}
else
{
fbd = fm;
}
//second business day
if (sm.DayOfWeek == DayOfWeek.Sunday)
{
sbd = sm.AddDays(1);
}
else if (sm.DayOfWeek == DayOfWeek.Saturday)
{
sbd = sm.AddDays(2);
}
else
{
sbd = sm;
}
//third business day
if (tm.DayOfWeek == DayOfWeek.Sunday)
{
tbd = tm.AddDays(1);
}
else if (tm.DayOfWeek == DayOfWeek.Saturday)
{
tbd = tm.AddDays(2);
}
else
{
tbd = tm;
}
if (now == fdb || now == sbd || now == tbd)
{
return true;
}
return false;
}
Is this a good approach? How can I add a List<DateTime> with holidays and check that the current date is not holiday?
I have a feeling I'm over thinking this, and thinking it in a bad way. I don't know why but same feeling tells me there is an easier way to do it.

This should do what you want. You'll have to supply the set of holidays.
public static bool IsFirstThreeBusinessDays(DateTime date, HashSet<DateTime> holidays)
{
DateTime dt = new DateTime(date.Year, date.Month, 1);
int businessDaysSeen = 0;
while (businessDaysSeen < 3)
{
if (dt.DayOfWeek != DayOfWeek.Saturday &&
dt.DayOfWeek != DayOfWeek.Sunday &&
!holidays.Contains(dt))
{
if (dt == date.Date)
{
return true;
}
businessDaysSeen++;
}
dt = dt.AddDays(1);
}
return false;
}

You can also do this using LINQ.
public static bool IsFirstThreeBusinessDays(DateTime date, HashSet<DateTime> holidays)
{
var query =
Enumerable.Range(1, DateTime.DaysInMonth(date.Year, date.Month))
.Select(o => new DateTime(date.Year, date.Month, o))
.Where(o => o.DayOfWeek != DayOfWeek.Saturday && o.DayOfWeek != DayOfWeek.Sunday
&& !holidays.Contains(o))
.Take(3);
return query.Contains(date);
}

EDIT: I didn't read the question carefully enough, although parts of my old answer are still applicable. The approach I would take here is to create a method that enumerates the business days of the month, then take 3 from that.
Here's how:
public static IEnumerable<DateTime> BusinessDaysOfMonth(DateTime time)
{
var month = new DateTime(time.Year, time.Month, 1);
var nextMonth = month.AddMonths(1);
var current = month;
while(current < nextMonth)
{
if (IsWeekday(current) && !IsHoliday(current))
{
yield return current;
}
current = current.AddDays(1);
}
}
(note that some methods are taken from below). Then, all you need where you want to use this is:
// Get first three business days
var firstThreeBizDays = BusinessDaysOfMonth(DateTime.Now).Take(3);
// Check if today is one of them
var result = firstThreeBizDays.Contains(DateTime.Today);
OLD ANSWER:
Ok, so it looks like there's three conditions you need to ensure. They are:
It is the 1st, 2nd, or 3rd day of the month
It is not Saturday or Sunday
The current date is not contained in some set of dates representing holidays
This translates fairly straightforwardly to code:
public static bool IsFirstThreeDays(DateTime time) => time.Day < 4;
public static bool IsWeekday(DateTime time)
{
var dow = time.DayOfWeek;
return dow != DayOfWeek.Saturday && dow != DayOfWeek.Sunday;
}
public bool IsHoliday(DateTime time)
{
ISet<DateTime> holidays = ??; // Decide whether this is a member or an arg
return holidays.Contains(time.Date);
}
Note that the holidays set needs to contain the Day component of any DateTime from each holiday.
Now your method is presumably just:
public static bool IsDayWhatYouWant()
{
var now = DateTime.UtcNow;
return IsFirstThreeDays(now) && IsWeekday(now) && !IsHoliday(now);
}

An Optimized algorithm for finding all Sundays and Fridays for a given interval

I have a flag enum for representing every day of the week. (Sunday, Monday etc.). Lets call this the WeekDay enum. Now given a interval find all dates for the days in the WeekDaysvariable.
For eg: WeekDays daysAll = WeekDays.Sunday | WeekDays.Friday;
Now find the dates for all the Sunday and Friday dates in a given interval.
So i thought of the following logic: Find the first Sunday, Friday, as in the above example.
Add these dates to a temporary dictionary. Now iterate that dictionary and keep on adding 7 days till the end interval is reached.
int dayCounter = 0;
WeekDays daysAll = WeekDays.Sunday | WeekDays.Friday;
Dictionary<DayOfWeek, DateTime> tempDict = new Dictionary<DayOfWeek, DateTime>();
for (var day = intervalStartDate.Date; (dayCounter < 7 && day.Date <= intervalEndDate.Date); day = day.AddDays(1))
{
WeekDays check = GetWeekDayFromDayOfWeek(day.DayOfWeek); //This Function converts from the DateTime DayOfweek enum to the WeekDays enum.
if ((check & daysAll) == check)
{
tempDict.Add(day.DayOfWeek, day);
}
dayCounter++;
}
Now keep adding 7 days for every date in the dict till end interval is reached:
if (tempDict.Keys.Count > 0)
{
List<DateTime> allDates = new List<DateTime>();
var keys = new List<DayOfWeek>(tempDict.Keys);
bool opComplete = false;
while (!opComplete)
{
foreach (DayOfWeek dayOfWeek in keys)
{
if (tempDict[dayOfWeek] > intervalEndDate.Date) { opComplete = true; break; }
allDates.Add(tempDict[dayOfWeek]);
tempDict[dayOfWeek] = tempDict[dayOfWeek].AddDays(7);
}
}
}
So my question is: Can this algorithm be improved? Can LinQ be used to make the intent more clearer in the code itself?

