How to stop reference of other class object?

Question

I have 2 object of same class as following in c#.

Myclass obj1 = new Myclass();
Myclass obj2 = null;
obj2 = obj1;
obj1.Name = "abc";     //"abc" will also assign to obj2.Name.

When I assign obj1.Name="abc", it will also assign to obj2.Name. I want to stop this. I have tried by const, sealed but I am not getting result. Can anybody suggest me how to stop reference of obj1 on obj2?

You must create a new instance of Myclass of `obj2` to stop referencing from `obj1`. — Joel Legaspi Enriquez, Jul 24 '15 at 06:32
Because `obj1` and `obj2` pointing the same objects. How about _not_ assign their references to each other? — Soner Gönül, Jul 24 '15 at 06:32
[Clone it somehow.](https://msdn.microsoft.com/en-us/library/system.icloneable(v=vs.110).aspx) — Ry-, Jul 24 '15 at 06:33
You have two *variables*. You don't have two *objects*, only **one**. — Lasse V. Karlsen, Jul 24 '15 at 06:34
possible duplicate of [object assignment](http://stackoverflow.com/questions/2486297/object-assignment) — poke, Jul 24 '15 at 06:34
try [MemberwiseClone](https://msdn.microsoft.com/en-us/library/system.object.memberwiseclone(v=vs.100).aspx) - also there are several SO answers on deep copy: [1](http://stackoverflow.com/questions/129389/how-do-you-do-a-deep-copy-an-object-in-net-c-specifically), [2](http://stackoverflow.com/questions/11074381/deep-copy-of-a-c-sharp-object), [3](http://stackoverflow.com/questions/78536/deep-cloning-objects) and this [codeproj article](http://www.codeproject.com/Articles/38270/Deep-copy-of-objects-in-C) — Mark Mikofski, Jul 24 '15 at 06:35

score 4 · Answer 1 · answered Jul 24 '15 at 06:34

You want to deep clone obj1:

Myclass obj1 = new Myclass();
Myclass obj2 = DeepClone(obj1);
obj1.Name = "abc";

One way to deep clone an object is to Serialize it and Deserialize it back.

Here's an example using json.net:

public T DeepClone<T>(T instance)
{
   return JsonConvert.DeserializeObject<T>(JsonConvert.SerializeObject(instance));
}

score 3 · Answer 2 · answered Jul 24 '15 at 06:39

3

You should clone obj1. You can use MemberwiseClone().

Myclass obj2 = (Myclass)obj1.MemberwiseClone();

answered Jul 24 '15 at 06:39

melihorhan

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No, You don't need to remove to answer. Your answer more revealing. – melihorhan Jul 24 '15 at 06:48
I think you should put a disclaimer that this method does a shallow copy, otherwise people might assume otherwise. – Parth Shah Jan 26 '17 at 19:24

Mark Mikofski · Answer 3 · 2015-07-24T06:48:15.370

see my comment above. The msdn docs for MemberwiseClone cover this well.

in MyClass add the following method:

public class MyClass 
{
    ...
    // make a shallow copy
    public MyClass ShallowCopy()
    {
        return (MyClass) this.MemberwiseClone();
    }
}

then you can use ShallowCopy() method to create obj2

Myclass obj1 = new Myclass();
Myclass obj2 = obj1.ShallowCopy();
obj1.Name = "abc";     //"abc" won't assign to obj2.Name.

Asad Saeeduddin · Answer 4 · 2015-07-24T06:46:27.297

The behavior you're seeing is because you simply have two references to a single object. It doesn't matter which reference you use to obtain the object, it's still the same object. I am assuming this is because MyClass is a reference type (i.e. a class).

Since it seems you want value type semantics here, perhaps you want MyClass to be a struct, so that a copy is created on assignment:

struct MyClass
{
    private string _name;
    public MyClass(string name)
    {
        _name = name;
    }

    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }
}

Then your original code works as you wanted:

MyClass joe = new Myclass("Joe");
MyClass bob = joe;
bob.Name = "Bob";

Console.WriteLine(bob.Name); // Bob
Console.WriteLine(joe.Name); // Joe

See it in action here: http://ideone.com/Xwnqsa

score -1 · Answer 5 · answered Jul 24 '15 at 06:35

When you write obj2 = obj1, you are making obj2 point to the object that is obj1 is pointing at. You aren't creating a new separate instance that has the same value as obj1. So in order to prevent any changes that you make to obj1 appear in obj2, you need to make a deep copy of obj1, like the following:

obj2 = new MyClass(obj1);
obj1.Name = "abc";

How to stop reference of other class object?

5 Answers5