Today's post is about Arrays and Indexers in VB.NET. Here below you will find a very easy to follow program, that demonstrate arrays and indexer, by implementing some simple tasks that will make you grasp the idea of those 2 features real quick. The main goal of this post, is not really teaching arrays because, come on, you probably already know "all" about them, in fact, it is more to show you how you do that in VB.NET, in this case, compared to all other 22 languages on future posts, which essentially, is the real aim behind this blog.
By the way, if you missed my most recent post, "New Series - Arrays and Indexers", check it out. It has more details about the following program, and a bunch of definitions for the concepts used on this, and the following, posts. Or you can check my previous post about arrays in C# (or the next one in Oxygene) just to compare.
I encourage you to copy the code below and try it yourself, normally, all programs you find in this blog are source code complete, just paste it on your IDE and run it.
Last thing. There is room for improvement of the code, using generics is one example, but Generics, Collections, lambdas, etc. will have their own "series" of posts.
Namespace VbArrays
Module Program
Sub Main()
' Single-dimensional Array(s)
PrintTitle("Reverse Array Elements")
' Declare and Initialize Array of Chars
' You must specify the maximum index instead of the Length.
Dim letters(4) As Char
letters(0) = "A"
letters(1) = "E"
letters(2) = "I"
letters(3) = "O"
letters(4) = "U"
PrintArrayChar(letters)
Dim inverse_letters() As Char = ReverseChar(letters)
PrintArrayChar(inverse_letters)
PrintTitle("Sort Integer Array Elements")
Dim numbers() As Integer = {10, 8, 3, 1, 5}
PrintArrayInt(numbers)
Dim ordered_numbers() As Integer = BubbleSortInt(numbers)
PrintArrayInt(ordered_numbers)
PrintTitle("Sort String Array Elements")
' Declare and Initialize and Array of Strings
Dim names() As String = New String() {
"Damian",
"Rogelio",
"Carlos",
"Luis",
"Daniel"
}
PrintArrayString(names)
Dim ordered_names() As String = BubbleSortString(names)
PrintArrayString(ordered_names)
' Multi-dimensional Array (Matrix row,column)
PrintTitle("Transpose Matrix")
' Matrix row=2,col=3
' A = [6 4 24]
' [1 -9 8]
'
Dim matrix(,) As Integer = New Integer(1, 2) {{6, 4, 24},
{1, -9, 8}}
PrintMatrix(matrix)
Dim transposed_matrix(,) As Integer = TransposeMatrix(matrix)
PrintMatrix(transposed_matrix)
' Jagged Array (Array-of-Arrays)
PrintTitle("Upper Case Random Array & Graph Number of Elements")
'
' Creating an array of string arrays using the String.Split method
' instead of initializing it manually as follows:
'
' Dim text As String()() = New String()() {
' New String() { "word1", "word2", "wordN" },
' New String() { "word1", "word2", "wordM" },
' ...
