Difference between the System Array CopyTo and System Array Clone

Question

What   s the difference between the System Array CopyTo   and System Array Clone

User · Answer

Clone   is used to copy only  structure of data array it doesn t copy the actual data   CopyTo   copies the structure as well as actual data

User · Answer

Both perform shallow copies as  PatrickDesjardins said  despite the many misled souls who think that CopyTo does a deep copy    However  CopyTo allows you to copy one array to a specified index in the destination array  giving it significantly more flexibility

User · Answer

The Clone   method returns a new array  a shallow copy  object containing all the elements in the original array   The CopyTo   method copies the elements into another existing array   Both perform a shallow copy   A shallow copy means the contents  each array element  contains references to the same object as the elements in the original array   A deep copy  which neither of these methods performs  would create a new instance of each element s object  resulting in a different  yet identical object   So the difference are    1- CopyTo require to have a destination array when Clone return a new array  2- CopyTo let you specify an index  if required  to the destination array    Edit   Remove the wrong example

User · Answer

object   myarray   new object      one   2   three   4   really big number   2324573984927361       create shallow copy by CopyTo   You have to instantiate your new array first object   myarray2   new object myarray Length     but then you can specify how many members of original array you would like to copy  myarray CopyTo myarray2  0      create shallow copy by Clone object   myarray1    here you don t need to instantiate array     but all elements of the original array will be copied myarray1   myarray Clone   as object       if not sure that we create a shalow copy lets test it myarray 0    0  Console WriteLine myarray 0      print 0 Console WriteLine myarray1 0     print  one  Console WriteLine myarray2 0     print  one    the source

User · Answer

Please note  There is a difference between using String   to StringBuilder     In String - if you change the String  the other arrays we have copied  by CopyTo or Clone  that points to the same string will not change  but the original String array will point to a new String  however  if we use a StringBuilder in an array  the String pointer will not change  therefore  it will affect all the copies we have made for this array  For instance   public void test         StringBuilder   sArrOr   new StringBuilder 1       sArrOr 0    new StringBuilder        sArrOr 0  Append  hello        StringBuilder   sArrClone    StringBuilder   sArrOr Clone        StringBuilder   sArrCopyTo   new StringBuilder 1       sArrOr CopyTo sArrCopyTo 0       sArrOr 0  Append   world         Console WriteLine sArrOr 0          sArrClone 0          sArrCopyTo 0          Outputs  hello world hello world hello world        Same result in int   as using String       int   iArrOr   new int 2       iArrOr 0    0      iArrOr 1    1      int   iArrCopyTo   new int 2       iArrOr CopyTo iArrCopyTo 0       int   iArrClone    int   iArrOr Clone        iArrOr 0         Console WriteLine iArrOr 0          iArrClone 0          iArrCopyTo 0          Output  1 0 0

User · Answer

Both are shallow copies  CopyTo method is not a deep copy  Check the following code    public class TestClass1       public string a    test1      public static void ArrayCopyClone         TestClass1 tc1   new TestClass1        TestClass1 tc2   new TestClass1         TestClass1   arrtest1     tc1  tc2        TestClass1   arrtest2   new TestClass1 arrtest1 Length       TestClass1   arrtest3   new TestClass1 arrtest1 Length        arrtest1 CopyTo arrtest2  0       arrtest3   arrtest1 Clone   as TestClass1         Console WriteLine arrtest1 0  a       Console WriteLine arrtest2 0  a       Console WriteLine arrtest3 0  a        arrtest1 0  a    new        Console WriteLine arrtest1 0  a       Console WriteLine arrtest2 0  a       Console WriteLine arrtest3 0  a         Output is  test1 test1 test1 new new new

User · Answer

The answers are confusing to me  When you say shallow copy  this means that they are still pointing to the same address  Which means  changing either one will change another as well    So if I have A    1 2 3 4  and I clone it and get B    1 2 3 4   Now  if I change B 0    9  This means that A will now be A    9 2 3 4   Is that correct

