Hi,
I have a class with several properties, one of which is of the DateTime
datatype. However, this property will not always have a value, and I need to
check later whether it has a value or not.
When I create a new instance of the class, this property acquires a default
value of {1/1/1}, which I don't want at all, as that is a perfectly valid
date.
Is there any way to cause a DateTime datatype to have no value at all, which
I can check later?
Or is the answer not to use a DataTime datatype and use a generic object
datatype instead?
Any assistance gratefully received.
Mark 11 16400
Dates are value types, not reference types, so they can not be null, they
hold always a value. Could you use DateTime.MinValue as a special value to
denote no value?
--
Best regards,
Carlos J. Quintero
MZ-Tools: Productivity add-ins for Visual Studio .NET, VB6, VB5 and VBA
You can code, design and document much faster.
Free resources for add-in developers: http://www.mztools.com
"Mark Rae" <ma**@mark-N-O-S-P-A-M-rae.co.uk> escribió en el mensaje
news:ev**************@TK2MSFTNGP14.phx.gbl... Hi,
I have a class with several properties, one of which is of the DateTime datatype. However, this property will not always have a value, and I need to check later whether it has a value or not.
When I create a new instance of the class, this property acquires a default value of {1/1/1}, which I don't want at all, as that is a perfectly valid date.
Is there any way to cause a DateTime datatype to have no value at all, which I can check later?
Or is the answer not to use a DataTime datatype and use a generic object datatype instead?
Any assistance gratefully received.
Mark
Mark,
In .NET 2.0, you would use the Nullable<T>, with the type parameter T
equal to DateTime. This will produce a structure which has a HasValue
property which is true if there is a value, false if it is null.
If you are using a version of .NET before 2.0, then you could use the
SqlDateTime, which supports null semantics.
Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com
"Mark Rae" <ma**@mark-N-O-S-P-A-M-rae.co.uk> wrote in message
news:ev**************@TK2MSFTNGP14.phx.gbl... Hi,
I have a class with several properties, one of which is of the DateTime datatype. However, this property will not always have a value, and I need to check later whether it has a value or not.
When I create a new instance of the class, this property acquires a default value of {1/1/1}, which I don't want at all, as that is a perfectly valid date.
Is there any way to cause a DateTime datatype to have no value at all, which I can check later?
Or is the answer not to use a DataTime datatype and use a generic object datatype instead?
Any assistance gratefully received.
Mark
"Carlos J. Quintero [.NET MVP]" <ca*****@NOSPAMsogecable.com> wrote in
message news:OK**************@tk2msftngp13.phx.gbl... Could you use DateTime.MinValue as a special value to denote no value?
Possibly - thanks for the answer.
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in
message news:uM*************@TK2MSFTNGP15.phx.gbl... In .NET 2.0, you would use the Nullable<T>, with the type parameter T equal to DateTime. This will produce a structure which has a HasValue property which is true if there is a value, false if it is null.
Still using v1.1
If you are using a version of .NET before 2.0, then you could use the SqlDateTime, which supports null semantics.
I'll try that - thanks.
You could also write your own class containing a DateTime that would then be
nullable. This might be easier than having to reference System.Data to use
SqlDateTime.
class MyDateTime
{
public MyDateTime(DateTime dt) { this._dt = dt; }
private DateTime _dt;
public DateTime Value { get { return this._dt; } }
};
"Mark Rae" wrote: "Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard.caspershouse.com> wrote in message news:uM*************@TK2MSFTNGP15.phx.gbl...
In .NET 2.0, you would use the Nullable<T>, with the type parameter T equal to DateTime. This will produce a structure which has a HasValue property which is true if there is a value, false if it is null.
Still using v1.1
If you are using a version of .NET before 2.0, then you could use the SqlDateTime, which supports null semantics.
I'll try that - thanks.
"KH" <KH@discussions.microsoft.com> wrote in message
news:FC**********************************@microsof t.com... You could also write your own class containing a DateTime that would then be nullable. This might be easier than having to reference System.Data to use SqlDateTime.
class MyDateTime { public MyDateTime(DateTime dt) { this._dt = dt; }
private DateTime _dt;
public DateTime Value { get { return this._dt; } } };
Hmm - that looks rather good! Thanks very much :-)
Just for completeness, C# also allows declaring a nullable type like
this:
int? NullableInteger;
The ? denotes a nullable type.
VB does not have a similar syntax.
"Chris Dunaway" <du******@gmail.com> wrote in message
news:11*********************@g44g2000cwa.googlegro ups.com... Just for completeness, C# also allows declaring a nullable type like this:
int? NullableInteger;
The ? denotes a nullable type.
VB does not have a similar syntax.
Interesting - could I apply that here...?
public class CSecurityClassn
{
private DateTime pMaturityDate;
public DateTime MaturityDate
{
get {return pMaturityDate;}
set {pMaturityDate = value;}
}
}
This applies only to VC#.2005
If this were VS.2005 then you wouldn't need a special class. You could
just do this:
DateTime? pNullableDate;
if pNullableDate.HasValue .....
"Chris Dunaway" <du******@gmail.com> wrote in message
news:11**********************@g47g2000cwa.googlegr oups.com... This applies only to VC#.2005
That's what I thought. I've been using 2005 for a while now at home, but
none of my clients is willing to upgrade to a beta product, unsurprisingly! This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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