' }
'
' Text extract from: "El ingenioso hidalgo don Quijote de la Mancha"
'
'
Dim text As String()() = {
"Hoy es el día más hermoso de nuestra vida, querido Sancho;".Split(" "),
"los obstáculos más grandes, nuestras propias indecisiones;".Split(" "),
"nuestro enemigo más fuerte, miedo al poderoso y nosotros mismos;".Split(" "),
"la cosa más fácil, equivocarnos;".Split(" "),
"la más destructiva, la mentira y el egoísmo;".Split(" "),
"la peor derrota, el desaliento;".Split(" "),
"los defectos más peligrosos, la soberbia y el rencor;".Split(" "),
"las sensaciones más gratas, la buena conciencia...".Split(" ")
}
PrintJaggedArray(text)
UpperCaseRandomArray(text)
PrintJaggedArray(text)
GraphJaggedArray(text)
' Array Exceptions
PrintTitle("Common Array Exceptions")
PrintCommonArrayExceptions(Nothing)
PrintCommonArrayExceptions(text)
' Accessing Class Array Elements through Indexer
PrintTitle("Alphabets")
Dim vowels As Alphabet = New Alphabet(4)
vowels(0) = "a"
vowels(1) = "e"
vowels(2) = "i"
vowels(3) = "o"
vowels(4) = "u"
Console.WriteLine(ControlChars.CrLf & "Vowels = {{{0}}}",
String.Join(",", vowels(0), vowels(1), vowels(2), vowels(3), vowels(4)))
Dim en As New Alphabet("abcdefghijklmnopqrstuvwxyz")
Console.WriteLine("English Alphabet = {{{0}}}", en.ToString())
Console.WriteLine("Alphabet Extract en[9..19] = {{{0}}}",
New Alphabet(en.Slice(9, 10)))
Dim word1 As String = String.Join("", en(6), en(14), en(14), en(3))
Dim word2 As String = String.Join("", en(1), en(24), en(4))
Dim word3 As String = String.Join("", en(4), en(21), en(4), en(17),
en(24), en(14), en(13), en(4))
Console.WriteLine(ControlChars.CrLf & "{0} {1}, {2}!" &
ControlChars.CrLf, word1, word2, word3)
End Sub
Function ReverseChar(ByVal arr() As Char) As Char()
Dim reversed(arr.Length - 1) As Char
Dim i As Integer = 0
For j As Integer = arr.Length - 1 To 0 Step -1
reversed(i) = arr(j)
i += 1
Next
Return reversed
End Function
Function BubbleSortInt(ByVal arr() As Integer) As Integer()
Dim swap As Integer = 0
For i As Integer = arr.Length - 1 To 0 Step -1
For j As Integer = 0 To i - 1
If arr(j) > arr(j + 1) Then
swap = arr(j)
arr(j) = arr(j + 1)
arr(j + 1) = swap
End If
Next j
Next i
Return arr
End Function
Function BubbleSortString(ByVal arr() As String) As String()
Dim swap As String = ""
For i As Integer = arr.Length - 1 To 0 Step -1
For j As Integer = 0 To i - 1
If arr(j)(0) > arr(j + 1)(0) Then
swap = arr(j)
arr(j) = arr(j + 1)
arr(j + 1) = swap
End If
Next j
Next i
Return arr
End Function
Function TransposeMatrix(ByVal m(,) As Integer) As Integer(,)
' Transposing a Matrix 2,3
'
' A = [6 4 24]T [ 6 1]
' [1 -9 8] [ 4 -9]
' [24 8]
'
Dim transposed(m.GetUpperBound(1), m.GetUpperBound(0)) As Integer
For i As Integer = 0 To m.GetUpperBound(0)
For j As Integer = 0 To m.GetUpperBound(1)
transposed(j, i) = m(i, j)
Next
Next
Return transposed
End Function
Sub UpperCaseRandomArray(ByRef arr As String()())
Dim r As Random = New Random
Dim i As Integer = r.Next(0, arr.Length - 1)
For j As Integer = 0 To arr(i).Length - 1
arr(i)(j) = arr(i)(j).ToUpper
Next
End Sub
Sub PrintArrayChar(ByVal arr() As Char)
Console.WriteLine(ControlChars.CrLf & "Print Array Content {0}",
arr.GetType().Name.Replace("]", arr.Length.ToString + "]"))
For i As Integer = 0 To arr.Length - 1
Console.WriteLine(" array [{0,2}] = {1,2} ", i, arr(i))
Next
End Sub
Sub PrintArrayInt(ByVal arr() As Integer)
