VB.Net Tutorial/Collections/Array Sort Reverse

Array.BinarySearch

<source lang="vbnet">Imports System.Collections Public Class Tester

  Shared Sub Main()
     Dim integerValues As Integer() = {1, 2, 3, 4, 5, 6}
     Dim integerElement As Integer
     For Each integerElement In integerValues
        Console.WriteLine(integerElement)
     Next
     Dim result As Integer = Array.BinarySearch(integerValues, 5)
     If result >= 0 Then
        Console.WriteLine("5 found at element " & result &" in integerValues")
     Else
        Console.WriteLine("5 not found" & " in integerValues")
     End If
  End Sub

End Class</source>

1
2
3
4
5
6
5 found at element 4 in integerValues

Array Reverse and Sort

<source lang="vbnet">Option Strict On

Imports System
Class Tester
    Public Shared Sub DisplayArray(ByVal theArray( ) As Object)
        Dim obj As Object
        For Each obj In theArray
            Console.WriteLine("Value: {0}", obj)
        Next obj
        Console.WriteLine(ControlChars.Lf)
    End Sub 
    Public Shared Sub Main( )
        Dim myArray As [String]( ) = {"W", "s", "J", "t"}
        Console.WriteLine("Display myArray...")
        DisplayArray(myArray)
        Console.WriteLine("Reverse and display myArray...")
        Array.Reverse(myArray)
        DisplayArray(myArray)
        Dim myOtherArray As [String]( ) ={"W", "d", "e", "s", "o", "e", "f", "t"}
        Console.WriteLine("Display myOtherArray...")
        DisplayArray(myOtherArray)
        Console.WriteLine("Sort and display myOtherArray...")
        Array.Sort(myOtherArray)
        DisplayArray(myOtherArray)
    End Sub "Main
End Class "Tester</source>

Display myArray...
Value: W
Value: s
Value: J
Value: t

Reverse and display myArray...
Value: t
Value: J
Value: s
Value: W

Display myOtherArray...
Value: W
Value: d
Value: e
Value: s
Value: o
Value: e
Value: f
Value: t

Sort and display myOtherArray...
Value: d
Value: e
Value: e
Value: f
Value: o
Value: s
Value: t
Value: W

Array.Sort and Array.IndexOf

<source lang="vbnet">Imports System.Collections

public class Test

  public Shared Sub Main
       Dim StringArray() As String = {"This", "is", "a", "test"}
       Dim E As IEnumerator = StringArray.GetEnumerator()
   
       While (E.MoveNext())
         Console.WriteLine(E.Current())
       End While
   
       Dim NewArray(StringArray.Length) As String
       Array.Copy(StringArray, NewArray, StringArray.Length)
   
       Console.WriteLine(Array.IndexOf(NewArray, "a"))
  End Sub

End class</source>

This
is
a
test
2

Demonstrating binary search of an array

<source lang="vbnet">Public Class Tester

   Dim Shared array1 As Integer() = New Integer(14) {}
   Public Shared Sub Main
     Dim i As Integer
     For i = 0 To array1.GetUpperBound(0)
        array1(i) = 2 * i
     Next
     Dim searchKey As Integer = 8
     Dim element As Integer = BinarySearch(array1, searchKey)
     If element <> -1 Then
        Console.WriteLine("Found value in element " & element)
     Else
        Console.WriteLine("Value not found")
     End If

   End Sub
  " performs binary search
  Shared Function BinarySearch(ByVal array As Integer(), _
     ByVal key As Integer) As Integer
     Dim low As Integer = 0                 " low index
     Dim high As Integer = array.GetUpperBound(0) " high index 
     Dim middle As Integer             " middle index
     While low <= high
        middle = (low + high) \ 2
        If key = array(middle) Then     " match
           Return middle
        ElseIf key < array(middle) Then " search low end
           high = middle - 1            " of array
        Else
           low = middle + 1
        End If
     End While
     Return -1 " search key not found
  End Function " BinarySearch

End Class</source>

Found value in element 4

Linear search of an array

<source lang="vbnet">Public Class Tester

   Public Shared Sub Main
   
     Dim array1 As Integer() = New Integer(19) {}
     Dim randomNumber As Random = New Random()
     Dim i As Integer
     " creates string containing 11 random numbers
     For i = 0 To array1.GetUpperBound(0)
        array1(i) = randomNumber.Next(1000)
        Console.Write ( array1(i) & " ")
     Next
     Console.WriteLine("")

     Dim searchKey As Integer = 12
     Dim element As Integer = LinearSearch(searchKey, array1)
     If element <> -1 Then
        Console.WriteLine("Found Value in index " & element)
     Else
        Console.WriteLine("Value Not Found")
     End If
   End Sub
   Shared Function LinearSearch(ByVal key As Integer, _
     ByVal numbers As Integer()) As Integer
     Dim n As Integer
     " structure iterates linearly through array
     For n = 0 To numbers.GetUpperBound(0)
        If numbers(n) = key Then
           Return n
        End If
     Next
     Return -1
  End Function " LinearSearch

End Class</source>

269 875 968 591 930 801 98 760 596 715 433 655 902 602 257 186 470 856 277 109
Value Not Found

Reverse the contents of an array

<source lang="vbnet">Public Class Tester

   Public Shared Sub Main
   
       Dim arrayReverse() As String = {"A", "B", "C", "D", "E"}
       For Each fruit As String In arrayReverse
           Console.WriteLine(fruit)
       Next fruit
       Array.Reverse(arrayReverse)
       For Each fruit As String In arrayReverse
           Console.WriteLine(fruit)
       Next fruit
   End Sub

End Class</source>

A
B
C
D
E
E
D
C
B
A