Performance optimization and clearer code are not the same in most cases.
The clearer LINQ version would be like this:
public IEnumerable<DateTime> IntervalDays(DateTime start, DateTime end)
{
if (start > end)
yield break;
var d = start.Date;
while (d <= end.Date)
{
yield return d;
d = d.AddDays(1);
}
}
and the you write the query as in this example:
IntervalDays(startDate, endDate)
.Where(d=>d.DayOfWeek==DayOfWeek.Friday || d.DayOfWeek==DayOfWeek.Sunday);
The good thing here is you can easily query other days of the week etc.
For the optimized code, if you mean performance, you'd better not iterate one by one but find the first Friday or Sunday and move along by adding 2 or 5 days depending on the date

Few ways, as a general method, pass in the day of week you want with start and end dates.
private List<DateTime> GetDates(DateTime startDate, DateTime endDate, DayOfWeek dayOfWeek)
{
var returnDates = new List<DateTime>();
for (DateTime dateCounter = startDate; dateCounter < endDate; dateCounter = dateCounter.AddDays(1))
{
if (dateCounter.DayOfWeek == dayOfWeek)
{
returnDates.Add(dateCounter);
}
}
return returnDates;
}
Or return full date range and query that using linq.
private List<DateTime> GetDates(DateTime startDate, DateTime endDate)
{
var returnDates = new List<DateTime>();
for (DateTime dateCounter = startDate; dateCounter < endDate; dateCounter = dateCounter.AddDays(1))
{
returnDates.Add(dateCounter);
}
return returnDates;
}
query:
var myDates = GetDates(DateTime.Now, DateTime.Now.AddDays(30)).Where(i => i.DayOfWeek == DayOfWeek.Friday);

C# - What is the best way to get a list of the weeks in a month, given a starting weekday?

I need to get a list of weeks for a given month, with Monday as the start day.
So for example, for the month of February 2009, this method would return:
2/2/2009
2/9/2009
2/16/2009
2/23/2009

// Get the weeks in a month
DateTime date = DateTime.Today;
// first generate all dates in the month of 'date'
var dates = Enumerable.Range(1, DateTime.DaysInMonth(date.Year, date.Month)).Select(n => new DateTime(date.Year, date.Month, n));
// then filter the only the start of weeks
var weekends = from d in dates
where d.DayOfWeek == DayOfWeek.Monday
select d;

public static List<DateTime> GetWeeks(
this DateTime month, DayOfWeek startOfWeek)
{
var firstOfMonth = new DateTime(month.Year, month.Month, 1);
var daysToAdd = ((Int32)startOfWeek - (Int32)month.DayOfWeek) % 7;
var firstStartOfWeek = firstOfMonth.AddDays(daysToAdd);
var current = firstStartOfWeek;
var weeks = new List<DateTime>();
while (current.Month == month.Month)
{
weeks.Add(current);
current = current.AddDays(7);
}
return weeks;
}

Here's a solution (effectively one line) using C# 3.0/LINQ, in case you're interested:
var month = new DateTime(2009, 2, 1);
var weeks = Enumerable.Range(0, 4).Select(n => month.AddDays(n * 7 - (int)month.DayOfWeek + 1)).TakeWhile(monday => monday.Month == month.Month);

int year = 2009;
int month = 2;
DateTime startDate = new DateTime(year, month, 1);
DateTime endDate = startDate.AddMonths(1);
while (startDate.DayOfWeek != DayOfWeek.Monday)
startDate = startDate.AddDays(1);
for (DateTime result = startDate; result < endDate; result = result.AddDays(7))
DoWhatYouWant(result);

How about this?
public IEnumerable<DateTime> GetWeeks(DateTime date, DayOfWeek startDay)
{
var list = new List<DateTime>();
DateTime first = new DateTime(date.Year, date.Month, 1);
for (var i = first; i < first.AddMonths(1); i = i.AddDays(1))
{
if (i.DayOfWeek == startDay)
list.Add(i);
}
return list;
}

Something like the following pseudo-code should work:
Determine the start date of the month (use month and year from a date and set the day to 1
Determine the end date of the month (start date + 1 month)
Determine the first date that is a monday (this is your first item in the list)
Add 7 days to find the next date and repeat until you read or pass the month end

Just change the response line to what ever you need to do with it
protected void PrintDay(int year, int month, DayOfWeek dayName)
{
CultureInfo ci = new CultureInfo("en-US");
for (int i = 1 ; i <= ci.Calendar.GetDaysInMonth (year, month); i++)
{
if (new DateTime (year, month, i).DayOfWeek == dayName)
Response.Write (i.ToString() + "<br/>");
}
}
Quick solution: i don't think there is a built in function for it....

