Array.Copy Method (Array, Array, Int32)


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Copies a range of elements from an Array starting at the first element and pastes them into another Array starting at the first element. The length is specified as a 32-bit integer.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

public static void Copy(
	Array sourceArray,
	Array destinationArray,
	int length


Type: System.Array

The Array that contains the data to copy.

Type: System.Array

The Array that receives the data.

Type: System.Int32

A 32-bit integer that represents the number of elements to copy.

Exception Condition

sourceArray is null.


destinationArray is null.


sourceArray and destinationArray have different ranks.


sourceArray and destinationArray are of incompatible types.


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


length is less than zero.


length is greater than the number of elements in sourceArray.


length is greater than the number of elements in 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 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).

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.


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.

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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