[c#] Datetime in C# add days

I want to add days in some date. I have a code like this:

DateTime endDate = Convert.ToDateTime(this.txtStartDate.Text); 
Int64 addedDays = Convert.ToInt64(txtDaysSupp.Text); 
endDate.AddDays(addedDays); 
DateTime end = endDate; 
this.txtEndDate.Text = end.ToShortDateString();

But this code is not working, days are not added! What the stupid mistake I'm doing?

Use this:

DateTime dateTime =  DateTime.Now;
DateTime? newDateTime = null;
TimeSpan numberOfDays = new TimeSpan(2, 0, 0, 0, 0);
newDateTime = dateTime.Add(numberOfDays);

Its because the AddDays() method returns a new DateTime, that you are not assigning or using anywhere.

Example of use:

DateTime newDate = endDate.AddDays(2);

You can add days to a date like this:

// add days to current **DateTime**
var addedDateTime = DateTime.Now.AddDays(10);

// add days to current **Date**
var addedDate = DateTime.Now.Date.AddDays(10);

// add days to any DateTime variable
var addedDateTime = anyDate.AddDay(10);

Why do you use Int64? AddDays demands a double-value to be added. Then you'll need to use the return-value of AddDays. See here.

You need to catch the return value.

The DateTime.AddDays method returns an object who's value is the sum of the date and time of the instance and the added value.

endDate = endDate.AddDays(addedDays);

Assign the enddate to some date variable because AddDays method returns new Datetime as the result..

Datetime somedate=endDate.AddDays(2);