AddRange, InsertRange. Often in VB.NET programs we need to add just one element at a time to a List. But sometimes, an entire array of elements must be appended or inserted at once.

List

List Add

By using AddRange and InsertRange, we can avoid writing verbose loops to add these elements. Just a single statement is required to add many elements to a List.

AddRange example. This example demonstrates the AddRange method. It creates some collections of data and then calls AddRange to add the array to the List.

Module Module1
    Sub Main()

        ' Step 1: create List.
        Dim list = New List(Of Integer)()
        list.Add(1)
        list.Add(2)
        list.Add(3)
        list.Add(4)

        ' Step 2: new array with maximum index syntax.
        Dim array(2) as Integer
        array(0) = 100
        array(1) = 200
        array(2) = 300

        ' Step 3: call AddRange and display the updated List contents.
        list.AddRange(array)
        For Each value in list
            Console.WriteLine("LIST: {0}", value)
        Next

    End Sub
End Module
LIST: 1
LIST: 2
LIST: 3
LIST: 4
LIST: 100
LIST: 200
LIST: 300

InsertRange example. While AddRange always places elements at the end of the List, InsertRange can insert those elements at any valid index.

List Initialize

Module Module1
    Sub Main()

        ' Part 1: create data collections.
        Dim list = New List(Of Integer)({ 1, 2, 3, 4 })
        Dim array = { 500, 600, 700 }

        ' Part 2: call InsertRange and display the elements afterwards.
        list.InsertRange(1, array)
        For Each value in list
            Console.WriteLine($"ELEMENT: {value}")
        Next

    End Sub
End Module
ELEMENT: 1
ELEMENT: 500
ELEMENT: 600
ELEMENT: 700
ELEMENT: 2
ELEMENT: 3
ELEMENT: 4

In developing VB.NET programs, it is often helpful to reduce excessive lines of code. With AddRange and InsertRange, we can eliminate For-loops in our functions.