CODEWITHSUNDEEP
c#asp.netdatetimeloops
Paul Mignard
Paul Mignard

Reputation: 5934

How do I loop through a date range?

I'm not even sure how to do this without using some horrible for loop/counter type solution. Here's the problem:

I'm given two dates, a start date and an end date and on a specified interval I need to take some action. For example: for every date between 3/10/2009 on every third day until 3/26/2009 I need to create an entry in a List. So my inputs would be:

DateTime StartDate = "3/10/2009";
DateTime EndDate = "3/26/2009";
int DayInterval = 3;

and my output would be a list that has the following dates:

3/13/2009 3/16/2009 3/19/2009 3/22/2009 3/25/2009

So how the heck would I do something like this? I thought about using a for loop that would iterate between every day in the range with a separate counter like so:

int count = 0;

for(int i = 0; i < n; i++)
{
     count++;
     if(count >= DayInterval)
     {
          //take action
          count = 0;
     }

}

But it seems like there could be a better way?

Upvotes: 262

Views: 235842

Answers (17)

GDavoli
GDavoli

Reputation: 616

If you convert your dates to OADate you can loop thru them as you would do with any double number.

DateTime startDate = new DateTime(2022, 1, 1);
DateTime endDate = new DateTime(2022, 12, 31);

for (double loopDate = startDate.ToOADate(); loopDate <= endDate.ToOADate(); loopDate++)
{
    DateTime selectedDate;
    selectedDate = DateTime.FromOADate(loopDate);
}

Upvotes: 0

mko
mko

Reputation: 7325

Here are my 2 cents in 2020.

Enumerable.Range(0, (endDate - startDate).Days + 1)
.ToList()
.Select(a => startDate.AddDays(a));

Upvotes: 4

Sunil Joshi
Sunil Joshi

Reputation: 83

DateTime begindate = Convert.ToDateTime("01/Jan/2018");
DateTime enddate = Convert.ToDateTime("12 Feb 2018");
 while (begindate < enddate)
 {
    begindate= begindate.AddDays(1);
    Console.WriteLine(begindate + "  " + enddate);
 }

Upvotes: 7

DantaliaN
DantaliaN

Reputation: 163

@jacob-sobus and @mquander and @Yogurt not exactly correct.. If I need the next day I wait 00:00 time mostly

    public static IEnumerable<DateTime> EachDay(DateTime from, DateTime thru)
    {
        for (var day = from.Date; day.Date <= thru.Date; day = day.NextDay())
            yield return day;
    }

    public static IEnumerable<DateTime> EachMonth(DateTime from, DateTime thru)
    {
        for (var month = from.Date; month.Date <= thru.Date || month.Year == thru.Year && month.Month == thru.Month; month = month.NextMonth())
            yield return month;
    }

    public static IEnumerable<DateTime> EachYear(DateTime from, DateTime thru)
    {
        for (var year = from.Date; year.Date <= thru.Date || year.Year == thru.Year; year = year.NextYear())
            yield return year;
    }

    public static DateTime NextDay(this DateTime date)
    {
        return date.AddTicks(TimeSpan.TicksPerDay - date.TimeOfDay.Ticks);
    }

    public static DateTime NextMonth(this DateTime date)
    {
        return date.AddTicks(TimeSpan.TicksPerDay * DateTime.DaysInMonth(date.Year, date.Month) - (date.TimeOfDay.Ticks + TimeSpan.TicksPerDay * (date.Day - 1)));
    }

    public static DateTime NextYear(this DateTime date)
    {
        var yearTicks = (new DateTime(date.Year + 1, 1, 1) - new DateTime(date.Year, 1, 1)).Ticks;
        var ticks = (date - new DateTime(date.Year, 1, 1)).Ticks;
        return date.AddTicks(yearTicks - ticks);
    }

    public static IEnumerable<DateTime> EachDayTo(this DateTime dateFrom, DateTime dateTo)
    {
        return EachDay(dateFrom, dateTo);
    }

    public static IEnumerable<DateTime> EachMonthTo(this DateTime dateFrom, DateTime dateTo)
    {
        return EachMonth(dateFrom, dateTo);
    }

    public static IEnumerable<DateTime> EachYearTo(this DateTime dateFrom, DateTime dateTo)
    {
        return EachYear(dateFrom, dateTo);
    }

Upvotes: 1

McNiel Viray
McNiel Viray

Reputation: 101

Iterate every 15 minutes

DateTime startDate = DateTime.Parse("2018-06-24 06:00");
        DateTime endDate = DateTime.Parse("2018-06-24 11:45");

        while (startDate.AddMinutes(15) <= endDate)
        {

            Console.WriteLine(startDate.ToString("yyyy-MM-dd HH:mm"));
            startDate = startDate.AddMinutes(15);
        }

Upvotes: 0

porya ras
porya ras

Reputation: 490

you can use this.

 DateTime dt0 = new DateTime(2009, 3, 10);
 DateTime dt1 = new DateTime(2009, 3, 26);

 for (; dt0.Date <= dt1.Date; dt0=dt0.AddDays(3))
 {
    //Console.WriteLine(dt0.Date.ToString("yyyy-MM-dd"));
    //take action
 }

Upvotes: 1

amd
amd

Reputation: 21502

1 Year later, may it help someone,

This version includes a predicate, to be more flexible.

