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C# How to convert date local to UTC with time 00:00:00 and 23:59:59?

I have a stored procedure which returns data between date range. I am sending Start Date and End Date as parameters after converting those dates into UTC. I am facing difficulty due to time span.
For example:
StartDate: 2019-08-05T06:11:02.676Z
EndDate: 2019-08-05T06:11:02.676Z
I can not get data for the day 5th of August.
For that I need datetime format like,
StartDate: 2019-08-05T00:00:00
EndDate: 2019-08-05T23:59:59
Please help me to derive above datetime format.

You can use DateTime.Now.Date() to get only Date and compare only dates.
var dateAndTime = DateTime.Now;
var date = dateAndTime.Date;

Just create two DateTimes objects with the time set, for example:
var now = DateTime.Now();
var startDate = new DateTime(now.Year, now.Month, now.Day, 0, 0, 0);
var endDate = new DateTime(now.Year, now.Month, now.Day, 23, 59, 59);

How to create a future date having known the month and year

I have to calculate the date or create a date which is 10 days into next month. I have with me month and year. If the month is April and year is 2019 I need a date which is 10th of may 2019.

You can simply use the methods available in the DateTime structure to do math with dates
// As example, replaces it with whatever date you have
DateTime current = new DateTime(2019,4,5);
DateTime next = new DateTime(current.Year, current.Month, 1).AddMonths(1).AddDays(9);

You can use AddMonths() and AddDays() extension method of DateTime.
From MSDN :
AddMonths() : Returns a new DateTime that adds the specified number of
months to the value of this instance.
AddDays() : Returns a new DateTime that adds the specified number of
days to the value of this instance.
//Considered this is your Current date
DateTime existingDate = new DateTime(2019, 4, 1);
//Below code will add +1 month to current month and +9 days to current date.
var result = existingDate.AddMonths(1).AddDays(9);
Output :
CurrentDate : 4/1/2019 12:00:00 AM
Next Date (+1 month and +9 days) :5/10/2019 12:00:00 AM
POC : .net Fiddle

var dateNow = DateTime.Now.AddMonths(1);
var date = new DateTime(dateNow.Year, dateNow.Month, 10);

Try this:
DateTime dt = new DateTime(2019, 04, 01);
DateTime newDT = dt.AddMonths(1).AddDays(9);

Get the days of year and all the hours between 2 dates in C#

I have folder structures like Year (2016)->day of year (308,309) -> hour in the day (00 to 23). I want to know how to get all the days and hours between 2 dates say between today 9am and yesterday 10am. Is there an easy way to do this?
My bad! I didn't give enough information. So I did try Span before I asked this and I don't want to get the different like the span.days, hours or mins instead i want the days of the year and hours between 2 dates.
like between yesterday 10 am and today it will 307th day 10th hour,11th hour and so on... until today 308th day and 9th hour. I can do this by looping thru the dates but i wanted to know if there is a straight forward way.

I would create a simple class for storing the data you need:
class DateInfo
{
public string Year {get;set;}
public string DayOfYear{get;set;}
public string Hour {get;set;}
}
and then get the results:
DateTime d1 = DateTime.Today.AddDays(-1).AddHours(10);
DateTime d2 = DateTime.Today.AddHours(9);
IList<DateInfo> dates = new List<DateInfo>();
while (d1 <= d2)
{
DateInfo dateInfo = new DateInfo()
{
Year = d1.ToString("yyyy"),
DayOfYear = d1.DayOfYear.ToString(),
Hour = d1.ToString("HH"),
};
dates.Add(dateInfo);
d1 = d1.AddHours(1);
}

There would be n number of ways to find out the difference between two dates. 2 of them are as follows
DateTime a = new DateTime(2016, 11, 03, 10, 00, 00);
DateTime b = DateTime.Now;
Console.WriteLine(b.Subtract(a).TotalHours);
This will give you the total hours between two dates Where as
TimeSpan span = (b - a);
Console.WriteLine(String.Format("{0} days, {1} hours, {2} minutes, {3} seconds", span.Days, span.Hours, span.Minutes, span.Seconds));
This will give you the details in the format which everyone can understand.

how to subtract previous date from current date using c# [duplicate]

This question already has answers here:
C#: how do I subtract two dates?
(11 answers)
Closed 10 years ago.
i want to subtract previous date from current date. previous date may be 2 months and 15 days or 1 year 9 month and 10 days... like this etc... So please how can i write the Coding in C#. thanks a lot.

