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);
}
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);
}
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();
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.
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.
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);
Related
I have two textboxes and a button, both textbox have calender attach to them. I want to store the dates which are between the first textbox and second textbox in a list, I am invoking following method on button click.
private void CollectDates()
{
DateTime StartDate = Convert.ToDateTime(txtFromDate.Text);
DateTime EndDate = Convert.ToDateTime(txtTillDate.Text);
List<DateTime> datelist = new List<DateTime>();
for (StartDate = Convert.ToDateTime(txtFromDate.Text); StartDate < Convert.ToDateTime(txtTillDate.Text); StartDate.AddDays(1))
{
datelist.Add(StartDate);
}
}
But I am getting error after storing the first date in the list: Exception of type 'System.OutOfMemoryException' was thrown.
I think my loop is running endlessly, any help will be appreciated.
DateTime.AddDays() does not change the datetime you must assign its return value. Like
StartDate = StartDate.AddDays(1)
It is indeed an infinite loop. You're stating that if the start date is less than the end date, add start date to the list. It'll keep doing this for infinity as start date should always (in theory) be less than the end date. The add days function isn't assigned to a variable so it never gets added to the start date.
Also another piece of advice with .Net datetime is to use the in-built compare function.
DateTime Compare function
Hope that helps!
Try this:
private void CollectDates()
{
DateTime StartDate = Convert.ToDateTime(txtFromDate.Text);
DateTime EndDate = Convert.ToDateTime(txtTillDate.Text);
List<DateTime> dateList = new List<DateTime>();
DateTime currentDate = StartDate;
while(currentDate <= EndDate)
{
dateList.Add(currentDate);
currentDate.AddDays(1);
}
}
use this
for (int i =0; i<(EndDate-StartDate).Days; i++)
{
datelist.Add(StartDate.AddDays(i));
}
you might want to try linq:
Enumerable.Range(0, (int)endDate.Subtract(startDate).TotalDays)
.Select(d => startDate.AddDays(d))
.ToList()
I have two dates:
DateTime fromDate = new DateTime(2013,7,27,12,0,0);
DateTime toDate = new DateTime(2013,7,30,12,0,0);
I want to iterate from fromDate to toDate by incrementing fromDate with a single day and the loop should break when fromDate becomes equal to or greater than the toDate. I have tried this:
while(fromDate < toDate)
{
fromDate.AddDays(1);
}
But this is an infinite loop and won't stop. How can I do this ?
Untested but should work:
for(DateTime date = fromDate; date < toDate; date = date.AddDays(1)) {
}
Modify the comparison to <= if you want to include toDate as well.
DateTime.AddDays indeed adds the specified number of days to the date - but the resulting date is returned as a new DateTime value; the original DateTime value is not changed.
Therefore, make sure you assign the result of the your operation back to the variable you inspect in your loop condition:
while (fromDate < toDate)
{
fromDate = fromDate.AddDays(1);
}
How can i get list of dates between start and end dates using linq or lambda expression.
DateTime StartDate = DateTime.Now;
DateTime EndDate = DateTime.Now.AddMonths(13);
List<DateTime> ListofDates = //Contains list of all dates only between start and end date.
Enumerable.Range(0, (EndDate - StartDate).Days).Select(i => StartDate.AddDays(i))
First of all, when you want Dates and not Datetimes you better use DateTime.Now.Date instead of just DateTime.Now
I've edited SLaks code so you can get the list of dates you want.
DateTime StartDate = DateTime.Now.Date;
DateTime EndDate = DateTime.Now.Date.AddMonths(13);
IEnumerable<double> daysToAdd = Enumerable.Range(0,
(EndDate - StartDate).Days + 1)
.ToList().ConvertAll(d => (double)d);
IEnumerable<DateTime> ListOfDates = daysToAdd.Select(StartDate.AddDays).ToList();
Note that I've added +1 in the enumerable so you can have both the start and end date (you didn't specify it)
List<DateTime> ListofDates = Enumerable.Range(0, (EndDate - StartDate).Days)
.Select(i => StartDate.AddDays(i))
.ToList();
I need to find the difference in days between two dates.
For example:
Input: **startDate** = 12-31-2012 23hr:59mn:00sec, **endDate** = 01-01-2013 00hr:15mn:00sec
Expected output: 1
I tried the following:
(dt1-dt2).TotalDays and convert to integer but didn't give me appropriate answer as double has to be converted to int - tried Math.Ceiling, Convert.To...
dt1.day - dt2.day does not work across months
dt.Substract() has the same output as option 1 mentioned above.
