Shallow Copy , Deep Copy , Memberwise Copy ,Bitwise copy

Shallow Copy , Deep Copy , Memberwise Copy ,Bitwise copy

• Ty Y

  Shallow copy = Bitwise copy.

  Deep copy = Memberwise copy.

  Long story short, a shallow copy only copies the binary, in memory, print of a class. A deep copy "dives into" the members, and copy their logical data.

  Example: If you've got a class with one member, which is a pointer of irrelevant type, a shallow copy would duplicate the address, leaving you with two classes with pointers to the same value. A deep copy would copy what the pointer addresses, again giving you two classes, but each with a pointer to its own value. Not only will the class be copied, but also whatever types it contains.

  
  
  

• Bobby110uk

  Just to be pedantic the compiler actually doesn't generate code that copies the object one bit at a time - it is at least one byte at a time. But the underlying meaning is the same: the way I think of it is a shallow/bitwise copy can be done using memcpy while a deep/member wise copy requires calling copy constructor/assignment operators for user-defined types. Note: for built in types, like int, char, etc., there is only one way to copy the object and that is a bitwise copy.
  
  

• Sascha Zeidler

  Hi,

  I was confused about these expressions too and looked at your explanations and they were very sensible. But while I was looking at the object browser in visual studio 2005 I saw the following:

  protected object MemberwiseClone()

  Member of System.Object

  Summary:

  Creates a shallow copy of the current System.Object.

  Return Values:

  A shallow copy of the current System.Object.

  This indicates to me that a memberwiseclone is a shallow copy not a deep copy as you have stated above. So I am still confused as to the correct definitions of a memberwise, bitwise, shallow and deep copy. Perhaps the object browser is wrong or perhaps there is some question over these definitions.

  Kind Regards

  Andy

  
  

• zapacila89

  thanks friends for helping me.

  finally i got rid of all confusion

  thanks a lot

  manish

  
  

• Rusty Trawler

  Yes, "byte by byte" is more appropriate. That "bit by bit" thing was just a form of speech like "bitwise copy".

  Regards

  Sahir

  
  

• mark aoki

   

     When you pass an object by value if you haven't made provision for a copy constructor the compiler assumes a bit copy. That means the object is copied bit by bit without considering the (for lack of a better word) "semantics" of the object. Shallow copy and bitwise copy are the same thing.  

  Regards

   Sahir

  
  
• Shallow Copy , Deep Copy , Memberwise Copy ,Bitwise copy