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Adding days to only date and then subtracting it from date in c#

I know this topic has already been discussed but I want to add days to only date, not the complete datetime and then I need to subtract it with date. What I have done till now is :
string endDate = DateTime.Now.AddDays(2).ToShortDateString();
Now this gives me string like 19-jan-17 which is great but when I want to subtract it with todays date, it gives error because the end date is in string. I tried below code:
TimeSpan diff = DateTime.Now.ToShortDateString() - endDate ;
or
TimeSpan diff = DateTime.Now.ToShortDateString() - Convert.ToDateTime(endDate)
or
TimeSpan diff = DateTime.Now.ToShortDateString() - Convert.ToString(endDate)
and if I change DateTime.Now.ToShortDateString() to DateTime.Now then it will also include time which I do not want. I just want to add days in date only and then subtract it with today's date.
Any suggestions. Please help.

Try this:
DateTime endDate = DateTime.Today.AddDays(2);
TimeSpan diff = DateTime.Today - endDate
The Today property will return only the date part (so time will be 00:00:00), but still in a DateTime struct, so you can get a TimeSpan from subtracting another DateTime from it.

Did you try doing the following?
string endDate = DateTime.Now.Date.AddDays(2);
Still, it is not clear why you have to do that. A bit of context would be great for proposing other solutions.

I join Federico, you need to use the Date property of the DateTime instance. It will return the 00:00:00 moment of the date.
One side note:
Just keep all dates in DateTime (e.g. do not convert them into strings) before calculating the diff.
e.g.:
TimeSpan diff = DateTime.Now.Date - endDate;
If you need the date part, you can use format strings after the calculation.
e.g.:
endDate.ToString("yyyy.MM.dd")

How to Convert Long format Date to Short format Date with Type DateTime in C#

I want convert long dateTime to only date in C#. and both in dateTime type
DateTime creationDate = DateTime.Now;
DateTime shortDate = creeationDate.Date;

A DateTime is a struct, which always has -- as the name suggests -- date and time components. You cannot remove the time and there is, as far as I know, no built-in date-only type in .NET (maybe there is in some 3rd party libraries).
You have already discovered the Date property of DateTime which returns an new DateTime with the time components set to 00:00:00.000.
If you only need to output your current date you must apply some formatting on the DateTime
DateTime creationDate = DateTime.Now;
string shortDate = creatationDate.ToString("yyyy-MM-dd"); //or whatever formatting you need.
If you need calculations on your date, but want to ignore the time component, you could initialize your date accordingly, as you have done in your code.
DateTime creationDate = DateTime.Now.Date; //sets time component to 00:00
DateTime otherDate = new DateTime(2016, 11, 2, 0,0,0); //also initializies with time 00:00
int diff = (int)(otherDate-creationDate).TotalDays; //number of days between the two dates

Get Current DateTime C# without hour

Hi I currently have a TimePicker. It returns an object TimeSpan.
What I need to do is to set a DateTimeOffset that is equal to current date plus the TimeSpan from the TimePicker.
How can I actually get the current DateTimeOffset.now that doesn't have a Time on it, only the Date so that I can add the offset to it.
Thanks

As in DateTime object you have a Date property, it returns date part without time (it means time is 00:00:00).
DateTime today = DateTimeOffset.Now.Date;
DateTime result = today + yourTimeSpan;
With this solution will lost Offset information (because Date is a DateTime). To keep it you just need to subtract time part:
DateTimeOffset now = DateTimeOffset.Now;
DateTimeOffset result = now - now.Time + yourTimeSpan;
Or with constructor:
DateTimeOffset now = DateTimeOffset.Now;
DateTimeOffset result = new DateTimeOffset(now.Date + yourTimeSpan, now.Offset);

Can you not just .Date it?
var a = DateTimeOffset.Now.Date;

try using:
DateTime.Today
instead of Now.

Return day Name in c#

I want to return the name of day like Saturday or Monday
I used this code :
DateTime date = new DateTime(DateTime.Now.Date.Day);
MessageBox.Show(date.DayOfWeek.ToString());
But it doesn't work it return the name of day but doesn't correct day
and when i change the date in my computer it still return the same day

Rather try something like
MessageBox.Show(DateTime.Today.DayOfWeek.ToString());
DateTime.Today Property
Gets the current date.
Your problem is that
DateTime date = new DateTime(DateTime.Now.Date.Day);
evaluates to
{01/Jan/0001 12:00:00 AM}
The constructor you used was DateTime Constructor (Int64)
Initializes a new instance of the DateTime structure to a specified
number of ticks.

This line:
DateTime date = new DateTime(DateTime.Now.Date.Day)
Should be:
DateTime date = new DateTime(DateTime.Now)
You are putting the day in a date variable which will probably be in the year 1900.

Join Date and Time to DateTime in C#

I am retrieving data from an iSeries where there is a separate date and time fields. I want to join them into a DateTime field in my C# project. I don't see a way to add just a time to a DateTime field. How would you suggest accomplishing this?

You can do this quite easily:
DateTime dateOnly;
DateTime timeOnly;
...
DateTime combined = dateOnly.Date.Add(timeOnly.TimeOfDay);
TimeOfDay returns a TimeSpan, which you then add to the date.
Edit (thanks to commenters below) - to be safe, use dateOnly.Date to ensure the date part only.

How are they being stored? Assuming that the date portion is being stored as a DateTime of midnight of the day in question and the time is a TimeSpan, you can just add them.
DateTime date = ...;
TimeSpan time = ...;
DateTime result = date + time;

You could easily construct a TimeSpan from your "time" field.
Once you have that, just do:
TimeSpan time = GetTimeFieldData();
dateField = dateField.Add(time);

Datetime date = new DateTime(Date1.Year, Date1.Month, Date1.Day, Time1.Hour, Time1.Minute, Time1.Second);

You can add a TimeSpan to a DateTime and write something like this.
// inside consuming function
ISeriesObject obj = getMyObject();
DateTime dt = getDate(obj) + getTime(obj);
private DateTime getDate(ISeriesObject obj)
{
//return a DateTime
}
private TimeSpan getTime(ISeriesObject obj)
{
//return a TimeSpan
}

My answer addresses joining two objects of DateOnly and TimeOnly in .NET 6:
DateOnly orderDate = ...
TimeOnly orderTime = ...
DateTime orderDateTime = orderDate.ToDateTime(orderTime);

This should do:
var output = date.Date + time.TimeOfDay;
or
var output = new DateTime(date.Year, date.Month, date.Day,
time.Hour, time.Minute, time.Second);
suppose that both variable date and time are both of Type DateTime

Note that adding the time to the date is not your biggest problem here. As #Reed Copsey mentioned, you just create a DateTime from the date and then .Add the time.
However, you need to make sure that the iSeries date and time (a Unix time most probably) are in the same representation as the .Net representation. Thus, you most probably need to convert it by adding it to a Jan 1, 1970 DateTime as well.

Cant you simply format the date part and time part as separate strings, then join them together? Then you can parse the string back to a DateTime object