Console.WriteLine(ControlChars.CrLf & "Print Array Content {0}",
arr.GetType.Name.Replace("]", arr.Length.ToString + "]"))
For i As Integer = 0 To arr.Length - 1
Console.WriteLine(" array [{0,2}] = {1,2} ", i, arr(i))
Next
End Sub
Sub PrintArrayString(ByVal arr() As String)
Console.WriteLine(ControlChars.CrLf & "Print Array Content {0}",
arr.GetType.Name.Replace("]", arr.Length.ToString + "]"))
For i As Integer = 0 To arr.Length - 1
Console.WriteLine(" array [{0,2}] = {1,2} ", i, arr(i))
Next
End Sub
Sub PrintMatrix(ByVal m As Integer(,))
Console.WriteLine(ControlChars.CrLf & "Print Matrix Content {0}[{1},{2}]",
m.GetType.Name.Replace("[,]", ""),
(m.GetUpperBound(0) + 1).ToString,
(m.GetUpperBound(1) + 1).ToString)
For i As Integer = 0 To m.GetUpperBound(0)
For j As Integer = 0 To m.GetUpperBound(1)
Console.WriteLine(" array [{0,2},{1,2}] = {2,2} ", i, j, m(i, j))
Next
Next
End Sub
Sub GraphJaggedArray(ByVal arr()() As String)
' When using Arrays, we can use foreach instead of for:
'
' For i As Integer = 0 To arr.Length
' For j As Integer = 0 To arr.Length
'
'
Console.WriteLine(ControlChars.CrLf & "Print Text Content {0}",
arr.GetType.Name)
Dim lineCount As Integer = 1
For Each s In arr
Console.Write("Line{0,2}|", lineCount)
For Each w In s
Console.Write("{0,3}", "*")
Next
Console.WriteLine(" ({0})", s.Length)
lineCount += 1
Next
End Sub
Sub PrintJaggedArray(ByVal arr()() As String)
Dim line As System.Text.StringBuilder
Console.WriteLine(ControlChars.CrLf & "Print Jagged Array Content {0}",
arr.GetType.Name)
For i As Integer = 0 To arr.Length - 1
line = New System.Text.StringBuilder
For j As Integer = 0 To arr(i).Length - 1
line.Append(" " + arr(i)(j))
Next
If line.ToString = line.ToString.ToUpper Then
line.Append(" <-- [UPPERCASED]")
End If
Console.WriteLine(line)
Next
End Sub
Sub PrintCommonArrayExceptions(ByVal arr()() As String)
Try
arr(100)(100) = "hola"
Catch ex As Exception
Console.WriteLine(ControlChars.CrLf & "Exception: " &
ControlChars.CrLf & "{0}" &
ControlChars.CrLf & "{1}", ex.GetType.Name, ex.Message)
End Try
End Sub
Sub PrintTitle(ByVal message As String)
Console.WriteLine()
Console.WriteLine("======================================================")
Console.WriteLine("{0,10}", message)
Console.WriteLine("======================================================")
End Sub
End Module
Class Alphabet
' Array Field
Private letters() As Char
' Indexer Get/Set Property
Default Public Property Item(ByVal index As Integer) As Char
Get
Return letters(index)
End Get
Set(value As Char)
letters(index) = Char.ToUpper(value)
End Set
End Property
' Read-Only Property
Public ReadOnly Property Length() As Integer
Get
Return Me.letters.Length
End Get
End Property
' Constructors
Public Sub New(ByVal size As Integer)
Me.letters = New Char(size) {}
End Sub
Public Sub New(ByVal list As String)
Me.letters = list.ToUpper.ToCharArray
End Sub
Public Sub New(ByVal list() As Char)
Me.letters = list
End Sub
' Overridden Method
Public Overrides Function ToString() As String
Return String.Join(",", letters)
End Function
' Method
Public Function Slice(ByVal start As Integer, ByVal length As Integer) As Char()
Dim result(length) As Char
Dim j As Integer = start
For i As Integer = 0 To length
result(i) = Me(j)
j += 1
Next
Return result
End Function
End Class
End Namespace
The output:
Voilà, that's it. Next post in the following days.
