Adding Days to a Date but Excluding Weekends

Question

Given a date how can I add a number of days to it, but exclude weekends. For example, given 11/12/2008 (Wednesday) and adding five will result in 11/19/2008 (Wednesday) rath

Answer 1

I created an extension that allows you to add or subtract business days. Use a negative number of businessDays to subtract. It seems to work in all cases.

namespace Extensions.DateTime
{
    public static class BusinessDays
    {
        public static System.DateTime AddBusinessDays(this System.DateTime source, int businessDays)
        {
            var dayOfWeek = businessDays < 0
                                ? ((int)source.DayOfWeek - 12) % 7
                                : ((int)source.DayOfWeek + 6) % 7;

            switch (dayOfWeek)
            {
                case 6:
                    businessDays--;
                    break;
                case -6:
                    businessDays++;
                    break;
            }

            return source.AddDays(businessDays + ((businessDays + dayOfWeek) / 5) * 2);
        }
    }
}

Example:

using System;
using System.Windows.Forms;
using Extensions.DateTime;

namespace AddBusinessDaysTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            label1.Text = DateTime.Now.AddBusinessDays(5).ToString();
            label2.Text = DateTime.Now.AddBusinessDays(-36).ToString();
        }
    }
}

Answer 2

This is better if anyone is looking for a TSQL solution. One line of code and works with negatives.

CREATE FUNCTION[dbo].[AddBusinessDays](@Date date,@n INT)RETURNS DATE AS BEGIN 
DECLARE @d INT;SET @d=4-SIGN(@n)*(4-DATEPART(DW,@Date));
RETURN DATEADD(D,@n+((ABS(@n)+@d-2)/5)*2*SIGN(@n)-@d/7,@Date)END

Answer 3

Given the number of the original day in the year D and original day in the week W and the number of workdays to add N, the next weekday number is

W + N % 5.

The next day in the year (with no wraparound check) is

D + ((N / 5) * 7) + N % 5).

This is assuming that you have integer division.

Answer 4

Formula will be: Workday(date,no.of days,(weekday(1)))

Try this. This will help.

Answer 5

F# flavor of http://stackoverflow.com/questions/1044688 's answer:

namespace FSharpBasics

module BusinessDays =

    open System;

    let private weekLength = 5

    (*operation*)
    let addBusinessDays (numberOfBusinessDays: int) (startDate: DateTime) =
        let startWeekDay = startDate.DayOfWeek
        let sign = Math.Sign(numberOfBusinessDays) 
        let weekendSlide, businessDaysSlide = 
            match startWeekDay with
            | DayOfWeek.Saturday when sign > 0 -> (2, -1)
            | DayOfWeek.Saturday when sign < 0 -> (-1, 1)   
            | DayOfWeek.Sunday when sign > 0 -> (1, -1)
            | DayOfWeek.Sunday when sign < 0 -> (-2, 1)
            | _ -> (0, 0)
        let baseStartDate = startDate.AddDays (float weekendSlide)        
        let days = Math.Abs (numberOfBusinessDays + businessDaysSlide) % weekLength
        let weeks = Math.Abs (numberOfBusinessDays + businessDaysSlide) / weekLength
        let baseWeekDay = int baseStartDate.DayOfWeek
        let oneMoreWeekend =
            if sign = 1 && days + baseWeekDay > 5 || sign = -1 && days >= baseWeekDay then 2
            else 0
        let totalDays = (weeks * 7) + days + oneMoreWeekend
        baseStartDate.AddDays (float totalDays)

    [<EntryPoint>]
    let main argv =
        let now = DateTime.Now 
        printfn "Now is %A" now
        printfn "13 business days from now would be %A" (addBusinessDays 13 now)
        System.Console.ReadLine() |> ignore
        0