User · Answer

Both CopyTo   and Clone   make shallow copy  Clone   method makes a clone of the original array  It returns an exact length array   On the other hand  CopyTo   copies the elements from the original array to the destination array starting at the specified destination array index  Note that  this adds elements to an already existing array   The following code will contradict the postings saying that CopyTo   makes a deep copy   public class Test   public string s        Write Main   method and within it call test    private void test     Test   array   new Test 1   array 0    new Test    array 0  s    ORIGINAL    Test   copy   new Test 1   array CopyTo copy  0       Next line displays  ORIGINAL  MessageBox Show  array 0  s       array 0  s   copy 0  s    CHANGED       Next line displays  CHANGED   showing that    changing the copy also changes the original  MessageBox Show  array 0  s       array 0  s       Let me explain it a bit  If the elements of the array are of reference types  then the copy  both for Clone   and CopyTo    will be made upto the first top  level  But the lower level doesn t get copied  If we need copy of lower level also  we have to do it explicitly  That s why after Cloning or Copying of reference type elements  each element in the Cloned or Copied array refers to the same memory location as referred by the corresponding element in the original array  This clearly indicates that no separate instance is created for lower level  And if it were so then changing the value of any element in the Copied or Cloned array would not have effect in the corresponding element of the original array   I think that my explanation is exhaustive but I found no other way to make it understandable

User · Answer

The Clone   method returns a new array  a shallow copy  object containing all the elements in the original array   The CopyTo   method copies the elements into another existing array   Both perform a shallow copy   A shallow copy means the contents  each array element  contains references to the same object as the elements in the original array   A deep copy  which neither of these methods performs  would create a new instance of each element s object  resulting in a different  yet identical object   So the difference are    1- CopyTo require to have a destination array when Clone return a new array  2- CopyTo let you specify an index  if required  to the destination array    Edit   Remove the wrong example

User · Answer

One other difference not mentioned so far is that   with Clone   the destination array need not exist yet since a new one is created from scratch  with CopyTo   not only does the destination array need to already exist  it needs to be large enough to hold all the elements in the source array from the index you specify as the destination

User · Answer

The Clone   method returns a new array  a shallow copy  object containing all the elements in the original array   The CopyTo   method copies the elements into another existing array   Both perform a shallow copy   A shallow copy means the contents  each array element  contains references to the same object as the elements in the original array   A deep copy  which neither of these methods performs  would create a new instance of each element s object  resulting in a different  yet identical object   So the difference are    1- CopyTo require to have a destination array when Clone return a new array  2- CopyTo let you specify an index  if required  to the destination array    Edit   Remove the wrong example

User · Answer

Clone   is used to copy only  structure of data array it doesn t copy the actual data   CopyTo   copies the structure as well as actual data

User · Answer

One other difference not mentioned so far is that   with Clone   the destination array need not exist yet since a new one is created from scratch  with CopyTo   not only does the destination array need to already exist  it needs to be large enough to hold all the elements in the source array from the index you specify as the destination

User · Answer

Array Clone   would perform technically deep copy  when pass the array of int or string to a method as a reference  For example int   numbers   new int     -11  12  -42  0  1  90  68  6  -9      SortByAscending numbers      Sort the array in ascending order by clone the numbers array to local new array  SortByDescending numbers      Same as Ascending order Clone  Even if the methods sort the array of numbers but it wont affect the actual reference passed to the sorting methods i e the number array will be in same unsorted initial format in line no 1  Note  The Clone should be done in the sorting methods

User · Answer

Both CopyTo   and Clone   make shallow copy  Clone   method makes a clone of the original array  It returns an exact length array   On the other hand  CopyTo   copies the elements from the original array to the destination array starting at the specified destination array index  Note that  this adds elements to an already existing array   The following code will contradict the postings saying that CopyTo   makes a deep copy   public class Test   public string s        Write Main   method and within it call test    private void test     Test   array   new Test 1   array 0    new Test    array 0  s    ORIGINAL    Test   copy   new Test 1   array CopyTo copy  0       Next line displays  ORIGINAL  MessageBox Show  array 0  s       array 0  s   copy 0  s    CHANGED       Next line displays  CHANGED   showing that    changing the copy also changes the original  MessageBox Show  array 0  s       array 0  s       Let me explain it a bit  If the elements of the array are of reference types  then the copy  both for Clone   and CopyTo    will be made upto the first top  level  But the lower level doesn t get copied  If we need copy of lower level also  we have to do it explicitly  That s why after Cloning or Copying of reference type elements  each element in the Cloned or Copied array refers to the same memory location as referred by the corresponding element in the original array  This clearly indicates that no separate instance is created for lower level  And if it were so then changing the value of any element in the Copied or Cloned array would not have effect in the corresponding element of the original array   I think that my explanation is exhaustive but I found no other way to make it understandable

