Pascal-like Set class for VB.net (OK for VB2010 and VB2015)

[gordc1]

Historically, Pascal has been a language that has supported Sets, not available in C and its successors nor in Basic. Sets can be very useful in counting and placing values (of bytes or alphanumeric items) into specific memory. These characteristics are useful in simulating card games, puzzle-solving (as in Sudoko), random number generation without repetition (as in Lotto cards).

The code presented here is in two parts; the SetClass, which contains the methods for Sets and an Application that demonstrates the frequency of letters, numerals and punctuation of a text string.

Sets have a given size capacity; in the SetClass items which have a numerical value in the range of 0 to 127 are allowed. This covers the ASCII family of all common used symbols.

To use the code, open your VB Studio and open a new "Console Application". Give it a name so that you can easily find it later. Select and Copy the top section (the class) and paste immediately below "Module1". The copy and paste the app code immediately below "Sub Main". Save All to compete the installation.

If you find this useful, you may wish to place the SetClass into a Library or into a module of its own.

  ' Author: Gordon Coverley email gcoverley@hotmail.com
    Public Class setClass
        ' version June 30 2018
        'provides methods to use Sets in VB.net
        Private xset() As Byte
        Private Const UPPER = 127

        Public Sub New() 'CONSTRUCTOR
            ReDim Me.xset(UPPER)
            For n As Integer = 0 To UPPER 'clears the set. ex: dim setx as New setclass()
                Me.xset(n) = False
            Next
        End Sub
        Public Shared Operator +(ByVal set1 As setClass, ByVal set2 As setClass) As setClass
            Dim b As Boolean 'union of set1 and set2
            Dim set3 As New setClass()
            For L = 0 To UPPER
                b = set1.xset(L) Or set2.xset(L)
                set3.xset(L) = b
            Next
            Return set3
        End Operator
        Public Shared Operator <>(ByVal set1 As setClass, ByVal set2 As setClass) As Boolean
            'returns TRUE if set1 is different from set2
            Dim result As Boolean = False
            For n As Integer = 0 To UPPER
                If (set1.xset(n) Xor set2.xset(n)) Then
                    result = True
                End If
            Next
            Return result
        End Operator
        Public Shared Operator =(ByVal set1 As setClass, ByVal set2 As setClass) As Boolean
            'returns TRUE if set1 is identical to set2
            Dim result As Boolean = True
            For n As Integer = 0 To UPPER
                If set1.xset(n) <> set2.xset(n) Then
                    result = False
                End If
            Next
            Return result
        End Operator

        Public Shared Operator *(ByVal set1 As setClass, ByVal set2 As setClass) As setClass
            Dim b As Boolean 'intersection of set1 and set2
            Dim set3 As New setClass()
            For L = 0 To UPPER
                b = set1.xset(L) And set2.xset(L)
                set3.xset(L) = b
            Next
            Return set3
        End Operator
        Public Shared Operator -(ByVal set1 As setClass, ByVal set2 As setClass) As setClass
            Dim b As Boolean 'set1 -set2 (items of set2 that are in set1 are removed)
            Dim set3 As New setClass()
            For L = 0 To UPPER
                b = set1.xset(L) And Not (set2.xset(L))
                set3.xset(L) = b
            Next
            Return set3
        End Operator

        Public Sub addItem(ByRef obj As Object) ' adds a char, integer, string to calling set. Does not clear set
            ' ex. myset.additem("abc")
            Dim j As Integer
            If TypeOf obj Is Integer Then
                Me.xset(obj) = True
                Exit Sub
            End If
            If TypeOf obj Is Char Then
                Me.xset(Asc(obj)) = True
                Exit Sub
            End If
            If TypeOf obj Is String Then
                For j = 0 To obj.length - 1
                    Me.xset(Asc(obj(j))) = True
                Next j

                Exit Sub
            End If
        End Sub
        Public Sub removeItem(ByRef obj As Object)  ' removes a char, integer, string in calling set. 
            ' ex. myset.removeitem("abc")
            Dim j As Integer
            If TypeOf obj Is Integer Then
                Me.xset(obj) = False
                Exit Sub
            End If
            If TypeOf obj Is Char Then
                Me.xset(Asc(obj)) = False
                Exit Sub
            End If
            If TypeOf obj Is String Then
                For j = 0 To obj.length - 1
                    Me.xset(Asc(obj(j))) = False
                Next j

