C# | Copying the Collection<T> elements to an array
Last Updated :
01 Feb, 2019
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:
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
class GFG {
public static void Main()
{
Collection< string > myColl = new Collection< string >();
myColl.Add( "A" );
myColl.Add( "B" );
myColl.Add( "C" );
myColl.Add( "D" );
myColl.Add( "E" );
string [] myArr = new string [myColl.Count];
myColl.CopyTo(myArr, 0);
foreach ( string str in myArr)
{
Console.WriteLine(str);
}
}
}
|
Output:
A
B
C
D
E
Example 2:
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
class GFG {
public static void Main()
{
Collection< int > myColl = new Collection< int >();
myColl.Add(2);
myColl.Add(3);
myColl.Add(4);
myColl.Add(5);
int [] myArr = new int [myColl.Count];
myColl.CopyTo(myArr, -5);
foreach ( int i in myArr)
{
Console.WriteLine(i);
}
}
}
|
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:
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