List<'T>.CopyTo Method (Int32, 'T[], Int32, Int32)


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Copies a range of elements from the List<'T> to a compatible one-dimensional array, starting at the specified index of the target array.

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

member CopyTo : 
        index:int *
        array:'T[] *
        arrayIndex:int *
        count:int -> unit


Type: System.Int32

The zero-based index in the source List<'T> at which copying begins.

Type: 'T[]

The one-dimensional Array that is the destination of the elements copied from List<'T>. The Array must have zero-based indexing.

Type: System.Int32

The zero-based index in array at which copying begins.

Type: System.Int32

The number of elements to copy.

Exception Condition

array is null.


index is less than 0.


arrayIndex is less than 0.


count is less than 0.


index is equal to or greater than the Count of the source List<'T>.


The number of elements from index to the end of the source List<'T> is greater than the available space from arrayIndex to the end of the destination array.

This method uses Array.Copy to copy the elements.

The elements are copied to the Array in the same order in which the enumerator iterates through the List<'T>.

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

The following example demonstrates all three overloads of the CopyTo method. A List<'T> of strings is created and populated with 5 strings. An empty string array of 15 elements is created, and the CopyTo('T[]) method overload is used to copy all the elements of the list to the array beginning at the first element of the array. The CopyTo('T[], Int32) method overload is used to copy all the elements of the list to the array beginning at array index 6 (leaving index 5 empty). Finally, the CopyTo(Int32, 'T[], Int32, Int32) method overload is used to copy 3 elements from the list, beginning with index 2, to the array beginning at array index 12 (leaving index 11 empty). The contents of the array are then displayed.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 8
.NET Framework
Available since 2.0
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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