Datetime - Get next tuesday

C# Problem Overview

How can I get the date of next Tuesday?

In PHP, it's as simple as strtotime('next tuesday');.

How can I achieve something similar in .NET

C# Solutions

Solution 1 - C#

As I've mentioned in the comments, there are various things you could mean by "next Tuesday", but this code gives you "the next Tuesday to occur, or today if it's already Tuesday":

DateTime today = DateTime.Today;
// The (... + 7) % 7 ensures we end up with a value in the range [0, 6]
int daysUntilTuesday = ((int) DayOfWeek.Tuesday - (int) today.DayOfWeek + 7) % 7;
DateTime nextTuesday = today.AddDays(daysUntilTuesday);

If you want to give "a week's time" if it's already Tuesday, you can use:

// This finds the next Monday (or today if it's Monday) and then adds a day... so the
// result is in the range [1-7]
int daysUntilTuesday = (((int) DayOfWeek.Monday - (int) today.DayOfWeek + 7) % 7) + 1;

... or you could use the original formula, but from tomorrow:

DateTime tomorrow = DateTime.Today.AddDays(1);
// The (... + 7) % 7 ensures we end up with a value in the range [0, 6]
int daysUntilTuesday = ((int) DayOfWeek.Tuesday - (int) tomorrow.DayOfWeek + 7) % 7;
DateTime nextTuesday = tomorrow.AddDays(daysUntilTuesday);

EDIT: Just to make this nice and versatile:

public static DateTime GetNextWeekday(DateTime start, DayOfWeek day)
{
    // The (... + 7) % 7 ensures we end up with a value in the range [0, 6]
    int daysToAdd = ((int) day - (int) start.DayOfWeek + 7) % 7;
    return start.AddDays(daysToAdd);
}

So to get the value for "today or in the next 6 days":

DateTime nextTuesday = GetNextWeekday(DateTime.Today, DayOfWeek.Tuesday);

To get the value for "the next Tuesday excluding today":

DateTime nextTuesday = GetNextWeekday(DateTime.Today.AddDays(1), DayOfWeek.Tuesday);

Solution 2 - C#

This should do the trick:

static DateTime GetNextWeekday(DayOfWeek day)
{
    DateTime result = DateTime.Now.AddDays(1);
    while( result.DayOfWeek != day )
        result = result.AddDays(1);
    return result;
}

Solution 3 - C#

There are less verbose and more clever/elegant solutions to this problem, but the following C# function works really well for a number of situations.

/// <summary>
/// Find the closest weekday to the given date
/// </summary>
/// <param name="includeStartDate">if the supplied date is on the specified day of the week, return that date or continue to the next date</param>
/// <param name="searchForward">search forward or backward from the supplied date. if a null parameter is given, the closest weekday (ie in either direction) is returned</param>
public static DateTime ClosestWeekDay(this DateTime date, DayOfWeek weekday, bool includeStartDate = true, bool? searchForward=true)
{
	if (!searchForward.HasValue && !includeStartDate) 
	{
		throw new ArgumentException("if searching in both directions, start date must be a valid result");
	}
	var day = date.DayOfWeek;
	int add = ((int)weekday - (int)day);
	if (searchForward.HasValue)
	{
		if (add < 0 && searchForward.Value)
		{
			add += 7;
		}
		else if (add > 0 && !searchForward.Value)
		{
			add -= 7;
		}
		else if (add == 0 && !includeStartDate)
		{
			add = searchForward.Value ? 7 : -7;
		}
	}
	else if (add < -3) 
	{
		add += 7; 
	}
	else if (add > 3)
	{
		add -= 7;
	}
	return date.AddDays(add);
}

Solution 4 - C#

@Jon Skeet good answer.

For previous Day:

private DateTime GetPrevWeekday(DateTime start, DayOfWeek day) {
    // The (... - 7) % 7 ensures we end up with a value in the range [0, 6]
    int daysToRemove = ((int) day - (int) start.DayOfWeek - 7) % 7;
    return start.AddDays(daysToRemove);
}

Thanks!!

Solution 5 - C#

DateTime nextTuesday = DateTime.Today.AddDays(((int)DateTime.Today.DayOfWeek - (int)DayOfWeek.Tuesday) + 7);

Solution 6 - C#

Very simple sample to include or exclude current date, you specify the date and the day the week you are interested in.

public static class DateTimeExtensions
{
    /// <summary>
    /// Gets the next date.
    /// </summary>
    /// <param name="date">The date to inspected.</param>
    /// <param name="dayOfWeek">The day of week you want to get.</param>
    /// <param name="exclDate">if set to <c>true</c> the current date will be excluded and include next occurrence.</param>
    /// <returns></returns>
    public static DateTime GetNextDate(this DateTime date, DayOfWeek dayOfWeek, bool exclDate = true)
    {
        //note: first we need to check if the date wants to move back by date - Today, + diff might move it forward or backwards to Today
        //eg: date - Today = 0 - 1 = -1, so have to move it forward
        var diff = dayOfWeek - date.DayOfWeek;
        var ddiff = date.Date.Subtract(DateTime.Today).Days + diff;

