How i can make referance on referance equal null

Question

1.00/5 (2 votes)

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class AAA
  {
      public int X { get; set; }
      public int Y { get; set; }

  }
  class Program
  {
      static void Main(string[] args)
      {
          AAA obj = new AAA();
          Fun( ref obj);
      }
      static void Fun(ref AAA _Obj)
      {
          AAA NewObj=null;
          NewObj = _Obj;
          NewObj = null; //how i can set obj equal null
      }
  }

Posted 8-Apr-13 2:49am

Anderso0on

Updated 8-Apr-13 2:54am

v2

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Comments

CHill60 8-Apr-13 8:58am

You've done it. What is the problem?

Anderso0on 8-Apr-13 9:04am

the object in Main function does not equal null

CHill60 8-Apr-13 9:18am

Instead of NewObj = null; try _Obj = null;

CHill60 8-Apr-13 9:20am

By the way that was not my downvote on the question. @Downvoter - please add a comment as to why you are downvoting the question - it will help the OP to learn

Anderso0on 8-Apr-13 9:26am

class AAA
{
public int X { get; set; }
public int Y { get; set; }

}
class CCC
{
AAA OBJ;
public CCC(ref AAA _obj)
{
OBJ=_obj;
}
void Fun()
{
OBJ = null;
}
}
class Program
{
static void Main(string[] args)
{
AAA obj = new AAA();

CCC obj2=new CCC(ref obj);
}
}

Anderso0on 8-Apr-13 9:27am

if do this how i can obj = null
?????

2 solutions

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CPallini · Answer 1 · 2013-04-08T03:25:00

Solution 1

Quote:
static void Fun(ref AAA _Obj)
{
AAA NewObj=null;
NewObj = _Obj;
NewObj = null; //how i can set obj equal null
}

As already suggested, change the above code to

C#

static void Fun(ref AAA _Obj)
  {
    _Obj = null; 
  }

Posted 8-Apr-13 3:25am

CPallini

Updated 8-Apr-13 3:32am

v2

Comments

Sergey Alexandrovich Kryukov 8-Apr-13 9:32am

Of course. A 5. I answered the same and also tried to explain something about it...
—SA

Sergey Alexandrovich Kryukov 8-Apr-13 9:34am

I think your formatting was not what you wanted to express, so the quote was not separated from your words. I tried to fix it; if you don't mind.
—SA

CPallini 8-Apr-13 10:20am

Thank you for fixing it.

Sergey Alexandrovich Kryukov 8-Apr-13 10:44am

You are very welcome.
—SA

Sergey Alexandrovich Kryukov · Answer 2 · 2013-04-08T03:30:00

You are not even trying to make some object null, you create another reference and make it null. This null reference is itself a stack variable (do you understand how stack works?), so it disappears after the call to Fun is done. You do nothing to the reference AAA, and of course nothing to the object referenced by this reference.

You could make a reference null by this simple method:

C#

static void Nullify(ref object @object) {
    @object = null;
}

It also does not do anything to the referenced object, but it does modify the reference passed be reference.

Maybe this question really can help you to understand things, but don't expect that this exercise can teach you any useful techniques or something. Rather, you need just to draw a picture, how reference types work. When you work with a reference types with some variables or members, such variables and members are separate object, references; but there is also a referenced object, referenced by such variable or member.

When you assign anything, even null, to a variable or a member of a reference type, you never ever modify the referenced object itself; you can only modify it if you use a member of that object.

In practice, passing a reference-type object by reference makes little to now sense; the object itself, even if passed by value, is already referenced. And you don't need to assign null to a reference; however, you can do it just to indicate some condition, to be later checked up using "if" statement.

—SA