None of the above worked, so I ended up writing the following code. The code works well, but I feel that there must be a solution with only a couple of lines of code.
public static int GetDifferenceInDaysX(this DateTime startDate, DateTime endDate)
{
//Initializing with 0 as default return value
int difference = 0;
//If either of the dates are not set then return 0 instead of throwing an exception
if (startDate == default(DateTime) | endDate == default(DateTime))
return difference;
//If the dates are same then return 0
if (startDate.ToShortDateString() == endDate.ToShortDateString())
return difference;
//startDate moving towards endDate either with increment or decrement
while (startDate.AddDays(difference).ToShortDateString() != endDate.ToShortDateString())
{
difference = (startDate < endDate) ? ++difference : --difference;
}
return difference;
}
Note: I do not have any performance issue in the while-loop iteration as the max difference will not be more than 30 to 45 days.
Well, it sounds like you want the difference in the number of days, ignoring the time component. A DateTime with the time component reset to 00:00:00 is what the Date property gives you:
(startDate.Date - endDate.Date).TotalDays
If you use the DateTime.Date property this will eliminate the time
date1.Date.Subtract(date2.Date).Days
Use TimeStamp. Just subtract two dates (using DateTime.Date property), get the difference in time span and return TotalDays
TimeSpan ts = endDate.Date - startDate.Date;
double TotalDays = ts.TotalDays;
So your extension method can be as simple as:
public static int GetDifferenceInDaysX(this DateTime startDate, DateTime endDate)
{
return (int) (endDate.Date - startDate.Date).TotalDays;
// to return just a int part of the Total days, you may round it according to your requirement
}
EDIT: Since the question has been edited, you may check the following example.
Consider the following two dates.
DateTime startDate = new DateTime(2012, 12, 31, 23, 59, 00);
DateTime endDate = new DateTime(2013, 01, 01, 00, 15, 00);
You can write the extension method as:
public static int GetDifferenceInDaysX(this DateTime startDate, DateTime endDate)
{
TimeSpan ts = endDate - startDate;
int totalDays = (int) Math.Ceiling(ts.TotalDays);
if (ts.TotalDays < 1 && ts.TotalDays > 0)
totalDays = 1;
else
totalDays = (int) (ts.TotalDays);
return totalDays;
}
For the above dates it will give you 1
This question already has answers here:
How do I loop through a date range?
(17 answers)
Closed 6 years ago.
I have a DateTime StartDate and EndDate.
How can I, irrespective of times, iterate across each Day between those two?
Example: StartDate is 7/20/2010 5:10:32 PM and EndDate is 7/29/2010
1:59:12 AM.
I want to be able to iterate across 7/20, 7/21, 7/22 .. 7/29.
for(DateTime date = StartDate; date.Date <= EndDate.Date; date = date.AddDays(1))
{
...
}
The .Date is to make sure you have that last day, like in the example.
An alternative method that might be more reusable is to write an extension method on DateTime and return an IEnumerable.
For example, you can define a class:
public static class MyExtensions
{
public static IEnumerable EachDay(this DateTime start, DateTime end)
{
// Remove time info from start date (we only care about day).
DateTime currentDay = new DateTime(start.Year, start.Month, start.Day);
while (currentDay <= end)
{
yield return currentDay;
currentDay = currentDay.AddDays(1);
}
}
}
Now in the calling code you can do the following:
DateTime start = DateTime.Now;
DateTime end = start.AddDays(20);
foreach (var day in start.EachDay(end))
{
...
}
Another advantage to this approach is that it makes it trivial to add EachWeek, EachMonth etc. These will then all be accessible on DateTime.
You have to be careful about end-date. For example, in
Example: StartDate is 7/20/2010 5:10:32 PM and EndDate is 7/29/2010 1:59:12 AM.
I want to be able to iterate across 7/20, 7/21, 7/22 .. 7/29.
date < endDate will not include 7/29 ever. When you add 1 day to 7/28 5:10 PM - it becomes 7/29 5:10 PM which is higher than 7/29 2 AM.
If that is not what you want then I'd say you do
for (DateTime date = start.Date; date <= end.Date; date += TimeSpan.FromDays(1))
{
Console.WriteLine(date.ToString());
}
or something to that effect.
The loops of #Yuriy Faktorovich, #healsjnr and #mho will all throw a System.ArgumentOutOfRangeException: The added or subtracted value results in an un-representable DateTime
exception if EndDate == DateTime.MaxValue.
To prevent this, add an extra check at the end of the loop
for(DateTime date = StartDate; date.Date <= EndDate.Date; date = date.AddDays(1))
{
...
if (date.Date == DateTime.MaxValue.Date)
{
break;
}
}
(I would have posted this as a comment to #Yuriy Faktorovich's answer, but I lack reputation)
DateTime date = DateTime.Now;
DateTime endDate = date.AddDays(10);
while (date < endDate)
{
Console.WriteLine(date);
date = date.AddDays(1);
}