VB.NET - List AddRange, InsertRange

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.

Step 1 We create a List and call Add() 4 times. The result is a list with the values 1 through 4 inclusive.

Step 2 We create a new array. In VB.NET, when we create an array we can specify the "last index" of the array as its type.

Step 3 We invoke AddRange, passing the array to the AddRange method, and then display the updated contents of 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.

Part 1 We create a List with 4 elements, and an array with 3 elements. We use a shorter syntax in this example.

List Initialize

Part 2 We insert all the elements from the array at index 1, which is after the first element. We then display the List elements.

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.

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This page was last updated on Dec 8, 2023 (new).

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