`Array.Copy`

In VB.NET, arrays are initialized to empty memory. But we can copy one array to another with the Array.Copy subroutine.

Copy notes

This function assigns each element in one to each element in another. In this way we effectively initialize arrays.

Example

This program creates 2 five-element arrays. In VB.NET, when we create a five-element array we specify the maximum index of 4. In this program, we assign all 5 elements.

Info Copy() populates the elements of the target array with the elements of the source array. The two arrays are separate in memory.

So If we change the values in the source array at this point, the target array is not affected by that change.

Finally We use a For-Each loop to display each Integer element in the target array, revealing its contents.

Module Module1

    Sub Main()
        ' Source array of 5 elements.
        Dim source(4) As Integer
        source(0) = 1
        source(1) = 2
        source(2) = 3
        source(3) = 4
        source(4) = 5

        ' Create target array and use Array.Copy.
        Dim target(4) As Integer
        Array.Copy(source, target, target.Length)

        ' Display target array.
        For Each element As Integer In target
            Console.WriteLine(element)
        Next
    End Sub

End Module1
2
3
4
5

Several overloads of Array.Copy are available. The simplest overload is shown above—it copies a specified number of elements starting at the first element from one array to another.

And With other overloads, we can specify a sourceIndex and a destinationIndex. This makes it possible to copy a range of elements at an offset.

Tip Using the simplest overload for the required task is ideal. But some programs are simpler overall with the complex overloads.

Summary

Arrays are powerful. With Array.Copy, and related subroutines such as Array.Resize, we manually manipulate arrays—their lengths and their elements.