Any answer using TimeSpan will not be able to give you "2 months and 15 days" - as the length of a month changes over time.
Doing this using the base class libraries is a pain... which is one of the reasons I started the Noda Time project. Amongst its other features, it allows you to determine the Period between to dates (or dates and times, etc).
For example, let's see how long I've been on Stack Overflow:
LocalDate today = new LocalDate(2013, 2, 8);
LocalDate start = new LocalDate(2008, 9, 26);
// This defaults to using year, month, day units. You can specify alternatives.
Period period = Period.Between(start, today);
Console.WriteLine("{0} years; {1} months; {2} days",
period.Years, period.Months, period.Days);
Output:
4 years; 4 months; 13 days
Or if you actually wanted to subtract a period from a date (the question isn't very clear) you can do that too:
Period period = new PeriodBuilder { Years = 4, Months = 4, Days = 13 }.Build();
LocalDate today = new LocalDate(2013, 2, 8);
LocalDate start = today - period;
Console.WriteLine(start);
Output:
25 September 2008
Note that this doesn't give September 26th, because of the somewhat crazy nature of date/time arithmetic. If you added the period to September 26th you'd get today... but that's not the same thing. Treat this as a warning that you need to be really careful about describing what you want to achieve :)
This second side you can do with the BCL fairly easily though:
DateTime today = new DateTime(2013, 2, 8);
DateTime start = today.PlusYears(-4).PlusMonths(-4).PlusDays(-13);
There's no BCL type to represent that "years, months, days" value though.

Your question is a little confusing. Do you want to subtract one date from another date, or do you want to subtract a period of time from a date.
1. Subtract one date from another date:
DateTime previousDate = new DateTime(1990, 12, 12);
DateTime currentDate = DateTime.UtcNow;
TimeSpan difference = currentDate - previousDate;
You can then use the TimeSpan methods to get the difference in various units of time as you like.
Here's more info on TimeSpan: http://msdn.microsoft.com/en-us/library/system.timespan.aspx
2. Subtract a period of time from a date
DateTime currentDate = DateTime.UtcNow;
TimeSpan periodOfTime = new TimeSpan(12, 12, 0, 0);
DateTime newDate = currentDate - periodOfTime;
However, you'll have to calculate yourself what the length of a month is, if that's what you want.

You can use DateTime.Subtract.
Examples from article:
System.DateTime date1 = new System.DateTime(1996, 6, 3, 22, 15, 0);
System.DateTime date2 = new System.DateTime(1996, 12, 6, 13, 2, 0);
System.DateTime date3 = new System.DateTime(1996, 10, 12, 8, 42, 0);
// diff1 gets 185 days, 14 hours, and 47 minutes.
System.TimeSpan diff1 = date2.Subtract(date1);
// date4 gets 4/9/1996 5:55:00 PM.
System.DateTime date4 = date3.Subtract(diff1);
// diff2 gets 55 days 4 hours and 20 minutes.
System.TimeSpan diff2 = date2 - date3;
// date5 gets 4/9/1996 5:55:00 PM.
System.DateTime date5 = date1 - diff2;

TimeSpan timeSpan = new TimeSpan(2,2,0);
DateTime dateTime = DateTime.Now.Subtract(timeSpan);

When you subtract two date in C# you get a TimeSpan object.
You can acces different properties of it to get the actual days, hours, minutes etc. taht it represents:
DateTime a;
DateTime b;
//assign some values
TimeSpan span = a.Subtract(b);
Console.WriteLine("Days: " + span.Days);

The following should do.
TimeSpan diff = DateTime.Now - previousDate;

subtract 2 datetime fields to get the days left difference

Would appreciate it if anyone can help me figure out to substract 2 datetime fields to get the days left difference.

