Creating a copy of an object in C

Question

Please have a look at the code below  excerpt from a C  book   public class MyClass        public int val    public struct myStruct        public int val    public class Program        private static void Main string   args                 MyClass objectA   new MyClass            MyClass objectB   objectA           objectA val   10          objectB val   20           myStruct structA   new myStruct            myStruct structB   structA           structA val   30          structB val   40           Console WriteLine  quot objectA val    0  quot   objectA val           Console WriteLine  quot objectB val    0  quot   objectB val           Console WriteLine  quot structA val    0  quot   structA val           Console WriteLine  quot structB val    0  quot   structB val            Console ReadKey             I understands it produces the output below  objectA val   20 objectB val   20 structA val   30 structB val   40  The last two lines of the output I have no problem with  but the first two tell me that objectA and objectB are pointing to the same memory block  since in C   objects are reference types   The question is how do make objectB  a copy of objectA so that it points to a different area in memory  I understand that trying to assign their members may not work since those members may be references  too  So how do I go about making objectB a completely different entity from objectA

User · Accepted Answer

There is no built-in way  You can have MyClass implement the IClonable interface  but it is sort of deprecated  or just write your own Copy Clone method  In either case you will have to write some code    For big objects you could consider Serialization   Deserialization  through a MemoryStream   just to reuse existing code    Whatever the method  think carefully about what  a copy  means exactly  How deep should it go  are there Id fields to be excepted etc

User · Answer

You could do   class myClass   ICloneable       public String test      public object Clone                 return this MemberwiseClone              then you can do  myClass a   new myClass    myClass b    myClass a Clone      N B  MemberwiseClone   Creates a shallow copy of the current System Object

User · Answer

The easiest way to do this is writing a copy constructor in the MyClass class   Something like this   namespace Example       class MyClass               public int val           public MyClass                                public MyClass MyClass other                        val   other val                      The second constructor simply accepts a parameter of his own type  the one you want to copy  and creates a new object assigned with the same value  class Program       static void Main string   args                MyClass objectA   new MyClass            MyClass objectB   new MyClass objectA           objectA val   10          objectB val   20          Console WriteLine  objectA val    0    objectA val           Console WriteLine  objectB val    0    objectB val           Console ReadKey              output   objectA val   10  objectB val   20

User · Answer

There s already a question about this  you could perhaps read it  Deep cloning objects  There s no Clone   method as it exists in Java for example  but you could include a copy constructor in your clases  that s another good approach   class A     private int attr    public int Attr          get   return attr         set   attr   value          public A              public A A p           this attr   p Attr            This would be an example  copying the member  Attr  when building the new object

[c#] Creating a copy of an object in C#

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