C# | Copying the Collection<T> elements to an array

Collection<T>.CopyTo(T[], Int32) method is used to copy the entire Collection<T> to a compatible one-dimensional Array, starting at the specified index of the target array. Syntax:

public void CopyTo (T[] array, int index);

Parameters:

array : The one-dimensional Array that is the destination of the elements copied from Collection<T>. The Array must have zero-based indexing. index : The zero-based index in array at which copying begins.

Exceptions:

• ArgumentNullException : If the array is null.
• ArgumentOutOfRangeException : If the index is less than zero.
• ArgumentException : If the number of elements in the source Collection<T> is greater than the available space from index to the end of the destination array.

Below given are some examples to understand the implementation in a better way: Example 1: Output:

A
B
C
D
E

Example 2:

Runtime Error:

Unhandled Exception: System.ArgumentOutOfRangeException: Value has to be >= 0. Parameter name: destinationIndex

Note:

• 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 Collection<T>.
• This method is an O(n) operation, where n is Count.

Reference:

• https://learn.microsoft.com/en-us/dotnet/api/system.collections.objectmodel.collection-1.copyto?view=netframework-4.7.2