Calculate the number of business days between two dates?

Question

In C#, how can I calculate the number of business (or weekdays) days between two dates?

Answer 1

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DateTime start = new DateTime(2014, 1, 1);
            DateTime stop = new DateTime(2014, 12, 31);

            int totalWorkingDays = GetNumberOfWorkingDays(start, stop);

            Console.WriteLine("There are {0} working days.", totalWorkingDays);
        }

        private static int GetNumberOfWorkingDays(DateTime start, DateTime stop)
        {
            TimeSpan interval = stop - start;

            int totalWeek = interval.Days / 7;
            int totalWorkingDays = 5 * totalWeek;

            int remainingDays = interval.Days % 7;


            for (int i = 0; i <= remainingDays; i++)
            {
                DayOfWeek test = (DayOfWeek)(((int)start.DayOfWeek + i) % 7);
                if (test >= DayOfWeek.Monday && test <= DayOfWeek.Friday)
                    totalWorkingDays++;
            }

            return totalWorkingDays;
        }
    }
}

Answer 2

I'll just share my solution. It worked for me, maybe I just don't notice/know that theres a bug. I started by getting the first incomplete week if there's any. a complete week was from sunday for saturday, so if the (int)_now.DayOfWeek was not 0(Sunday), the first week was incomplete.

I just subtract 1 to first weeks count for the first week's saturday then add it to new count;

Then I get the last incomplete week, then subtract 1 for it's sunday then add to new count.

Then finally, the number of complete weeks multiply by 5(weekdays) was added to new count.

public int RemoveNonWorkingDays(int numberOfDays){

            int workingDays = 0;

            int firstWeek = 7 - (int)_now.DayOfWeek;

            if(firstWeek < 7){

                if(firstWeek > numberOfDays)
                    return numberOfDays;

                workingDays += firstWeek-1;
                numberOfDays -= firstWeek;
            }


            int lastWeek = numberOfDays % 7;

            if(lastWeek > 0){

                numberOfDays -= lastWeek;
                workingDays += lastWeek - 1;

            }

            workingDays += (numberOfDays/7)*5;

            return workingDays;
        }

Answer 3

I know this question is already solved, but I thought I could provide a more straightforward-looking answer that may help other visitors in the future.

Here's my take at it:

public int GetWorkingDays(DateTime from, DateTime to)
{
    var dayDifference = (int)to.Subtract(from).TotalDays;
    return Enumerable
        .Range(1, dayDifference)
        .Select(x => from.AddDays(x))
        .Count(x => x.DayOfWeek != DayOfWeek.Saturday && x.DayOfWeek != DayOfWeek.Sunday);
}

This was my original submission:

public int GetWorkingDays(DateTime from, DateTime to)
{
    var totalDays = 0;
    for (var date = from; date < to; date = date.AddDays(1))
    {
        if (date.DayOfWeek != DayOfWeek.Saturday
            && date.DayOfWeek != DayOfWeek.Sunday)
            totalDays++;
    }

    return totalDays;
}

Answer 4

I was having trouble finding a solid TSQL version of this code. Below is essentially a conversion of the C# code here with addition of the Holiday table which should be used to pre-calculate holidays.

CREATE TABLE dbo.Holiday
(
    HolidayDt       DATE NOT NULL,
    Name            NVARCHAR(50) NOT NULL,
    IsWeekday       BIT NOT NULL,
    CONSTRAINT PK_Holiday PRIMARY KEY (HolidayDt)
)
GO
CREATE INDEX IDX_Holiday ON Holiday (HolidayDt, IsWeekday)

GO

CREATE function dbo.GetBusinessDays
(
     @FirstDay  datetime,
     @LastDay   datetime
) 
RETURNS INT
 AS
BEGIN
    DECLARE @BusinessDays INT, @FullWeekCount INT 
    SELECT  @FirstDay = CONVERT(DATETIME,CONVERT(DATE,@FirstDay))
        ,   @LastDay = CONVERT(DATETIME,CONVERT(DATE,@LastDay))

    IF @FirstDay > @LastDay
        RETURN NULL;

