VB.NET - Array.Resize Examples

Array.Resize. A VB.NET array can be resized. This will either remove elements at the end if you resize it to be smaller, or add elements at the end if you resize it to be bigger.

Array

Resize notes. The Resize method logically allocates a new array, and then copies to it. You can use Array.Resize to develop your own resizable collections.

Array.Copy

Shrink example. To begin, we use Array.Resize on a 4-element integer array. We reduce (shrink) the size to 2 elements. The last 2 elements are erased.

Module Module1 Sub Main() ' Create an array. Dim arr(3) As Integer arr(0) = 10 arr(1) = 20 arr(2) = 30 arr(3) = 40 ' Call Array.Resize to shrink the array. Array.Resize(arr, 2) ' Display. For Each value As Integer In arr Console.WriteLine(value) Next End Sub End Module

10 20

Grow example. This program first declares an array of integers with 3 elements. Then, it displays the elements and also the array's total length.

Next The program invokes the Array.Resize subroutine. This makes the new length of the array 6.

And There are now 3 elements at the end of the example array that were not there before.

For

Module Module1 Sub Main() ' Create array of three elements. Dim arr(2) As Integer arr(0) = 1 arr(1) = 2 arr(2) = 3 ' Display all elements and the length. For Each value As Integer In arr Console.Write(value) Console.Write(" ") Next Console.Write("- ") Console.WriteLine(arr.Length) ' Call Array.Resize. Array.Resize(arr, 6) ' Display all elements and the length. For Each value As Integer In arr Console.Write(value) Console.Write(" ") Next Console.Write("- ") Console.WriteLine(arr.Length) End Sub End Module

1 2 3 - 3 1 2 3 0 0 0 - 6

Zero elements. Why are the elements zero? The default value of an integer on the heap is the value zero. All the bits are set to zeros.

Also For strings the default value will be Nothing, because no objects were allocated for the new references.

Nothing

Summary. Array.Resize() is used in many collections. When a collection such as a List or Dictionary needs to become larger, it calls Array.Resize to resize its internal buffers, which are arrays.

List

Dictionary

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This page was last updated on Aug 27, 2021 (image).

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