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Customer date start time

When my application starts I have a datetimepicker for a start time and end time.
dvSubmittedDateBegin.Format = DateTimePickerFormat.Custom;
dvSubmittedDateBegin.CustomFormat = "MMM dd yyyy - hh mm tt";
Everything works. However I've been asked to have the start default default at 5AM.
I created a new datetime and assigned the dvSubmittedDateBegin.Value - dt;
However the new datetime I guess I have to specify every int?
DateTime dt = new DateTime(2015, 6, 24, 05, 00, 0);
What happens tomorrow when its 6/25? Not sure how to fix this.

How about like;
DateTime dt = DateTime.Today + TimeSpan.FromHours(5);
or more simple
DateTime dt = DateTime.Today.AddHours(5);
You will get the current date from midnight with DateTime.Today and you will add 5 hours to it and it will be 5 AM of the current day.

You can use the AddDays(), AddHours(), AddMinutes() etc. methods:
DateTime dt = DateTime.Today.AddHours(5);

You can create a function that would return a particular date where you pass all the components and define time components as default parameters:
DateTime CreateDateWith5amStart(int year, int month, int day, int hour = 5, int minute = 0, int second = 0)
{
return new DateTime(year, month, day, hour, minute, second)
}
If they provide only date components, it will set time to 5 a.m. If they need a different time, they can provide time components.

How to get the previous month date in asp.net

I need to get the previous months date in asp.net which means that if the current date is 5/2/2013 then I want to display the previous date as 5/1/2013. How to solve this?

Try this :
DateTime d = DateTime.Now;
d = d.AddMonths(-1);

The solution is to substract 1 month:
DateTime.Now.AddMonths(-1)
Or if not just build the datetime object from scratch:
var previousDate = DateTime.Now.AddMonth(-1);
var date = new DateTime(previousDate.Year, previousDate.Month, DateTime.Now.Day);
this time you are guaranteed that the year and month are correct and the day stays the same. (although this is not a safe algorithm due to cases like the 30th of march and the previous date should be 28/29th of February, so better go with the first sugeestion of substracting a month)

If you already have date time in string format
var strDate = "5/1/2013";
var dateTime = DateTime.ParseExact(strDate,
"dd/MM/yyyy",
CultureInfo.InvariantCulture);
var lastMonthDateTime = dateTime.AddMonths(-1);
else if you have DateTime object just call it's AddMonths(-1) method.

How to set time to midnight for current day?

Every time that I create a non-nullable datetime in my mvc3 application it defaults to now(), where now is current date with current time. I would like to default it to today's date with 12am as the time.
I'm trying to default the time in my mvc...but...the following isn't setting to todays date #12am. Instead it defaults to now with current date and time.
private DateTime _Begin = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, 12, 0, 0);
public DateTime Begin { get { return _Begin; } set { _Begin = value; } }
How can I set to 12am for the current date for non-nullable datetime?

You can use the Date property of the DateTime object - eg
DateTime midnight = DateTime.Now.Date;
So your code example becomes
private DateTime _Begin = DateTime.Now.Date;
public DateTime Begin { get { return _Begin; } set { _Begin = value; } }
PS. going back to your original code setting the hours to 12 will give you time of noon for the current day, so instead you could have used 0...
var now = DateTime.Now;
new DateTime(now.Year, now.Month, now.Day, 0, 0, 0);

I believe you are looking for DateTime.Today. The documentation states:
An object that is set to today's date, with the time component set to 00:00:00.
http://msdn.microsoft.com/en-us/library/system.datetime.today.aspx
Your code would be
DateTime _Begin = DateTime.Today;

Using some of the above recommendations, the following function and code is working for search a date range:
Set date with the time component set to 00:00:00
public static DateTime GetDateZeroTime(DateTime date)
{
return new DateTime(date.Year, date.Month, date.Day, 0, 0, 0);
}
Usage
var modifieddatebegin = Tools.Utilities.GetDateZeroTime(form.modifieddatebegin);
var modifieddateend = Tools.Utilities.GetDateZeroTime(form.modifieddateend.AddDays(1));

Only need to set it to
DateTime.Now.Date
Console.WriteLine(DateTime.Now.Date.ToString("yyyy-MM-dd HH:mm:ss"));
Console.Read();
It shows
"2017-04-08 00:00:00"
on my machine.

Related, so I thought I would post for others. If you want to find the UTC of the start of today (for your timezone) the following code works for any UTC offset (-23.5 thru +23.5). This looks like we add X hours then subtract X hours, but the important thing is the ".Date" after the add.
double utcOffset= 10.0; // Set to your UTC offset in hours (eg. Melbourne Australia)
var now = DateTime.UtcNow;
var startOfToday = now.AddHours(utcOffset - 24.0).Date;
startOfToday = startOfToday.AddHours(24.0 - utcOffset);

Most of the suggested solutions can cause a 1 day error depending on the time associated with each date. If you are looking for an integer number of calendar days between to dates, regardless of the time associated with each date, I have found that this works well:
return (dateOne.Value.Date - dateTwo.Value.Date).Days;

Try this:
DateTime Date = DateTime.Now.AddHours(-DateTime.Now.Hour).AddMinutes(-DateTime.Now.Minute)
.AddSeconds(-DateTime.Now.Second);
Output will be like:
07/29/2015 00:00:00

Assign datetime value to today's date with specific time

I have a variable which is defined as a DateTime. I need to assign it today's date but have the time be 4 PM. How do I do this?

You want DateTime.Today.AddHours(16)
DateTime.Today will return today's date at midnight.
You can also use the Date property to drop the time from an arbitrary DateTime value.

I think this should do what you need...
DateTime today = DateTime.Today;
DateTime dt = new DateTime(today.Year, today.Month, today.Day, 16, 0, 0);

var anotherTime = DateTime.Today.AddHours(16.0);

Take a look at all the overloaded constructors for DateTime.
DateTime myDate = new DateTime(DateTime.Today.Year, DateTime.Today.Month, DateTime.Today.Day, 16, 0, 0);
Edit: Correction. Thanks Jon. :)

How to set only time part of a DateTime variable in C# [duplicate]

This question already has answers here:
How to change time in DateTime?
(29 answers)
Closed 9 years ago.
I have a DateTime variable:
DateTime date = DateTime.Now;
I want to change the time part of a DateTime variable. But when I tried to access time part (hh:mm:ss) these fields are readonly.
Can't I set these properties?

Use the constructor that allows you to specify the year, month, day, hours, minutes, and seconds:
var dateNow = DateTime.Now;
var date = new DateTime(dateNow.Year, dateNow.Month, dateNow.Day, 4, 5, 6);

you can't change the DateTime object, it's immutable. However, you can set it to a new value, for example:
var newDate = oldDate.Date + new TimeSpan(11, 30, 55);

date = new DateTime(date.year, date.month, date.day, HH, MM, SS);

I'm not sure exactly what you're trying to do but
you can set the date/time to exactly what you want in a number of ways...
You can specify 12/25/2010 4:58 PM by using
DateTime myDate = Convert.ToDateTime("2010-12-25 16:58:00");
OR if you have an existing datetime construct , say 12/25/2010 (and any random time) and you want to set it to 12/25/2010 4:58 PM, you could do so like this:
DateTime myDate = ExistingTime.Date.AddHours(16).AddMinutes(58);
The ExistingTime.Date will be 12/25 at midnight, and you just add hours and minutes to get it to the time you want.

It isn't possible as DateTime is immutable. The same discussion is available here: How to change time in datetime?