    SELECT @BusinessDays = DATEDIFF(DAY, @FirstDay, @LastDay) + 1 
    SELECT @FullWeekCount = @BusinessDays / 7;

    -- find out if there are weekends during the time exceedng the full weeks
    IF @BusinessDays > (@FullWeekCount * 7)
    BEGIN
    -- we are here to find out if there is a 1-day or 2-days weekend
    -- in the time interval remaining after subtracting the complete weeks
        DECLARE @firstDayOfWeek INT, @lastDayOfWeek INT;
        SELECT @firstDayOfWeek = DATEPART(DW, @FirstDay), @lastDayOfWeek = DATEPART(DW, @LastDay);

        IF @lastDayOfWeek < @firstDayOfWeek
                SELECT @lastDayOfWeek = @lastDayOfWeek + 7;

        IF @firstDayOfWeek <= 6 
            BEGIN
                IF (@lastDayOfWeek >= 7) --Both Saturday and Sunday are in the remaining time interval
                    BEGIN 
                        SELECT @BusinessDays = @BusinessDays - 2
                    END
                ELSE IF @lastDayOfWeek>=6 --Only Saturday is in the remaining time interval
                    BEGIN
                        SELECT @BusinessDays = @BusinessDays - 1
                    END

            END
        ELSE IF @firstDayOfWeek <= 7 AND @lastDayOfWeek >=7 -- Only Sunday is in the remaining time interval
        BEGIN 
            SELECT @BusinessDays = @BusinessDays - 1
        END
    END

    -- subtract the weekends during the full weeks in the interval
    DECLARE @Holidays INT;
    SELECT  @Holidays = COUNT(*) 
    FROM    Holiday 
    WHERE   HolidayDt BETWEEN @FirstDay AND @LastDay 
    AND     IsWeekday = CAST(1 AS BIT)

    SELECT @BusinessDays = @BusinessDays - (@FullWeekCount + @FullWeekCount) -- - @Holidays

    RETURN @BusinessDays
END

Answer 5

Here is one very simple solution for this problem. We have starting date, end date and "for loop" for encreasing the day and calculating to see if it's a workday or a weekend by converting to string DayOfWeek.

class Program
{
    static void Main(string[] args)
    {
        DateTime day = new DateTime();
        Console.Write("Inser your end date (example: 01/30/2015): ");
        DateTime endDate = DateTime.Parse(Console.ReadLine());
        int numberOfDays = 0;
        for (day = DateTime.Now.Date; day.Date < endDate.Date; day = day.Date.AddDays(1))
        {
            string dayToString = Convert.ToString(day.DayOfWeek);
            if (dayToString != "Saturday" && dayToString != "Sunday") numberOfDays++;
        }
        Console.WriteLine("Number of working days (not including local holidays) between two dates is "+numberOfDays);
    }
}

Answer 6

Here is an helper function I wrote for that task.
it also returns the count of weekends via the out parameter.
if you wish you can customize the "weekend" days in run time for countries that use different weekend days or to include holidays trough the weekendDays[] optional parameter :

public static int GetNetworkDays(DateTime startDate, DateTime endDate,out int totalWeekenDays, DayOfWeek[] weekendDays = null)
{
    if (startDate >= endDate)
    {
        throw new Exception("start date can not be greater then or equel to end date");
    }

    DayOfWeek[] weekends = new DayOfWeek[] { DayOfWeek.Sunday, DayOfWeek.Saturday };
    if (weekendDays != null)
    {
        weekends = weekendDays;
    }

    var totaldays = (endDate - startDate).TotalDays + 1; // add one to include the first day to
    var counter = 0;
    var workdaysCounter = 0;
    var weekendsCounter = 0;

    for (int i = 0; i < totaldays; i++)
    {

        if (weekends.Contains(startDate.AddDays(counter).DayOfWeek))
        {
            weekendsCounter++;
        }
        else
        {
            workdaysCounter++;
        }

        counter++;
    }

    totalWeekenDays = weekendsCounter;
    return workdaysCounter;
}