'Weekday and Leap Year Calculator by SierraKen

'October 14, 2024



'This app tells you what weekday of the year a date falls on or if you want to see if a certain year has a Leap Year.

'It can use anywhere from 1753 A.D. to 9999 A.D because 1753 is when the Gregorian Calendar started.

'Most of this code is taken from my Calendar Maker on the QB64 Phoenix forum.

'Thank you to the guys on forum for the help!



Dim leap As Single

Dim dd As Single

Dim olddd As Single

Dim mm As Single

Dim oldmm As Single

Dim yy As Single

Dim oldyy As Single

Dim days As Single

Dim weekday As Single



_Title "Weekday and Leap Year Calculator by SierraKen"

start:

leap = 0: dd = 0: mm = 0: yy = 0: days = 0: weekday = 0: oldyy = 0: menu = 0

ag$ = ""

Cls

Print: Print

Print "                Weekday and Leap Year Calculator by SierraKen"

Print: Print: Print

Print "(1) Calculate Weekday"

Print "(2) Calculate Leap Year"

Print "(3) Quit"

Print: Print

Print "Press 1, 2, or 3."

themenu:

menu$ = InKey$

If menu$ = "1" Then GoTo month:

If menu$ = "2" Then GoTo leapyear:

If menu$ = "3" Then End

GoTo themenu:

month:

Print

Input "Month (1-12): ", mm

If mm > 12 Or mm < 1 Or Int(mm) <> mm Then Print "Months must be between 1 and 12, try again.": Print: Print: GoTo month:

Print

day:

Input "Day (1-31): ", dd

Print

Input "Year (1753-9999): ", yy

If yy < 1753 Or yy > 9999 Then Print "Year must be between 1753 and 9999. Try again.": Print: Print: GoTo month:

'Calculate to see if it's a Leap Year.

If mm <> 2 Then GoTo nex:

If yy / 400 = Int(yy / 400) Then leap = 1: GoTo more:

If yy / 4 = Int(yy / 4) Then leap = 1

If yy / 100 = Int(yy / 100) Then leap = 0



'Get the number of days for each month.

more:

If leap = 1 Then days = 29

If leap = 0 Then days = 28



GoTo weekday:

nex:

If mm = 1 Then days = 31

If mm = 3 Then days = 31

If mm = 4 Then days = 30

If mm = 5 Then days = 31

If mm = 6 Then days = 30

If mm = 7 Then days = 31

If mm = 8 Then days = 31

If mm = 9 Then days = 30

If mm = 10 Then days = 31

If mm = 11 Then days = 30

If mm = 12 Then days = 31



weekday:



If dd < 1 Or dd <> Int(dd) Or dd > days Then Print "Days must be between 1 and " + Str$(days) + " on that month. Try again.": Print: Print: GoTo day:



If mm = 1 Then month$ = "January"

If mm = 2 Then month$ = "February"

If mm = 3 Then month$ = "March"

If mm = 4 Then month$ = "April"

If mm = 5 Then month$ = "May"

If mm = 6 Then month$ = "June"

If mm = 7 Then month$ = "July"

If mm = 8 Then month$ = "August"

If mm = 9 Then month$ = "September"

If mm = 10 Then month$ = "October"

If mm = 11 Then month$ = "November"

If mm = 12 Then month$ = "December"



oldyy = yy

oldmm = mm

olddd = dd

GetDay mm, dd, yy, weekday

yy = oldyy

mm = oldmm

dd = olddd

If weekday = 1 Then weekday$ = "Sunday"

If weekday = 2 Then weekday$ = "Monday"

If weekday = 3 Then weekday$ = "Tuesday"

If weekday = 4 Then weekday$ = "Wednesday"

If weekday = 5 Then weekday$ = "Thursday"

If weekday = 6 Then weekday$ = "Friday"

If weekday = 0 Then weekday$ = "Saturday"





'--------------------------------------------------------------------------------------------------

Print: Print

Print month$ + " " + Str$(dd) + ", " + Str$(yy) + " falls on a " + weekday$ + "."

'--------------------------------------------------------------------------------------------------



Print: Print: Print

Print "Press M to go to menu or Esc to quit."

againn:

ag$ = InKey$

If ag$ = "m" Or ag$ = "M" Then GoTo start:

If ag$ = Chr$(27) Then End

GoTo againn:



leapyear:

Input "Year (1753-9999): ", yy

If yy < 1753 Or yy > 9999 Then Print "Year must be between 1753 and 9999. Try again.": Print: Print: GoTo leapyear:

'Calculate to see if it's a Leap Year.

If yy / 400 = Int(yy / 400) Then leap = 1: GoTo more2:

If yy / 4 = Int(yy / 4) Then leap = 1

If yy / 100 = Int(yy / 100) Then leap = 0



'Get the number of days for each month.

more2:

Print: Print

If leap = 1 Then Print Str$(yy) + " does have a Leap Year."

If leap = 0 Then Print Str$(yy) + " does not have a Leap Year."

Print: Print: Print

Print "Press M to go menu or Esc to quit."

again:

ag$ = InKey$

If ag$ = "m" Or ag$ = "M" Then GoTo start:

If ag$ = Chr$(27) Then End

GoTo again:



'This section gets the right weekday.

Sub GetDay (mm, dd, yy, weekday) 'use 4 digit year

    'From Zeller's congruence: https://en.wikipedia.org/wiki/Zeller%27s_congruence

    If mm < 3 Then yy = yy - 1

    If mm < 3 Then mm = mm + 12

    century = yy Mod 100

    zerocentury = yy \ 100

    weekday = (dd + Int(13 * (mm + 1) / 5) + century + Int(century / 4) + Int(zerocentury / 4) + 5 * zerocentury) Mod 7

End Sub