Praxisprojekte

Module Program
    Function Sieb(n As Integer) As List(Of Integer)
        Dim prim(n) As Boolean
        For i As Integer = 2 To n
            prim(i) = True
        Next
        For i As Integer = 2 To CInt(Math.Sqrt(n))
            If prim(i) Then
                For j As Integer = i * i To n Step i
                    prim(j) = False
                Next
            End If
        Next
        Dim erg As New List(Of Integer)
        For i As Integer = 2 To n
            If prim(i) Then erg.Add(i)
        Next
        Return erg
    End Function

    Sub Main()
        Console.WriteLine(String.Join(" ", Sieb(50)))
        Console.WriteLine(Sieb(10000).Count)
    End Sub
End Module

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47
1229

Module Program
    Function Verschiebe(text As String, schluessel As Integer) As String
        Dim erg As New System.Text.StringBuilder()
        For Each c In text
            If Char.IsLower(c) Then
                erg.Append(ChrW((AscW(c) - AscW("a"c) + schluessel + 26) Mod 26 + AscW("a"c)))
            ElseIf Char.IsUpper(c) Then
                erg.Append(ChrW((AscW(c) - AscW("A"c) + schluessel + 26) Mod 26 + AscW("A"c)))
            Else
                erg.Append(c)
            End If
        Next
        Return erg.ToString()
    End Function

    Function IstPalindrom(s As String) As Boolean
        Dim t = New String(s.ToLower().Where(Function(c) Char.IsLetter(c)).ToArray())
        Return t = StrReverse(t)
    End Function

    Sub Main()
        Dim geheim = Verschiebe("Hallo VB!", 3)
        Console.WriteLine(geheim)
        Console.WriteLine(Verschiebe(geheim, -3))
        Console.WriteLine(IstPalindrom("Anna") & " " & IstPalindrom("Basic") & " " & IstPalindrom("Ein Esel lese nie"))
    End Sub
End Module

Kdoor YE!
Hallo VB!
True False True

Module Program
    Class Verkauf
        Public Property Region As String
        Public Property Produkt As String
        Public Property Menge As Integer
        Public Property Preis As Decimal
        Public ReadOnly Property Umsatz As Decimal
            Get
                Return Menge * Preis
            End Get
        End Property
    End Class

    Sub Main()
        Dim daten As New List(Of Verkauf) From {
            New Verkauf With {.Region = "Nord", .Produkt = "Apfel", .Menge = 10, .Preis = 1.2D},
            New Verkauf With {.Region = "Sued", .Produkt = "Birne", .Menge = 5, .Preis = 0.8D},
            New Verkauf With {.Region = "Nord", .Produkt = "Birne", .Menge = 8, .Preis = 0.8D},
            New Verkauf With {.Region = "West", .Produkt = "Apfel", .Menge = 20, .Preis = 1.1D},
            New Verkauf With {.Region = "Sued", .Produkt = "Apfel", .Menge = 7, .Preis = 1.2D}
        }
        For Each g In daten.GroupBy(Function(v) v.Region).OrderBy(Function(x) x.Key)
            Console.WriteLine($"{g.Key,-5} {g.Sum(Function(v) v.Umsatz),7:F2}")
        Next
        Console.WriteLine($"Gesamt: {daten.Sum(Function(v) v.Umsatz):F2}")
        Dim bester = daten.OrderByDescending(Function(v) v.Umsatz).First()
        Console.WriteLine($"Bester Posten: {bester.Produkt} in {bester.Region}")
        Console.WriteLine($"Äpfel: {daten.Where(Function(v) v.Produkt = "Apfel").Sum(Function(v) v.Menge)}")
    End Sub
End Module

Nord    18.40
Sued    12.40
West    22.00
Gesamt: 52.80
Bester Posten: Apfel in West
Äpfel: 37

Module Program
    Private bestanden As Integer = 0
    Private fehler As Integer = 0

    Sub Pruefe(name As String, bedingung As Boolean)
        If bedingung Then
            bestanden += 1
            Console.WriteLine("ok     " & name)
        Else
            fehler += 1
            Console.WriteLine("FEHLER " & name)
        End If
    End Sub

    Function Fak(n As Integer) As Integer
        If n <= 1 Then Return 1
        Return n * Fak(n - 1)
    End Function

    Sub Main()
        Pruefe("Fak(5)", Fak(5) = 120)
        Pruefe("Fak(0)", Fak(0) = 1)
        Pruefe("Reverse", StrReverse("abc") = "cba")
        Pruefe("absichtlich falsch", 1 + 1 = 3)
        Console.WriteLine($"{bestanden} bestanden, {fehler} fehlgeschlagen")
    End Sub
End Module

ok     Fak(5)
ok     Fak(0)
ok     Reverse
FEHLER absichtlich falsch
3 bestanden, 1 fehlgeschlagen