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Array.Copy Method (Array, Int64, Array, Int64, Int64)

Copies a range of elements from an Array starting at the specified source index and pastes them to another Array starting at the specified destination index. The length and the indexes are specified as 64-bit integers.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
public static void Copy(
	Array sourceArray,
	long sourceIndex,
	Array destinationArray,
	long destinationIndex,
	long length
)

Parameters

sourceArray
Type: System.Array

The Array that contains the data to copy.

sourceIndex
Type: System.Int64

A 64-bit integer that represents the index in the sourceArray at which copying begins.

destinationArray
Type: System.Array

The Array that receives the data.

destinationIndex
Type: System.Int64

A 64-bit integer that represents the index in the destinationArray at which storing begins.

length
Type: System.Int64

A 64-bit integer that represents the number of elements to copy. The integer must be between zero and Int32.MaxValue, inclusive.

ExceptionCondition
ArgumentNullException

sourceArray is null.

-or-

destinationArray is null.

RankException

sourceArray and destinationArray have different ranks.

ArrayTypeMismatchException

sourceArray and destinationArray are of incompatible types.

InvalidCastException

At least one element in sourceArray cannot be cast to the type of destinationArray.

ArgumentOutOfRangeException

sourceIndex is outside the range of valid indexes for the sourceArray.

-or-

destinationIndex is outside the range of valid indexes for the destinationArray.

-or-

length is less than 0 or greater than Int32.MaxValue.

ArgumentException

length is greater than the number of elements from sourceIndex to the end of sourceArray.

-or-

length is greater than the number of elements from destinationIndex to the end of destinationArray.

The sourceArray and destinationArray parameters must have the same number of dimensions. In addition, destinationArray must already have been dimensioned and must have a sufficient number of elements starting from the destinationIndex position to accommodate the copied data.

When copying between multidimensional arrays, the array behaves like a long one-dimensional array, where the rows (or columns) are conceptually laid end-to-end. For example, if an array has three rows (or columns) with four elements each, copying six elements from the beginning of the array would copy all four elements of the first row (or column) and the first two elements of the second row (or column). To start copying from the second element of the third row (or column), sourceIndex must be the upper bound of the first row (or column) plus the length of the second row (or column) plus two.

If sourceArray and destinationArray overlap, this method behaves as if the original values of sourceArray were preserved in a temporary location before destinationArray is overwritten.

[C++]

This method is equivalent to the standard C/C++ function memmove, not memcpy.

The arrays can be reference-type arrays or value-type arrays. Type downcasting is performed, as required.

  • When copying from a reference-type array to a value-type array, each element is unboxed and then copied. When copying from a value-type array to a reference-type array, each element is boxed and then copied.

  • When copying from a reference-type or value-type array to an Object array, an Object is created to hold each value or reference and then copied. When copying from an Object array to a reference-type or value-type array and the assignment is not possible, an InvalidCastException is thrown.

  • If sourceArray and destinationArray are both reference-type arrays or are both arrays of type Object, a shallow copy is performed. A shallow copy of an Array is a new Array containing references to the same elements as the original Array. The elements themselves or anything referenced by the elements are not copied. In contrast, a deep copy of an Array copies the elements and everything directly or indirectly referenced by the elements.

An ArrayTypeMismatchException is thrown if the arrays are of incompatible types. Type compatibility is defined as follows:

  • A type is compatible with itself.

  • A value type is compatible with Object and with an interface type implemented by that value type. A value type is considered connected to an interface only if it implements that interface directly. Disconnected types are not compatible.

  • Two intrinsic (predefined) value types are compatible if copying from the source type to the destination type is a widening conversion. A widening conversion never loses information, whereas a narrowing conversion can lose information. For example, converting a 32-bit signed integer to a 64-bit signed integer is a widening conversion, and converting a 64-bit signed integer to a 32-bit signed integer is a narrowing conversion. For more information about conversions, see Convert.

  • A nonintrinsic (user-defined) value type is compatible only with itself.

  • Enumerations have an implicit conversion to Enum and to their underlying type.

If every element in sourceArray requires a downcast (for example, from a base class to a derived class or from an interface to an object) and one or more elements cannot be cast to the corresponding type in destinationArray, an InvalidCastException is thrown.

If this method throws an exception while copying, the state of destinationArray is undefined.

This method is an O(n) operation, where n is length.

The following code example shows how to copy from one Array of type Object to another Array of type integer.

using System;
public class SamplesArray  {

   public static void Main()  {

      // Creates and initializes a new Array of type Int32.
      Array myIntArray=Array.CreateInstance( typeof(System.Int32), 5 );
      for ( int i = myIntArray.GetLowerBound(0); i <= myIntArray.GetUpperBound(0); i++ )
         myIntArray.SetValue( i+1, i );

      // Creates and initializes a new Array of type Object.
      Array myObjArray = Array.CreateInstance( typeof(System.Object), 5 );
      for ( int i = myObjArray.GetLowerBound(0); i <= myObjArray.GetUpperBound(0); i++ )
         myObjArray.SetValue( i+26, i );

      // Displays the initial values of both arrays.
      Console.WriteLine( "Int32 array:" );
      PrintValues( myIntArray );
      Console.WriteLine( "Object array:" );
      PrintValues( myObjArray );

      // Copies the first element from the Int32 array to the Object array.
      Array.Copy( myIntArray, myIntArray.GetLowerBound(0), myObjArray, myObjArray.GetLowerBound(0), 1 );

      // Copies the last two elements from the Object array to the Int32 array.
      Array.Copy( myObjArray, myObjArray.GetUpperBound(0) - 1, myIntArray, myIntArray.GetUpperBound(0) - 1, 2 );

      // Displays the values of the modified arrays.
      Console.WriteLine( "Int32 array - Last two elements should now be the same as Object array:" );
      PrintValues( myIntArray );
      Console.WriteLine( "Object array - First element should now be the same as Int32 array:" );
      PrintValues( myObjArray );
   }


   public static void PrintValues( Array myArr )  {
      System.Collections.IEnumerator myEnumerator = myArr.GetEnumerator();
      int i = 0;
      int cols = myArr.GetLength( myArr.Rank - 1 );
      while ( myEnumerator.MoveNext() )  {
         if ( i < cols )  {
            i++;
         } else  {
            Console.WriteLine();
            i = 1;
         }
         Console.Write( "\t{0}", myEnumerator.Current );
      }
      Console.WriteLine();
   }
}
/*
This code produces the following output.

Int32 array:
    1    2    3    4    5
Object array:
    26    27    28    29    30
Int32 array - Last two elements should now be the same as Object array:
    1    2    3    29    30
Object array - First element should now be the same as Int32 array:
    1    27    28    29    30
*/

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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