null date?

[evolve]

why doesn't c# seem to support some kind of 'null date'

for instance:

i have an application where the user is not obliged to enter a date until
an event happens (e.g. a bug was fixed on xyz)

the calendar control in asp.net doesn't seem to have a selectedDate = null
property

is there any way around this?
--
#-)

[Madhu [MVP]]

Hi,

The DateTime data type is a value type and not reference
type.

For more information about value types and reference
types, look at these url's

http://msdn.microsoft.com/library/default.asp?
url=/library/en-us/csref/html/vcrefvaluetypes .asp

http://msdn.microsoft.com/library/default.asp?
url=/library/en-us/csref/html/vcrefvaluetypes .asp

The bottom line is, the value type cannot hold null
values unlike reference types.

So the work arounds which i can think of is to,

1) Assign a date like 1/1/1900 which will be considered
as null.
2) Create a class which has a field of type date. This
can be done in a smart way, such that you use it like a
normal value type, i.e., you don't need to use 'new' to
create the instance of the class.
This can be acheived by using implicit operator.
Thus, you get the ease of use of value type and also for
types like date you can assign null value since the class
is a reference type.

Hope this helps!!

Regards,
Madhu

MVP | MCSD.NET

-----Original Message-----
why doesn't c# seem to support some kind of 'null date'

for instance:

i have an application where the user is not obliged to enter a date untilan event happens (e.g. a bug was fixed on xyz)

the calendar control in asp.net doesn't seem to have a selectedDate = nullproperty

is there any way around this?
--
#-)
.

[Mitch Denny]

Hiya,

This is a common challenge for developers with with the split
reference/value type system. Many developers go for a magic date which
"means" null but it is far from ideal. You may like to look at the
NullableTypes project being hosted at SourceForge. It provides wrapper
classes around the standard structs which are nullable. You will probably
want to see what impact these have on performance in your application - the
license terms seem to be OK.

----------------------------------------
- Mitch Denny
- mi*********@mon ash.net
- http://www.monash.net
- [phone]
-

"evolve" <NOngnSPAMpeaSP AMrseNO_S__PAMh otmail.com> wrote in message
news:uX******** ********@TK2MSF TNGP09.phx.gbl. ..

why doesn't c# seem to support some kind of 'null date'

for instance:

i have an application where the user is not obliged to enter a date until
an event happens (e.g. a bug was fixed on xyz)

the calendar control in asp.net doesn't seem to have a selectedDate = null
property

is there any way around this?
--
#-)

[Stu Smith]

You could use System.Data.Sql Types.SqlDate
"evolve" <NOngnSPAMpeaSP AMrseNO_S__PAMh otmail.com> wrote in message
news:uX******** ********@TK2MSF TNGP09.phx.gbl. ..

why doesn't c# seem to support some kind of 'null date'

for instance:

i have an application where the user is not obliged to enter a date until
an event happens (e.g. a bug was fixed on xyz)

the calendar control in asp.net doesn't seem to have a selectedDate = null
property

is there any way around this?
--
#-)

[Brian W]

Use the static property DateTime.MinVal ue. (which is 01/01/0001 12:00AM)

This is considered to be a null date.

HTH
Brian w

"evolve" <NOngnSPAMpeaSP AMrseNO_S__PAMh otmail.com> wrote in message
news:uX******** ********@TK2MSF TNGP09.phx.gbl. ..

why doesn't c# seem to support some kind of 'null date'

for instance:

i have an application where the user is not obliged to enter a date until
an event happens (e.g. a bug was fixed on xyz)

the calendar control in asp.net doesn't seem to have a selectedDate = null
property

is there any way around this?
--
#-)

[Matthew Slyh]

There is one caveat to using DateTime.MinVal ue... the actual date
(01/01/0001) is not supported by most database vendors. For example, I
believe that SQL Server throws an exception for dates less than 1/1/1900.
You can write code to get around this by translating the DateTime.MinVal ue
to a DbNull value before writing it to the database but this is a little
troublesome unless you have a good framework setup. For an enterprise
application, you wouldn't want to rely on individual programmers to
constantly be checking against the DateTime.MinVal ue every time a database
access occurs. As some of the other responses pointed out, a wrapper class
is a good way to avoid some of these issues.

Hopes this helps....

"Brian W" <brianw@gold_de ath_2_spam_rush .com> wrote in message
news:Oe******** *****@TK2MSFTNG P10.phx.gbl...

Use the static property DateTime.MinVal ue. (which is 01/01/0001 12:00AM)

This is considered to be a null date.

HTH
Brian w

"evolve" <NOngnSPAMpeaSP AMrseNO_S__PAMh otmail.com> wrote in message
news:uX******** ********@TK2MSF TNGP09.phx.gbl. ..

why doesn't c# seem to support some kind of 'null date'

for instance:

i have an application where the user is not obliged to enter a date until an event happens (e.g. a bug was fixed on xyz)

the calendar control in asp.net doesn't seem to have a selectedDate = null property

is there any way around this?
--
#-)

[Ed]

Which is great, but they don't serialize...

-----Original Message-----
You could use System.Data.Sql Types.SqlDate
"evolve" <NOngnSPAMpeaSP AMrseNO_S__PAMh otmail.com> wrote in messagenews:uX******* *********@TK2MS FTNGP09.phx.gbl ...

why doesn't c# seem to support some kind of 'null date'

for instance:

i have an application where the user is not obliged to enter a date until an event happens (e.g. a bug was fixed on xyz)

the calendar control in asp.net doesn't seem to have a selectedDate = null property

is there any way around this?
--
#-)

.