CopyTo Method

ReadOnlyCollection<T>.CopyTo Method (T[], Int32)


Copies the entire ReadOnlyCollection<T> to a compatible one-dimensional Array, starting at the specified index of the target array.

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

public void CopyTo(
	T[] array,
	int index


Type: T[]

The one-dimensional Array that is the destination of the elements copied from ReadOnlyCollection<T>. The Array must have zero-based indexing.

Type: System.Int32

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

Exception Condition

array is null.


index is less than zero.


The number of elements in the source ReadOnlyCollection<T> is greater than the available space from index 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 that the enumerator iterates through the ReadOnlyCollection<T>.

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

The following code example demonstrates several members of the ReadOnlyCollection<T> class. The code example creates a List<T> of strings and adds four dinosaur names to it. The code example then wraps the list in a ReadOnlyCollection<T>.

After demonstrating the Count, Contains, Item, and IList.IndexOf members, the code example shows that the ReadOnlyCollection<T> is just a wrapper for the original List<T> by adding a new item to the List<T> and displaying the contents of the ReadOnlyCollection<T>.

Finally, the code example creates an array larger than the collection and uses the CopyTo method to insert the elements of the collection into the middle of the array.

private void synchButton_Click(System.Object sender, System.EventArgs e)
    // If the first displayed item is not the current item.
    if (dataRepeater1.FirstDisplayedItemIndex != dataRepeater1.CurrentItemIndex)
    // Make it the current item.
        dataRepeater1.CurrentItemIndex = dataRepeater1.FirstDisplayedItemIndex;

Universal Windows Platform
Available since 4.5
.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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