Looking for a better way to compare a nullable date time than the following:
Any suggestions?
// myobject.ExpireDatetime is of DateTime? // if (!myobject.ExpireDateTime.IsNull() && DateTime.Compare((DateTime)myobject.ExpireDateTime, DateTime.Now.ToUniversalTime()) < 0) { //error! }
Edited: Sorry for confusion...myobject.ExpireDatetime is of type DateTime.
DateTime CAN be compared to null; It cannot hold null value, thus the comparison will always be false. DateTime is a "Value Type". Basically a "value type" can't set to NULL. But by making them to "Nullable" type, We can set to null.
Is it possible to set datetime object to null in C#? DateTime is a Value Type like int, double etc. so there is no way to assigned a null value.
Inserting a null value to the DateTime Field in SQL Server is one of the most common issues giving various errors. Even if one enters null values the value in the database is some default value as 1/1/1900 12:00:00 AM.
Your question is not quite clear to me, but if we have
DateTime? ExpireDateTime; // could be a variable or a property
it's OK to say just
if (ExpireDateTime < DateTime.UtcNow) { ... }
This will be OK if ExpireDateTime
is null
(HasValue
is false). Some inexperienced developers will struggle to understand lifted operators, so to make it more clear, you could write
if (ExpireDateTime < (DateTime?)DateTime.UtcNow) { ... }
It's the same, but easier to read and understand.
Never write .Value
if the nullable might be null, of course. You will get an InvalidOperationException
"Nullable object must have a value" if you do so.
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