Task: Holidays related to Easter



C#: using System;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;

internal class Program
{
    private static readonly OrderedDictionary _holidayOffsets = new OrderedDictionary
                                                                    {
                                                                        {"Easter", 0},
                                                                        {"Ascension", 39},
                                                                        {"Pentecost", 49},
                                                                        {"Trinity", 56},
                                                                        {"Corpus", 60},
                                                                    };

    static void Main(string[] args)
    {
        Console.WriteLine("Christian holidays, related to Easter, for each centennial from 400 to 2100 CE:");
        for (int year = 400; year <= 2100; year += 100)
            OutputHolidays(year);

        Console.WriteLine();
        Console.WriteLine("Christian holidays, related to Easter, for years from 2010 to 2020 CE:");
        for (int year = 2010; year <= 2020; year += 1)
            OutputHolidays(year);
    }

    static void OutputHolidays(int year)
    {
        var easter = CalculateEaster(year);
        var holidays = from kp in _holidayOffsets.OfType<DictionaryEntry>()
                       let holiday = easter.AddDays(Convert.ToInt32(kp.Value))
                       select kp.Key + ": " + string.Format("{0,2:ddd} {0,2:%d} {0:MMM}", holiday);
        Console.WriteLine("{0,4} {1}", year, string.Join(", ", holidays.ToArray()));
    }

    static DateTime CalculateEaster(int year)
    {
        var a = year % 19;
        var b = year / 100;
        var c = year %100;
        var d = b / 4;
        var e = b % 4;
        var f = (b + 8) / 25;
        var g = (b - f + 1) / 3;
        var h = (19 * a + b - d - g + 15) % 30;
        var i = c / 4;
        var k = c % 4;
        var l = (32 + 2 * e + 2 * i - h - k) % 7;
        var m = (a + 11 * h + 22 * l) / 451;
        var numerator = h + l - 7 * m + 114;
        var month = numerator / 31;
        var day = (numerator % 31) + 1;
        return new DateTime(year, month, day);
    }
}






VB: Public dates As Variant
Private Function easter(year_ As Integer) As Date

    Dim a As Integer, b As Integer, c As Integer, d As Integer, e As Integer
    Dim f As Integer, g As Integer, h As Integer, i As Integer, k As Integer
    Dim l As Integer, m As Integer, n As Integer
    a = year_ Mod 19
    b = year_ \ 100
    c = year_ Mod 100
    d = b \ 4
    e = b Mod 4
    f = (b + 8) \ 25
    g = (b - f + 1) \ 3
    h = (19 * a + b - d - g + 15) Mod 30
    i = c \ 4
    k = c Mod 4
    l = (32 + 2 * e + 2 * i - h - k) Mod 7
    m = (a + 11 * h + 22 * l) \ 451
    n = h + l - 7 * m + 114
    month_ = n \ 31
    day_ = n Mod 31 + 1
    easter = DateSerial(year_, month_, day_)
End Function
 
Private Sub show(year_ As Integer)
    If year_ = 0 Then
        Debug.Print , "Easter", "Ascension", "Pentecost", "Trinity", "Corpus"
    Else
        Dim e As Date
        e = easter(year_)
        Debug.Print Format(year_, "@@@@"),
        For i = 1 To UBound(dates)
            Debug.Print Format(e + dates(i, 2), "ddd dd mmm"),
        Next i
        Debug.Print
    End If
End Sub

Public Sub main()
    Dim year_ As Integer
    dates = [{"Easter   ",0; "Ascension",39; "Pentecost",49; "Trinity  ",56; "Corpus   ",60}]
    show 0
    For year_ = 400 To 2000 Step 100
        show year_
    Next year_
    Debug.Print
    show 0
    For year_ = 2010 To 2020
        show year_
    Next year_
End Sub