How can I write
string date = "12/2/2011";
DateTime? dt = date ?? DateTime.Parse(date);
this throws a compile time error. I know I can do tryparse or do if {}. Is there any way to do this in one line?
4 Answers
Try using the conditional operator ?: instead of the null-coalescing operator ??:
DateTime? dt = date == null ? (DateTime?)null : DateTime.Parse(date);
You also need to cast the null to DateTime? otherwise you will get a compile error.
Comments
string date = "12/2/2011";
DateTime? dt = String.IsNullOrEmpty(date) ? (DateTime?)null : DateTime.Parse(date);
Comments
This solution not only assigns null to the nullable DateTime dt when the string date is null or an empty string, but also when it contains an invalid date representation:
string date = null; // or "01/02/2011"
DateTime? dt;
DateTime temp;
if (DateTime.TryParse(date, out temp)) {
dt = temp;
} else {
dt = null;
}
The if-else statement can be replaced by a one line ternary expression, however not the declaration of temp:
DateTime temp;
dt = DateTime.TryParse(date, out temp) ? temp : (DateTime?)null;
answered Dec 1, 2011 at 20:21
Olivier Jacot-Descombes
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3 Comments
Olivier Jacot-Descombes
Downvoter please comment. What is wrong with my solution? It will not only detect when date is null, but also when it does not contain a valid date string. Note also that dt is nullable.
everag
I just see no reason for your
else statement, since dt is null from the start.Olivier Jacot-Descombes
@EvertonAgner: Only if
dt is a member variable, but not if it is a local variable. From the example given in the question, I do not see, whether dt is defined in a class or in a method.string date = "12/2/2011";
date = Convert.ToDateTime(date);
answered Dec 1, 2011 at 20:14
Shankar Narayana Damodaran
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DateTime? dt = date ? DateTime.Parse(date) : null;