Topic: Point3d == Null

[shers]

Hi,

How can I check if Point3d == Null?

Point3d InsPt;

If (InsPt == null)
{

}

Thanks

[gile]

Hi,

As I tried to explain you here, Point3d is a value type (as integers, doubles, etc.), and a value type cannot be null.

Please, read almost this thread.

[mohnston]

If you would like to Point3d to be null you can declare it as nullable by adding a question mark (?).

Point3d? InsPt = null;
InsPt = SomeFunctionThatMayOrMayNotSuccessfullyGetAPoint3d(); // Returns a Point3d? NOT a Point3d
If (InsPt != null)
{
    Point3d myPt = InsPt.Value;
}

[huiz]

You can read more information about nullable types here: http://geekswithblogs.net/BlackRabbitCoder/archive/2012/07/12/c.net-little-wondres-the-nullablelttgt-struct.aspx

Weird but in VB.Net a Point3d can be null, but in C# not.

[gile]

Weird but in VB.Net a Point3d can be null, but in C# not.

Not exactly, the VB Nothing keyword isn't an equivalent of null C# keyword, it represents the default value which is effectively null for the reference types, but not for the non nullable value types.

IOW the VB expression:

Code - vb.net: [Select]

1. Dim pt As Point3d = Nothing

is equivalent to the C#

Code - C#: [Select]

1. Point3d pt = new Point3d();

in both cases pt = (0,0,0)

So the VB expression

Code - vb.net: [Select]

1. IsNothing(pt)

will always return False

PS: One more reason I hate VB...

[huiz]

Well thank you for explaining this gile. I didn't know that, I assumed Nothing was something as null.

I'm glad I switched from VB to C# 3 years ago, I don't feel sorry at all