        //note: ddiff < 0 : date calculates to past, so move forward, even if the date is really old, it will just move 7 days from date passed in
        //note: ddiff >= (exclDate ? 6 : 7) && diff < 0 : date is into the future, so calculated future weekday, based on date
        if (ddiff < 0 || ddiff >= (exclDate ? 6 : 7) && diff < 0)
            diff += 7; 

        //note: now we can get safe values between 0 - 6, especially if past dates is being used
        diff = diff % 7;
        
        //note: if diff is 0 and we are excluding the date passed, we will add 7 days, eg: 1 week
        diff += diff == 0 & exclDate ? 7 : 0;

        return date.AddDays(diff);
    }
}

some test cases

[TestMethod]
    public void TestNextDate()
    {
        var date = new DateTime(2013, 7, 15);
        var start = date;
        //testing same month - forwardOnly
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Tuesday)); //16
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Wednesday)); //17
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Thursday)); //18
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Friday)); //19
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Saturday)); //20
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Sunday)); //21
        Assert.AreEqual(start.AddDays(1), date.GetNextDate(DayOfWeek.Monday)); //22

        //testing same month - include date
        Assert.AreEqual(start = date, date.GetNextDate(DayOfWeek.Monday, false)); //15
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Tuesday, false)); //16
        Assert.AreEqual(start.AddDays(1), date.GetNextDate(DayOfWeek.Wednesday, false)); //17

        //testing month change - forwardOnly
        date = new DateTime(2013, 7, 29);
        start = date;
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Tuesday)); //30
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Wednesday)); //31
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Thursday)); //2013/09/01-month increased
        Assert.AreEqual(start.AddDays(1), date.GetNextDate(DayOfWeek.Friday)); //02

        //testing year change
        date = new DateTime(2013, 12, 30);
        start = date;
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Tuesday)); //31
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Wednesday)); //2014/01/01 - year increased
        Assert.AreEqual(start = start.AddDays(1), date.GetNextDate(DayOfWeek.Thursday)); //02
    }

Solution 7 - C#

DateTime nexttuesday=DateTime.Today.AddDays(1);

while(nexttuesday.DayOfWeek!=DayOfWeek.Tuesday)
   nexttuesday = nexttuesday.AddDays(1);

Solution 8 - C#

Now in oneliner flavor - in case you need to pass it as parameter into some mechanism.

DateTime.Now.AddDays(((int)yourDate.DayOfWeek - (int)DateTime.Now.DayOfWeek + 7) % 7).Day

In this specific case:

DateTime.Now.AddDays(((int)DayOfWeek.Tuesday - (int)DateTime.Now.DayOfWeek + 7) % 7).Day

Solution 9 - C#

It could be an extension also, it all depends

public static class DateTimeExtensions
{
    public static IEnumerable<DateTime> Next(this DateTime date, DayOfWeek day)
    {
        // This loop feels expensive and useless, but the point is IEnumerable
        while(true)
        {
            if (date.DayOfWeek == day)
            {
                yield return date;
            }
            date = date.AddDays(1);
        }
    }
}

Usage

    var today = DateTime.Today;
    foreach(var monday in today.Next(DayOfWeek.Monday))
    {
        Console.WriteLine(monday);
        Console.ReadKey();
    }

Solution 10 - C#

Objective C Version:

+(NSInteger) daysUntilNextWeekday: (NSDate*)startDate withTargetWeekday: (NSInteger) targetWeekday
{
    NSInteger startWeekday = [[NSCalendar currentCalendar] component:NSCalendarUnitWeekday fromDate:startDate];
    return (targetWeekday - startWeekday + 7) % 7;
}

Content Type	Original Author	Original Content on Stackoverflow
Question	brenjt	View Question on Stackoverflow
Solution 1 - C#	Jon Skeet	View Answer on Stackoverflow
Solution 2 - C#	Sven	View Answer on Stackoverflow
Solution 3 - C#	Brent	View Answer on Stackoverflow
Solution 4 - C#	user4266998	View Answer on Stackoverflow
Solution 5 - C#	Mutt	View Answer on Stackoverflow
Solution 6 - C#	AJB	View Answer on Stackoverflow
Solution 7 - C#	Blindy	View Answer on Stackoverflow
Solution 8 - C#	Matas Vaitkevicius	View Answer on Stackoverflow
Solution 9 - C#	Alex Nolasco	View Answer on Stackoverflow
Solution 10 - C#	Max Hiroyuki Ueda	View Answer on Stackoverflow