User · Answer

Array Clone doesn t require a target destination array to be available when calling the function  whereas Array CopyTo requires a destination array and an index

User · Answer

Please note  There is a difference between using String   to StringBuilder     In String - if you change the String  the other arrays we have copied  by CopyTo or Clone  that points to the same string will not change  but the original String array will point to a new String  however  if we use a StringBuilder in an array  the String pointer will not change  therefore  it will affect all the copies we have made for this array  For instance   public void test         StringBuilder   sArrOr   new StringBuilder 1       sArrOr 0    new StringBuilder        sArrOr 0  Append  hello        StringBuilder   sArrClone    StringBuilder   sArrOr Clone        StringBuilder   sArrCopyTo   new StringBuilder 1       sArrOr CopyTo sArrCopyTo 0       sArrOr 0  Append   world         Console WriteLine sArrOr 0          sArrClone 0          sArrCopyTo 0          Outputs  hello world hello world hello world        Same result in int   as using String       int   iArrOr   new int 2       iArrOr 0    0      iArrOr 1    1      int   iArrCopyTo   new int 2       iArrOr CopyTo iArrCopyTo 0       int   iArrClone    int   iArrOr Clone        iArrOr 0         Console WriteLine iArrOr 0          iArrClone 0          iArrCopyTo 0          Output  1 0 0

User · Answer

Both perform shallow copies as  PatrickDesjardins said  despite the many misled souls who think that CopyTo does a deep copy    However  CopyTo allows you to copy one array to a specified index in the destination array  giving it significantly more flexibility

User · Answer

As stated in many other answers both methods perform shallow copies of the array  However there are differences and recommendations that have not been addressed yet and that are highlighted in the following lists   Characteristics of System Array Clone    Tests  using  NET 4 0  show that it is slower than CopyTo probably because it uses Object MemberwiseClone  Requires casting the result to the appropriate type  The resulting array has the same length as the source    Characteristics of System Array CopyTo    Is faster than Clone when copying to array of same type  It calls into Array Copy inheriting is capabilities  being the most useful ones    Can box value type elements into reference type elements  for example  copying an int   array into an object    Can unbox reference type elements into value type elements  for example  copying a object   array of boxed int into an int    Can perform widening conversions on value types  for example  copying a int   into a long    Can downcast elements  for example  copying a Stream   array into a MemoryStream    if any element in source array is not convertible to MemoryStream an exception is thrown    Allows to copy the source to a target array that has a length greater than the source    Also note  these methods are made available to support ICloneable and ICollection  so if you are dealing with variables of array types you should not use Clone or CopyTo and instead use Array Copy or Array ConstrainedCopy  The constrained copy assures that if the copy operation cannot complete successful then the target array state is not corrupted

User · Answer

Both perform shallow copies as  PatrickDesjardins said  despite the many misled souls who think that CopyTo does a deep copy    However  CopyTo allows you to copy one array to a specified index in the destination array  giving it significantly more flexibility

User · Answer

The Clone   method returns a new array  a shallow copy  object containing all the elements in the original array   The CopyTo   method copies the elements into another existing array   Both perform a shallow copy   A shallow copy means the contents  each array element  contains references to the same object as the elements in the original array   A deep copy  which neither of these methods performs  would create a new instance of each element s object  resulting in a different  yet identical object   So the difference are    1- CopyTo require to have a destination array when Clone return a new array  2- CopyTo let you specify an index  if required  to the destination array    Edit   Remove the wrong example

User · Answer

object   myarray   new object      one   2   three   4   really big number   2324573984927361       create shallow copy by CopyTo   You have to instantiate your new array first object   myarray2   new object myarray Length     but then you can specify how many members of original array you would like to copy  myarray CopyTo myarray2  0      create shallow copy by Clone object   myarray1    here you don t need to instantiate array     but all elements of the original array will be copied myarray1   myarray Clone   as object       if not sure that we create a shalow copy lets test it myarray 0    0  Console WriteLine myarray 0      print 0 Console WriteLine myarray1 0     print  one  Console WriteLine myarray2 0     print  one    the source