I see you got your answer, but I wanted to share with you a helper class I created for one of my projects. It's far to be a comprehansive class, but might help...
public static class WeekHelper {
#region Public Methods
public static DateTime GetWeekStart(DateTime date) {
DateTime weekStart;
int monday = 1;
int crtDay = (int)date.DayOfWeek;
if (date.DayOfWeek == DayOfWeek.Sunday)
crtDay = 7;
int difference = crtDay - monday;
weekStart = date.AddDays(-difference);
return weekStart;
}
public static DateTime GetWeekStop(DateTime date) {
DateTime weekStart;
int sunday = 7;
int crtDay = (int)date.DayOfWeek;
if (date.DayOfWeek == DayOfWeek.Sunday)
crtDay = 7;
int difference = sunday - crtDay;
weekStart = date.AddDays(difference);
return weekStart;
}
public static void GetWeekInterval(int year, int weekNo,
out DateTime weekStart, out DateTime weekStop) {
GetFirstWeekOfYear(year, out weekStart, out weekStop);
if (weekNo == 1)
return;
weekNo--;
int daysToAdd = weekNo * 7;
DateTime dt = weekStart.AddDays(daysToAdd);
GetWeekInterval(dt, out weekStart, out weekStop);
}
public static List<KeyValuePair<DateTime, DateTime>> GetWeekSeries(DateTime toDate) {
//gets week series from beginning of the year
DateTime dtStartYear = new DateTime(toDate.Year, 1, 1);
List<KeyValuePair<DateTime, DateTime>> list = GetWeekSeries(dtStartYear, toDate);
if (list.Count > 0) {
KeyValuePair<DateTime, DateTime> week = list[0];
list[0] = new KeyValuePair<DateTime, DateTime>(dtStartYear, week.Value);
}
return list;
}
public static List<KeyValuePair<DateTime, DateTime>> GetWeekSeries(DateTime fromDate, DateTime toDate) {
if (fromDate > toDate)
return null;
List<KeyValuePair<DateTime, DateTime>> list = new List<KeyValuePair<DateTime, DateTime>>(100);
DateTime weekStart, weekStop;
toDate = GetWeekStop(toDate);
while (fromDate <= toDate) {
GetWeekInterval(fromDate, out weekStart, out weekStop);
list.Add(new KeyValuePair<DateTime, DateTime>(weekStart, weekStop));
fromDate = fromDate.AddDays(7);
}
return list;
}
public static void GetFirstWeekOfYear(int year, out DateTime weekStart, out DateTime weekStop) {
DateTime date = new DateTime(year, 1, 1);
GetWeekInterval(date, out weekStart, out weekStop);
}
public static void GetWeekInterval(DateTime date,
out DateTime dtWeekStart, out DateTime dtWeekStop) {
dtWeekStart = GetWeekStart(date);
dtWeekStop = GetWeekStop(date);
}
#endregion Public Methods
}

This works beautifully! All you have to do is get the first day of the month you want to get the weeks for and then this will give you the first day of every week. You need to get 5 weeks (not 4) so the Enumerable.Range counts out 5 instead of 4.
var date = new DateTime(DateTime.Today.Year, DateTime.Today.Month, 1);
var weeks = from n in Enumerable.Range(0, 5)
select date.AddDays(7 * n + (-1 * (int)date.DayOfWeek));

Here's what i did, using Chaowlert's code as a starting base. Basically i modified that you need to check if adding the days in the for overflows to the next month, so i don't add 4 days (monday to friday), but actually the minimum between 4 and the number of remaining days in the month. Also, i check if the current day is a weekend, otherwise add days until it's a weekday. My purpose is to print the weeks in a month, from monday to friday
DateTime fechaInicio = new DateTime(año, mes, 1);
DateTime fechaFin = fechaInicio.AddMonths(1);
int diasHastaFinMes = 0;
while (esFinDeSemana(fechaInicio))
fechaInicio = fechaInicio.AddDays(1);
for (DateTime fecha = fechaInicio; fecha < fechaFin; fecha = fecha.AddDays(7))
{
diasHastaFinMes = DateTime.DaysInMonth(fecha.Year, fecha.Month) - fecha.Day;
printWeeks(fecha, fecha.AddDays(Math.Min(4, diasHastaFinMes)));
}