Usage

var today = DateTime.UtcNow;
var birthday = new DateTime(2018, 01, 01);

Daily to my birthday

var toBirthday = today.RangeTo(birthday);

Monthly to my birthday, Step 2 months

var toBirthday = today.RangeTo(birthday, x => x.AddMonths(2));

Yearly to my birthday

var toBirthday = today.RangeTo(birthday, x => x.AddYears(1));

Use RangeFrom instead

// same result
var fromToday = birthday.RangeFrom(today);
var toBirthday = today.RangeTo(birthday);

Implementation

public static class DateTimeExtensions 
{

    public static IEnumerable<DateTime> RangeTo(this DateTime from, DateTime to, Func<DateTime, DateTime> step = null)
    {
        if (step == null)
        {
            step = x => x.AddDays(1);
        }

        while (from < to)
        {
            yield return from;
            from = step(from);
        }
    }

    public static IEnumerable<DateTime> RangeFrom(this DateTime to, DateTime from, Func<DateTime, DateTime> step = null)
    {
        return from.RangeTo(to, step);
    }
}

Extras

You could throw an Exception if the fromDate > toDate, but I prefer to return an empty range instead []

Upvotes: 14

TLiebe
TLiebe

Reputation: 7996

You can use the DateTime.AddDays() function to add your DayInterval to the StartDate and check to make sure it is less than the EndDate.

Upvotes: 2

Robert Peter Bronstein
Robert Peter Bronstein

Reputation: 166

you have to be careful here not to miss the dates when in the loop a better solution would be.

this gives you the first date of startdate and use it in the loop before incrementing it and it will process all the dates including the last date of enddate hence <= enddate.

so the above answer is the correct one.

while (startdate <= enddate)
{
    // do something with the startdate
    startdate = startdate.adddays(interval);
}

Upvotes: 0

Rejwanul Reja
Rejwanul Reja

Reputation: 1491

According to the problem you can try this...

// looping between date range    
while (startDate <= endDate)
{
    //here will be your code block...

    startDate = startDate.AddDays(1);
}

thanks......

Upvotes: 5

Jacob Sobus
Jacob Sobus

Reputation: 981

Code from @mquander and @Yogurt The Wise used in extensions:

public static IEnumerable<DateTime> EachDay(DateTime from, DateTime thru)
{
    for (var day = from.Date; day.Date <= thru.Date; day = day.AddDays(1))
        yield return day;
}

public static IEnumerable<DateTime> EachMonth(DateTime from, DateTime thru)
{
    for (var month = from.Date; month.Date <= thru.Date || month.Month == thru.Month; month = month.AddMonths(1))
        yield return month;
}

public static IEnumerable<DateTime> EachDayTo(this DateTime dateFrom, DateTime dateTo)
{
    return EachDay(dateFrom, dateTo);
}

public static IEnumerable<DateTime> EachMonthTo(this DateTime dateFrom, DateTime dateTo)
{
    return EachMonth(dateFrom, dateTo);
}

Upvotes: 20

REDace0
REDace0

Reputation: 131

You might consider writing an iterator instead, which allows you to use normal 'for' loop syntax like '++'. I searched and found a similar question answered here on StackOverflow which gives pointers on making DateTime iterable.

Upvotes: 1

gilbertc
gilbertc

Reputation: 1069

DateTime startDate = new DateTime(2009, 3, 10);
DateTime stopDate = new DateTime(2009, 3, 26);
int interval = 3;

for (DateTime dateTime=startDate;
     dateTime < stopDate; 
     dateTime += TimeSpan.FromDays(interval))
{

}

Upvotes: 9

devnull
devnull

Reputation: 2860

DateTime startDate = new DateTime(2009, 3, 10);
DateTime stopDate = new DateTime(2009, 3, 26);
int interval = 3;

while ((startDate = startDate.AddDays(interval)) <= stopDate)
{
    // do your thing
}

Upvotes: 3

Jon Skeet
Jon Skeet

Reputation: 1503290

I have a Range class in MiscUtil which you could find useful. Combined with the various extension methods, you could do:

foreach (DateTime date in StartDate.To(EndDate).ExcludeEnd()
                                   .Step(DayInterval.Days())
{
    // Do something with the date
}

(You may or may not want to exclude the end - I just thought I'd provide it as an example.)

This is basically a ready-rolled (and more general-purpose) form of mquander's solution.

Upvotes: 34

Adriaan Stander
Adriaan Stander

Reputation: 166546

For your example you can try

DateTime StartDate = new DateTime(2009, 3, 10);
DateTime EndDate = new DateTime(2009, 3, 26);
int DayInterval = 3;

List<DateTime> dateList = new List<DateTime>();
while (StartDate.AddDays(DayInterval) <= EndDate)
{
   StartDate = StartDate.AddDays(DayInterval);
   dateList.Add(StartDate);
}

Upvotes: 26

mqp
mqp

Reputation: 72015

Well, you'll need to loop over them one way or the other. I prefer defining a method like this:

public IEnumerable<DateTime> EachDay(DateTime from, DateTime thru)
{
    for(var day = from.Date; day.Date <= thru.Date; day = day.AddDays(1))
        yield return day;
}

Then you can use it like this:

foreach (DateTime day in EachDay(StartDate, EndDate))
    // print it or whatever

In this manner you could hit every other day, every third day, only weekdays, etc. For example, to return every third day starting with the "start" date, you could just call AddDays(3) in the loop instead of AddDays(1).

Upvotes: 603

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