How to set DateTime to null

Question

Using C#. I have a string dateTimeEnd.

If the string is in right format, I wish to generate a DateTime and assign it to eventCustom.DateTimeEnd

Answer 1

It looks like you just want:

eventCustom.DateTimeEnd = string.IsNullOrWhiteSpace(dateTimeEnd)
    ? (DateTime?) null
    : DateTime.Parse(dateTimeEnd);

Note that this will throw an exception if dateTimeEnd isn't a valid date.

An alternative would be:

DateTime validValue;
eventCustom.DateTimeEnd = DateTime.TryParse(dateTimeEnd, out validValue)
    ? validValue
    : (DateTime?) null;

That will now set the result to null if dateTimeEnd isn't valid. Note that TryParse handles null as an input with no problems.

Answer 2

You can write DateTime? newdate = null;

Answer 3

Now, I can't use DateTime?, I am using DBNull.Value for all data types. It works great.

eventCustom.DateTimeEnd = string.IsNullOrWhiteSpace(dateTimeEnd)
  ? DBNull.Value
  : DateTime.Parse(dateTimeEnd);

Answer 4

This line:

eventCustom.DateTimeEnd = dateTimeEndResult = true ? (DateTime?)null : dateTimeEndResult;

is same as:

eventCustom.DateTimeEnd = dateTimeEndResult = (true ? (DateTime?)null : dateTimeEndResult);

because the conditional operator ? has a higher precedence than the assignment operator =. That's why you always get null for eventCustom.DateTimeEnd. (MSDN Ref)

Answer 5

This should work:

if (!string.IsNullOrWhiteSpace(dateTimeEnd))
    eventCustom.DateTimeEnd = DateTime.Parse(dateTimeEnd);
else
    eventCustom.DateTimeEnd = null;

Note that this will throw an exception if the string is not in the correct format.

Answer 6

DateTime is a non-nullable value type

DateTime? newdate = null;

You can use a Nullable<DateTime>

c# Nullable Datetime