comparing nullables

[STech]

What is the recommended way for comparing two nullabe DateTime types using
the CompareTo method.

DateTime? d1
DateTime? d2

return d1.Value.CompareTo(d2.Value) //This obvoiusly will fail if one is null

return d1.GetDefaultOrValue().CompareTo(d2.GetDefaultOrVa lue()) //this works
but it is a hack as you are converting a null type to DateTime.MinValue and
then doing a compare.

I wish to return
-1 if d1 < d2,
0 if d1 = d2,
1 if d1 > d2

Thanks

[Jeff Louie]

In many classes Compare is often implemented as a static method for null
behaviour. I see a static DateTime.Compare(t1,t2) method, but I have not
tried
it.

Regards,
Jeff

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[Nicholas Paldino [.NET/C# MVP]]

STech,

You can always use the static Compare<T> method on the Nullable class,
like so:

DateTime? d1;
DateTime? d2;

return Nullable.Compare(d1, d2);

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"STech" <st***@nospam.nospam> wrote in message
news:C7**********************************@microsof t.com...

What is the recommended way for comparing two nullabe DateTime types using
the CompareTo method.

DateTime? d1
DateTime? d2

return d1.Value.CompareTo(d2.Value) //This obvoiusly will fail if one is
null

return d1.GetDefaultOrValue().CompareTo(d2.GetDefaultOrVa lue()) //this
works
but it is a hack as you are converting a null type to DateTime.MinValue
and
then doing a compare.

I wish to return
-1 if d1 < d2,
0 if d1 = d2,
1 if d1 > d2

Thanks

[TerryFei]

Hi,
Welcome to MSDN Newsgroup!

We could write one method to compare the DateTime. At .Net 2.0, the
Nullable structure could be used for this scenario. The parameter type of
this method could be DateTime?.
//-------------------------------
static int CompareDT(DateTime? dt1, DateTime? dt2)
{
if (dt1.HasValue && dt2.HasValue)
return dt1.Value.CompareTo(dt2.Value);
else
return -2; //custom error code
}
//----------------------------------
If dt1 or dt2 is a null value, we should return error code, which assured
that there's no exception will be thrown and this snippet code will always
work.

I hope the above information is useful for you. If you have any questions
or concerns, please feel free to let me know. :)

Best Regards,

Terry Fei[MSFT]
Microsoft Community Support
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