                Exit Sub
            End If

        End Sub
        Public Function itemIsIn(ByRef obj As Object) As Boolean
            ' determines if obj is in calling set. When called,parameter MUST be dimensioned as obj.
            Dim j As Integer
            If TypeOf obj Is Integer Then
                If Me.xset(obj) = False Then
                    Return False    ' obj not present
                Else
                    Return True     ' obj is in calling set
                End If
            End If
            If TypeOf obj Is Char Then
                If Me.xset(Asc(obj)) = False Then
                    Return False    ' obj not present
                Else
                    Return True     ' obj is in calling set
                End If
            End If
            If TypeOf obj Is String Then
                Dim q As Boolean = True
                For j = 0 To obj.length - 1
                    If Me.xset(Asc(obj(j))) = False Then
                        q = False    ' obj not present
                        Exit For
                    End If
                Next j
                Return q
            End If
            Return False    'if this is reached, there is an error in item
        End Function
        Public Sub empty() 'clears (empty) the calling set
            Array.Clear(Me.xset, 0, UPPER)
        End Sub
        Public Function contains(ByVal set1 As setClass) As Boolean
            ' returns TRUE if set1 is in calling set, otherwise returns FALSE
            Dim result As Boolean = True
            For L = 0 To UPPER
                If (set1.xset(L)) Then
                    If Not Me.xset(L) Then
                        result = False
                        Exit For
                    End If
                End If
            Next
            Return result
        End Function
        Public Function getCnt() As Byte
            Dim count As Byte 'returns no. of items in set. ex: setx.set_cnt()
            count = 0
            For L = 0 To UPPER
                If Me.xset(L) Then
                    count = count + 1
                End If
            Next
            Return count
        End Function
        Public Function valInSet(ByVal value As Byte) As Boolean 'use ItemIsIn, if you like.
            If Me.xset(value) Then ' tests for value in set. ex: setx.val_in_set(asc("A")
                Return True
            Else
                Return False
            End If
        End Function
        Public Sub addRange(ByVal j As Byte, ByVal k As Byte)
            Dim n As Integer ' fills set with contigous values from j to k inclusive.ex: myset.add_range(48,57)
            For n = j To k ' does not clear the set first.
                Me.xset(n) = True
            Next
        End Sub
        Function toAlpha() As String  'calling set items put into a string, use for display/printing
            Dim s, cs As String
            s = ""
            For k As Integer = 0 To 127  'to convert set to a string
                If Me.xset(k) Then
                    cs = Chr(k)
                    s = s & cs
                End If
            Next
            Return s
        End Function
    End Class
'Application code follows:
 Console.WriteLine("Demo of Set class-Counting vowels,consonants,punctuation, numerals in a string")
        Dim letterset, consonantset, vowelset, punctuationset, numeralset As New setClass
        Dim cntvowels, cntconsonants, cntnumerals, cntpunctuation, other As Integer
        'fill these sets with letters,etc
        letterset.addRange(Asc("A"), Asc("Z"))      'all upper case letters. addRange needs byte parameters
        letterset.addRange(Asc("a"), Asc("z"))      'add lower case letters
        vowelset.addItem("aeiouAEIOU")               ' vowels
        punctuationset.addItem(".,!:;?")             'some punctuation
        numeralset.addItem("0123456789")             'numerals
        consonantset = letterset - vowelset         'subtract vowels from letterset
        'User test message
        Console.Write("Enter a message: ")
        Dim str As String = Console.ReadLine()
        For j As Integer = 0 To str.Length - 1
            Dim b As Object = str(j)
            If consonantset.itemIsIn(b) Then        'note b is an object
                cntconsonants += 1
            ElseIf vowelset.itemIsIn(b) Then
                cntvowels += 1
            ElseIf numeralset.itemIsIn(b) Then
                cntnumerals += 1
            ElseIf punctuationset.itemIsIn(b) Then
                cntpunctuation += 1
            Else
                other += 1
            End If
        Next
        'output counts
        Console.WriteLine("Test string is:- " & str)
        Console.WriteLine("consonants= " & cntconsonants)
        Console.WriteLine("vowels= " & cntvowels)
        Console.WriteLine("numerals= " & cntnumerals)
        Console.WriteLine("punctuation= " & cntpunctuation)
        Console.WriteLine("others= " & other)

        Console.ReadLine()