Convert List, array

Lists and arrays are often converted. Both the List and array types in the VB.NET language are useful. But sometimes we require the opposite type.

We can perform conversions with the extension methods ToArray and ToList. This is the shortest and clearest way to perform these conversions.

Example

A List and array of equivalent element type can be converted back and forth. The example uses a List of Integers, but any type could be used.

Module Module1

    Sub Main()
        ' Step 1: create a list and add 3 elements to it.
        Dim list As List(Of Integer) = New List(Of Integer)
        list.Add(1)
        list.Add(2)
        list.Add(3)

        ' Step 2: convert the list to an array.
        Dim array As Integer() = list.ToArray
        Console.WriteLine(array.Length)

        ' Step 3: convert the array to a list.
        Dim list2 As List(Of Integer) = array.ToList

        ' Step 4: display.
        Console.WriteLine(list2.Count)
    End Sub

End Module
3
3

A discussion

The ToArray and ToList extension methods are part of the System.Linq namespace in the .NET Framework. We could also use the List constructor or copy elements in a For-loop.

We invoked the ToArray and ToList extension methods to convert between list and array types. We described the limitations of these methods. They must receive compatible element types.