Deep copy and shallow copy

Question

Would like to know what is deep copy and shallow copy in C#.NET in a simple way with practical understanding.

Niradhip Chakraborty · Answer

There is only one way to do a deep copy in C#.NET and that is to reinstantiate another tree of objects and copy the values across , in C++ it would be copy constructor There is ONE MAJOR exception to this, and that is you can make a deep copy very easily by using the "BinaryFormatter and the MemoryStream object" here is some sample but not tested, you can test it. public class MyClass : ICloneable { public MyClass ICloneable.Clone() // implement method { MemoryStream ms = new MemoryStream(); // create MemoryStream BinaryFormatter bf = new BinaryFormatter(null, new StreamingContext(StreamingContextStates.Clone)) bf.Serialize(ms, this) ms.Seek(0, SeekOrigin.Begin) MyClass obj; obj = DirectCast(bf.Deserialize(ms), MyClass); ms.Close(); return obj; } } don't delete or dispose the obj; and if you have references to the instance of the object then you can not explicitly dispose or destruct it anyways. now you can't kill the managed class directly but you can assign the null reference. Refers to a method of cloning—copying—an object in which the clone may be associated to data shared by both the original and the copy. Thus, the original and the clone will both reference the same instances of any objects referenced by the original. In other words, a shallow copy contains copies only of instance variables but not of any objects pointed to by reference variables. Check out the folllowing URLs,you will have a more prominent view. 1.http://www.c-sharpcorner.com/Forums/ShowMessages.aspx?ThreadID=40403 2.http://www.codeproject.com/KB/cs/ShallowVsDeepCopy.aspx

Puran Mehra · Answer

Like to know examples where shallow copy and deepcopy is used in C#.NET context. Want explanation at beginner level.

Niradhip Chakraborty · Answer

class MyBaseClass { public static string CompanyName = "My Company"; public int age; public string name; } class MyDerivedClass : MyBaseClass { static void Main() { // Creates an instance of MyDerivedClass and assign values to its fields. MyDerivedClass m1 = new MyDerivedClass(); m1.age = 42; m1.name = "Sam"; // Performs a shallow copy of m1 and assign it to m2. MyDerivedClass m2 = (MyDerivedClass)m1.MemberwiseClone(); Console.ReadKey(); } } simply saying, shallow copy copies the structure of the object, deep copy copies structure as well as data. The MemberwiseClone method creates a shallow copy by creating a new object, and then copying the nonstatic fields of the current object to the new object. If a field is a value type, a bit-by-bit copy of the field is performed. If a field is a reference type, the reference is copied but the referred object is not; therefore, the original object and its clone refer to the same object. in short: The easiest way to think of it is a shallow copy allows you to replicate the array once... it then ignores the relationship it has with the original array. The deep copy will be persistent and any changes you make to the original array will be reflected in both copies. 1:OriginalArray = DeepArray; 2:OriginalArray = ShallowArray.Clone();

Deep copy and shallow copy

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