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.

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.

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.