CODEWITHSUNDEEP
c#linqdatetime
silhouette hustler
silhouette hustler

Reputation: 1763

How to get dates between two dates in C#

I would like to get dates between two dates. Instead of expected 9 different dates, I get 875287 and run out of memory. What would be the problem with the code below?

StartDate value is 01/04/2016 00:00:00

EndDate value is 10/04/2016 00:00:00

var selectedDates = new List<DateTime?>();

for (var date = StartDate; date <= EndDate; date.Value.AddDays(1))
{
    selectedDates.Add(date);
}

Upvotes: 26

Views: 25889

Answers (5)

DoctorMick
DoctorMick

Reputation: 6793

You aren't assigning the value of date.Value.AddDays(1) to anything, so it ends up in an infinite loop. You'd need to change your code so that date is set to the result of AddDays.

for (var date = StartDate; date <= EndDate; date = date.AddDays(1))
{
    selectedDates.Add(date);
}

Upvotes: 42

jessehouwing
jessehouwing

Reputation: 114461

A shorter notation using Linq's Range method uses the ability to already figure out the number of days using the TimeSpan.Days property after subtracting start from end.

Assuming the start is before end you'd end up with:

DateTime StartDate = new DateTime(1979, 10, 4);
DateTime EndDate = new DateTime(2016, 10, 4);

var dates = Enumerable.Range(0, (EndDate - StartDate).Days + 1)
    .Select(day => StartDate.AddDays(day))

If you need it to be Nullable, add:

    .Cast<DateTime?>()

If you need this to be a List, add:

    .ToList()

It's probably quite a bit more efficient than the other LINQ based solution.

Upvotes: 7

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186668

LINQ solution (let's generate selectedDates):

  var selectedDates = Enumerable
    .Range(0, int.MaxValue)
    .Select(index => new DateTime?(StartDate.AddDays(index)))
    .TakeWhile(date => date <= EndDate)
    .ToList();

Upvotes: 32

Soner G&#246;n&#252;l
Soner G&#246;n&#252;l

Reputation: 98740

As far as I can see, since AddDays method returns a new instance of a DateTime, it does not change the current instance since DateTime is immutable.

Looks like your date is DateTime?, you can change this part as;

for (var date = StartDate; date <= EndDate; date = date.Value.AddDays(1))
{
    selectedDates.Add(date);
}

As usr pointed, this might be affected on DST. You might wanna check Dmitry's answer as well.

Upvotes: 12

CathalMF
CathalMF

Reputation: 10055

Decided to change it up with a do/while

var selectedDates = new List<DateTime?>();
DateTime? StartDate = DateTime.Parse("01/04/2016 00:00:00");
DateTime? EndDate = DateTime.Parse("10/04/2016 00:00:00");

do
{
    selectedDates.Add(StartDate);
    StartDate = StartDate.Value.AddDays(1);
}while(StartDate < EndDate);

Upvotes: 1

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