This is very easy to do with C#. For comparing DateTimes, we have a class called TimeSpan. The TimeSpan structure, in this case, would be defined as the difference between your two datetimes.
Let's say that your DateTimes are called start and end.
DateTime start = new DateTime(2009, 6, 14);
DateTime end = new DateTime(2009, 12, 14);
We have established our DateTimes to June 14, 2009 and December 14, 2009.
Now, let's find the difference between the two. To do this, we create a TimeSpan:
TimeSpan difference = end - start;
With this TimeSpan object, you can express the difference in times in many different ways. However, you specifically asked for the difference in days, so here's how you can get that:
Console.WriteLine("Difference in days: " + difference.Days);
Thus, the property is called TimeSpan.Days.
Final Code
//establish DateTimes
DateTime start = new DateTime(2009, 6, 14);
DateTime end = new DateTime(2009, 12, 14);
TimeSpan difference = end - start; //create TimeSpan object
Console.WriteLine("Difference in days: " + difference.Days); //Extract days, write to Console.
For more information on using the TimeSpan structure, see this MSDN documentation (especially the C# examples).
Hope I helped!
UPDATE: Some answers have suggested taking doing subtraction in one step, such as with:
int days = (dt2 - dt1).Days;
or
int numDaysDiff = Math.Abs(date2.Subtract(date1).Days);
However, they are the same thing as in my answer, only shortened. This is because the DateTime.Subtract() method and the subtraction operator of DateTimes returns a TimeSpan, from which you can then access the amount of days. I have specifically used the longer approach in my code sample so that you clearly understand what is going on between your DateTime and TimeSpan objects and how it all works. Of course, the other approaches I just mentioned are fine, too.
UPDATE #2:
A very similar question was asked before, and it can be found here. However, the main point of that question was why the code sample (which is essentially equivalent to that of all the answers) sometimes provides an answer which is a day off. I think this is also important to this question.
As the main answer to the other question suggests, you can use this code:
int days = (int)Math.Ceiling(difference.TotalDays);
This code uses Math.Ceiling, which, according to MSDN, is:
Returns the smallest integral value
that is greater than or equal to the
specified double-precision
floating-point number.
How Do You Want to Count the Days?
Thus, we now have an issue with how you want to count the days. Do you want to count part of a day (such as .5 of a day) as:
A full day - this would use Math.Ceiling to round up TimeSpan.TotalDays, so that you're counting started days.
Part of a day - you can just return the TimeSpan.TotalDays (not rounded) as a decimal (in the double datatype)
Nothing - you can ignore that part of a day and just return the TimeSpan.Days.
Here are code samples for the above:
Counting as a full day (using Math.Ceiling() to round up):
//establish DateTimes
DateTime start = new DateTime(2009, 6, 14);
DateTime end = new DateTime(2009, 12, 14);
TimeSpan difference = end - start; //create TimeSpan object
int days = (int)Math.Ceiling(difference.TotalDays); //Extract days, counting parts of a day as a full day (rounding up).
Console.WriteLine("Difference in days: " + days); //Write to Console.
Counting as part of a day (NOT using Math.Ceiling(), instead leaving in decimal form as a part of a day):
//establish DateTimes
DateTime start = new DateTime(2009, 6, 14);
DateTime end = new DateTime(2009, 12, 14);
TimeSpan difference = end - start; //create TimeSpan object
double days = difference.TotalDays; //Extract days, counting parts of a day as a part of a day (leaving in decimal form).
Console.WriteLine("Difference in days: " + days); //Write to Console.
Counting as nothing of a day (rounding down to the number of full days):
//establish DateTimes
DateTime start = new DateTime(2009, 6, 14);
DateTime end = new DateTime(2009, 12, 14);
TimeSpan difference = end - start; //create TimeSpan object
int days = difference.TotalDays; //Extract days, counting parts of a day as nothing (rounding down).
Console.WriteLine("Difference in days: " + days); //Write to Console.

Use
TimeSpan
DateTime departure = new DateTime(2010, 6, 12, 18, 32, 0);
DateTime arrival = new DateTime(2010, 6, 13, 22, 47, 0);
TimeSpan travelTime = arrival - departure;

The easiest way out is, making use of TimeSpan().
This Subtract function will return you the difference between two dates in terms of time span. Now you can fetch fields like days, months etc. To access days you can make use of
Here is the sample code;
VB.Net code;
Dim tsTimeSpan As TimeSpan
Dim ldDate1 as Date
Dim ldDate2 as Date
'Initialize date variables here
tsTimeSpan = ldDate1 .Subtract(ldDate2)
Dim NumberOfDays as integer = tsTimeSpan.days
C#.Net code;
DateTime lDate1;
DateTime lDate2;
TimeSpan tsTimeSpan ;
int NumberOfDays;
//Initialize date variables here
tsTimeSpan = ldDate1 .Subtract(ldDate2);
NumberOfDays = tsTimeSpan.days;

DateTime dt1 = new DateTime(2009,01,01,00,00,00);
DateTime dt2 = new DateTime(2009,12,31,23,59,59);
int days = (dt2 - dt1).Days;

Number of Days Difference
These answers take the number of days as an int from the System.TimeSpan structure that is the result of subtracting two System.DateTime fields...
Quick answer - gets the number of days difference.
int numDaysDiff = date2.Subtract(date1).Days;
Alternate answer - uses Math.Abs to ensure it's not a negative number, just in case the dates might be supplied in either order.
int numDaysDiff = Math.Abs( date2.Subtract(date1).Days );
Some sample data to finish it off using System namespace:
// sample data
DateTime date1 = DateTime.Now;
DateTime date2 = DateTime.Now.AddDays(10);
MSDN References (and more sample code ):
System.TimeSpan structure
System.DateTime structure
System.Math.Abs(..) method

DateTime theDate = DateTime.Today;
int datediff = theDate.Subtract(expiryDate).Negate().Days;
if expiryDate > theDate then you get Negative value: -14
expiryDate is less than theDate then you get positive value: 14
You May obviously want this in a scenario such as
Send a Notification Email 14days before expiry
Send another notification Email 14 days after expiry
You need a difference that could be negative value

You should look at TimeSpan.

To get the exact days ignoring the time section
DateTime d1 = Convert.ToDateTime(DateTime.Now.ToShortDateString());
DateTime d2 = Convert.ToDateTime(DateTime.Now.AddDays(46).ToShortDateString());
var days = Convert.ToInt32(d2.Subtract(d1).TotalDays)