Arrays

An array is a variable (space in memory), which is split into chunks, and accessed by means of an index or subscript.

How to sort an array

You can sort an array either in ascending or descending order.

NOTE: The sort will be based on the first character of each line in the array.

How to sort an array - simple bubble sort

This procedure executes a Bubble Sort on an array of numbers:

Public Class Form1

Dim NumberInList As Integer

Dim Swapped As Boolean = False

Dim List(8) As Integer

Dim Dummy As Integer

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

'set up the array

List(0) = 44

List(1) = 22

List(2) = 15

List(3) = 17

List(4) = 3

List(5) = 41

List(6) = 32

List(7) = 9

'show list in listbox

For count = 0 To 7

lstNumbers.Items.Add(List(count))

Private Sub cmdStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdStart.Click

'carry out bubble sort on list of numbers

NumberInList = 8

For Pass = 1 To NumberInList

Swapped = False

For count = 1 To NumberInList

If List(count) < List(count - 1) Then

Dummy = List(count)

List(count) = List(count - 1)

List(count - 1) = Dummy

Swapped = True

lstNumbers.Items.Clear()

For count2 = 0 To 8

lstNumbers.Items.Add(List(count2))

End Sub

End Class

Bubble Sort a textfile using a sorted array

This procedure aims to sort a textfile into descending order, then find the top 5 performers.

The textfile is read into an array and the array is sorted, before writing the contents of the array back to the textfile.

Textfile BEFORE bubble sort:

Textfile AFTER bubble sort:

'The code sorts a textfile in ascending order, depending on a value in a certain position in the text file. In this instance, I sorted on a score in positions 31/32. The FIND button above, sorts the file, then outputs the top 5 performers.

Public Class Form1

Private Sub btnFindTop5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFindTop5.Click

'Firstly, the array needs to be sorted into descending score order

'Using a bubble sort:

'reads the player stats text file

Dim MyTop5PerformersFile() As String = File.ReadAllLines("playerstats.txt")

Dim TempSort As String

Dim Filelength As Integer = MyTop5PerformersFile.Length

For count = 1 To UBound(MyTop5PerformersFile)

For position = UBound(MyTop5PerformersFile) To 1 Step -1

'Note, this code will only work if numbers 1-9 are stored as " 1", " 2", etc (i.e. with a space before any single digits.

If Mid(MyTop5PerformersFile(position), 31, 2) < Mid(MyTop5PerformersFile(position - 1), 31, 2) Then

TempSort = MyTop5PerformersFile(position - 1)

MyTop5PerformersFile(position - 1) = MyTop5PerformersFile(position)

MyTop5PerformersFile(position) = TempSort

End If

File.WriteAllLines("playerstats.txt", MyTop5PerformersFile)

'To get top 5 performances:

For recordnumber = 0 To 4

If recordnumber = 0 Then

lblFirstName1.Text = Mid(MyTop5PerformersFile(recordnumber), 11, 10)

lblSurname1.Text = Mid(MyTop5PerformersFile(recordnumber), 21, 10)

lblLastScore1.Text = Mid(MyTop5PerformersFile(recordnumber), 31, 2)

End If

If recordnumber = 1 Then

lblFirstName2.Text = Mid(MyTop5PerformersFile(recordnumber), 11, 10)

lblSurname2.Text = Mid(MyTop5PerformersFile(recordnumber), 21, 10)

lblLastScore2.Text = Mid(MyTop5PerformersFile(recordnumber), 31, 2)

End If

If recordnumber = 2 Then

lblFirstName3.Text = Mid(MyTop5PerformersFile(recordnumber), 11, 10)

lblSurname3.Text = Mid(MyTop5PerformersFile(recordnumber), 21, 10)

lblLastScore3.Text = Mid(MyTop5PerformersFile(recordnumber), 31, 2)

End If

If recordnumber = 3 Then

lblFirstName4.Text = Mid(MyTop5PerformersFile(recordnumber), 11, 10)

lblSurname4.Text = Mid(MyTop5PerformersFile(recordnumber), 21, 10)

lblLastScore4.Text = Mid(MyTop5PerformersFile(recordnumber), 31, 2)

End If

If recordnumber = 4 Then

lblFirstName5.Text = Mid(MyTop5PerformersFile(recordnumber), 11, 10)

lblSurname5.Text = Mid(MyTop5PerformersFile(recordnumber), 21, 10)

lblLastScore5.Text = Mid(MyTop5PerformersFile(recordnumber), 31, 2)

End If

End Class