CODEWITHSUNDEEP
c#classlogicnullable
juleekwin
juleekwin

Reputation: 531

Class of Nullable objects

This question is more a curiosity then anything...

Say there is a class like:

public class Foo{
public int? x {get; set;}
public int? y {get; set;}
}

And somewhere in the project instances were created:

var foo1= new Foo
         {
           x= 1;
           y= 1;
         };

var foo2= new Foo
         {
           x= 1;
           y= 1;
         };

If for some reason they wanted to check to see if the equal each other and set them to NULL if they are and print to screen...

ex:

if(foo1.x == foo2.x)
   foo1.x = null;
if(foo1.y == foo2.y)
   foo1.y = null;

if(foo1 == null){
   Console.WriteLine("foo1 is NULL");
}else{
   Console.WriteLine("foo1 is not NULL");
}

Which would print?

The instance of foo1 exists, but all it's objects are set to NULL. I'm new to the concept of nullable types so this struck a curiosity in me! (My Visual Studio is on the fritz or I'd test myself)

Upvotes: 1

Views: 89

Answers (4)

user1228
user1228

Reputation:

I have two hands. If my two hands are empty, does that mean I do not exist?

An variable's null state does not depend on any of the properties of the instance it points at.

Upvotes: 5

Neil Mountford
Neil Mountford

Reputation: 2001

foo1 is still an instantiated object and so would not be null so Console.WriteLine("foo1 is not NULL"); would be executed.

If you really needed foo1 == null to return true if x and y are null then you could override the == operator and the Equals() method.

Upvotes: 0

Swift
Swift

Reputation: 1881

You will have the else exucuted foo1 is not NULL, the object itself is not null, but the properties are.

you can set foo1 to null by foo1 = null

Upvotes: 0

IllusiveBrian
IllusiveBrian

Reputation: 3214

As you said, foo itself is still an instantiated object, regardless of the values of its member data, so the else statement would print.

Upvotes: 2

Related Questions