Null and DateTime

[tshad]

How do you set DateTime to value of nothing?

I tried:

private DateTime dateCreated = "";

which gets me:

User.cs(24,34): error CS0029: Cannot implicitly convert type 'string' to
'System.DateTime'

I tried:

private DateTime dateCreated = null;

which got me:

User.cs(24,34): error CS0037: Cannot convert null to 'System.DateTime'
because it is a value type

I am doing this in my class where I initially define my local variables.

Thanks,

Tom

 

[Richard Blewett [DevelopMentor]]

How do you set DateTime to value of nothing?

I tried:

private DateTime dateCreated = "";

which gets me:

User.cs(24,34): error CS0029: Cannot implicitly convert type 'string' to
'System.DateTime'

I tried:

private DateTime dateCreated = null;

which got me:

User.cs(24,34): error CS0037: Cannot convert null to 'System.DateTime'
because it is a value type

I am doing this in my class where I initially define my local variables.

Thanks,

Tom

Unfortunately, DateTime is a value type and therefore cannot be set to null
(nothing).

In 1.1 you just have to pick a "Magic Value" which indicates to you it
hasn't been set.

In 2.0, C# supports nullable types so you have

DateTime? dt = null; // note the ?

Regards

Richard Blewett - DevelopMentor
http://www.dotnetconsult.co.uk/weblog
http://www.dotnetconsult.co.uk

 

[Tomislav Tustonic]

How do you set DateTime to value of nothing?

User.cs(24,34): error CS0037: Cannot convert null to 'System.DateTime'
because it is a value type

While waiting for c# 2.0, you can use NullableTypes from
http://nullabletypes.sourceforge.net/
I used it in 2 projects and it works great.

Thanks,

Tom

HTH, Tom

 

[tshad]

"Richard Blewett [DevelopMentor]" <richard at nospam dotnetconsult dot co
dot uk> wrote in message news:[email protected]...

Unfortunately, DateTime is a value type and therefore cannot be set to
null (nothing).

In 1.1 you just have to pick a "Magic Value" which indicates to you it
hasn't been set.

In 2.0, C# supports nullable types so you have

DateTime? dt = null; // note the ?

Can you do this with ints also?

int? iTest = null;

Thanks,

Tom

 

[Jon Skeet [C# MVP]]

Can you do this with ints also?

int? iTest = null;

In 2.0, yes. You can do it for any value type.

 

[tshad]

In 2.0, yes. You can do it for any value type.

And that comes out when?

 

[Jon Skeet [C# MVP]]

And that comes out when?

November 7th is the current date, I believe.

 

[William Stacey [MVP]]

Cool. I totally missed any mention of "?" in the 2.0 stuff so far. Good to
know.

 

[Scott]

Instead of the nullable value types (and until 2.0 comes out), as a
convension I always use DateTime.MinValue


Just something else to consider,
Scott