calendar

Option Explicit

Dim days As Long '<-Stores the number of days elapsed from 1/1/1900 to current month and year
Dim i As Integer

Private Sub cmdGenerate_Click()
On Error GoTo Error_handle 'On error, goto to end of function
days = 0
For i = 0 To 34
  Label1(i).Caption = "" 'Clear all the labels
Next i

For i = 1900 To txtYear.Text - 1
  If i Mod 4 = 0 Then 'If leap year then count 366 days
  days = days + 366
  Else 'else 365 days
  days = days + 365
  End If
Next i

For i = 1 To txtMonth.Text - 1
  If i = 1 Or i = 3 Or i = 5 Or i = 7 Or i = 8 Or i = 10 Or i = 12 Then 'For January,March,May....,December count 31 days
  days = days + 31
  ElseIf (i = 4 Or i = 6 Or i = 9 Or i = 11) Then 'For April,June,September,November count 30 days
  days = days + 30
  ElseIf (i = 2 And txtYear.Text Mod 4 = 0) Then 'If month is February and year is leap year count 29 days
  days = days + 29
  Else 'If month is February and year is not a leap year, count 28 days
  days = days + 28
  End If
 Next i

  If (i = 1 Or i = 3 Or i = 5 Or i = 7 Or i = 8 Or i = 10 Or i = 12) Then
  show_calender 31 'Show calender with 31 days
  ElseIf (i = 4 Or i = 6 Or i = 9 Or i = 11) Then
  show_calender 30 'Show calender with 30 days
  ElseIf (i = 2 And txtYear.Text Mod 4 = 0) Then
  show_calender 29 'Show calender with 29 days
  Else
  show_calender 28 'Show calender with 28 days
  End If
Error_handle:
End Sub

Private Function show_calender(n As Integer) '//<- n stores the number of days to display
Dim i, k As Integer
k = days Mod 7 'Divide days with 7, the remainder give the current day
For i = 1 To n
  Label1(k).Caption = i 'Display the number in calender format
  k = k + 1
  If k = 35 Then k = 0
Next i
End Function