User · Answer

Array Clone doesn t require a target destination array to be available when calling the function  whereas Array CopyTo requires a destination array and an index

User · Answer

One other difference not mentioned so far is that   with Clone   the destination array need not exist yet since a new one is created from scratch  with CopyTo   not only does the destination array need to already exist  it needs to be large enough to hold all the elements in the source array from the index you specify as the destination

User · Answer

The answers are confusing to me  When you say shallow copy  this means that they are still pointing to the same address  Which means  changing either one will change another as well    So if I have A    1 2 3 4  and I clone it and get B    1 2 3 4   Now  if I change B 0    9  This means that A will now be A    9 2 3 4   Is that correct

User · Answer

Both perform shallow copies as  PatrickDesjardins said  despite the many misled souls who think that CopyTo does a deep copy    However  CopyTo allows you to copy one array to a specified index in the destination array  giving it significantly more flexibility

User · Answer

One other difference not mentioned so far is that   with Clone   the destination array need not exist yet since a new one is created from scratch  with CopyTo   not only does the destination array need to already exist  it needs to be large enough to hold all the elements in the source array from the index you specify as the destination

User · Answer

Both are shallow copies  CopyTo method is not a deep copy  Check the following code    public class TestClass1       public string a    test1      public static void ArrayCopyClone         TestClass1 tc1   new TestClass1        TestClass1 tc2   new TestClass1         TestClass1   arrtest1     tc1  tc2        TestClass1   arrtest2   new TestClass1 arrtest1 Length       TestClass1   arrtest3   new TestClass1 arrtest1 Length        arrtest1 CopyTo arrtest2  0       arrtest3   arrtest1 Clone   as TestClass1         Console WriteLine arrtest1 0  a       Console WriteLine arrtest2 0  a       Console WriteLine arrtest3 0  a        arrtest1 0  a    new        Console WriteLine arrtest1 0  a       Console WriteLine arrtest2 0  a       Console WriteLine arrtest3 0  a         Output is  test1 test1 test1 new new new

User · Answer

As stated in many other answers both methods perform shallow copies of the array  However there are differences and recommendations that have not been addressed yet and that are highlighted in the following lists   Characteristics of System Array Clone    Tests  using  NET 4 0  show that it is slower than CopyTo probably because it uses Object MemberwiseClone  Requires casting the result to the appropriate type  The resulting array has the same length as the source    Characteristics of System Array CopyTo    Is faster than Clone when copying to array of same type  It calls into Array Copy inheriting is capabilities  being the most useful ones    Can box value type elements into reference type elements  for example  copying an int   array into an object    Can unbox reference type elements into value type elements  for example  copying a object   array of boxed int into an int    Can perform widening conversions on value types  for example  copying a int   into a long    Can downcast elements  for example  copying a Stream   array into a MemoryStream    if any element in source array is not convertible to MemoryStream an exception is thrown    Allows to copy the source to a target array that has a length greater than the source    Also note  these methods are made available to support ICloneable and ICollection  so if you are dealing with variables of array types you should not use Clone or CopyTo and instead use Array Copy or Array ConstrainedCopy  The constrained copy assures that if the copy operation cannot complete successful then the target array state is not corrupted

User · Answer

The Clone   method don t give reference to the target instance just give you a copy  the CopyTo   method copies the elements into an existing instance   Both don t give the reference of the target instance and as many members says they give shallow copy  illusion copy  without reference this is the key

User · Answer

Array Clone   would perform technically deep copy  when pass the array of int or string to a method as a reference  For example int   numbers   new int     -11  12  -42  0  1  90  68  6  -9      SortByAscending numbers      Sort the array in ascending order by clone the numbers array to local new array  SortByDescending numbers      Same as Ascending order Clone  Even if the methods sort the array of numbers but it wont affect the actual reference passed to the sorting methods i e the number array will be in same unsorted initial format in line no 1  Note  The Clone should be done in the sorting methods

User · Answer

The Clone   method don t give reference to the target instance just give you a copy  the CopyTo   method copies the elements into an existing instance   Both don t give the reference of the target instance and as many members says they give shallow copy  illusion copy  without reference this is the key

[c#] Difference between the System.Array.CopyTo() and System.Array.Clone()

Examples related to c#

Examples related to .net

Examples related to arrays

Examples related to .net-2.0