EXCEL-VBA函數：公曆轉農曆，返回格式YYYY-MM-DD

VBA調用：MsgBox Gong2Lunar("1981-08-26")

公式調用＝Gong2Lunar("1981-08-26")

Public Function Gong2Lunar(Optional Gong As Date) As String
    Dim MonthAdd(11), NongliData(99), TianGan(9), DiZhi(11), ShuXiang(11)
    Dim curTime, curYear, curMonth, curDay
    Dim GongliStr, NongliStr, NongliDayStr
    Dim i, m, n, k, isEnd, bit, TheDate
    
    '獲取當前系統時間
    curTime = Gong
    
    '公曆每月前面的天數
    MonthAdd(0) = 0
    MonthAdd(1) = 31
    MonthAdd(2) = 59
    MonthAdd(3) = 90
    MonthAdd(4) = 120
    MonthAdd(5) = 151
    MonthAdd(6) = 181
    MonthAdd(7) = 212
    MonthAdd(8) = 243
    MonthAdd(9) = 273
    MonthAdd(10) = 304
    MonthAdd(11) = 334
    '農曆數據
    NongliData(0) = 2635
    NongliData(1) = 333387
    NongliData(2) = 1701
    NongliData(3) = 1748
    NongliData(4) = 267701
    NongliData(5) = 694
    NongliData(6) = 2391
    NongliData(7) = 133423
    NongliData(8) = 1175
    NongliData(9) = 396438
    NongliData(10) = 3402
    NongliData(11) = 3749
    NongliData(12) = 331177
    NongliData(13) = 1453
    NongliData(14) = 694
    NongliData(15) = 201326
    NongliData(16) = 2350
    NongliData(17) = 465197
    NongliData(18) = 3221
    NongliData(19) = 3402
    NongliData(20) = 400202
    NongliData(21) = 2901
    NongliData(22) = 1386
    NongliData(23) = 267611
    NongliData(24) = 605
    NongliData(25) = 2349
    NongliData(26) = 137515
    NongliData(27) = 2709
    NongliData(28) = 464533
    NongliData(29) = 1738
    NongliData(30) = 2901
    NongliData(31) = 330421
    NongliData(32) = 1242
    NongliData(33) = 2651
    NongliData(34) = 199255
    NongliData(35) = 1323
    NongliData(36) = 529706
    NongliData(37) = 3733
    NongliData(38) = 1706
    NongliData(39) = 398762
    NongliData(40) = 2741
    NongliData(41) = 1206
    NongliData(42) = 267438
    NongliData(43) = 2647
    NongliData(44) = 1318
    NongliData(45) = 204070
    NongliData(46) = 3477
    NongliData(47) = 461653
    NongliData(48) = 1386
    NongliData(49) = 2413
    NongliData(50) = 330077
    NongliData(51) = 1197
    NongliData(52) = 2637
    NongliData(53) = 268877
    NongliData(54) = 3365
    NongliData(55) = 531109
    NongliData(56) = 2900
    NongliData(57) = 2922
    NongliData(58) = 398042
    NongliData(59) = 2395
    NongliData(60) = 1179
    NongliData(61) = 267415
    NongliData(62) = 2635
    NongliData(63) = 661067
    NongliData(64) = 1701
    NongliData(65) = 1748
    NongliData(66) = 398772
    NongliData(67) = 2742
    NongliData(68) = 2391
    NongliData(69) = 330031
    NongliData(70) = 1175
    NongliData(71) = 1611
    NongliData(72) = 200010
    NongliData(73) = 3749
    NongliData(74) = 527717
    NongliData(75) = 1452
    NongliData(76) = 2742
    NongliData(77) = 332397
    NongliData(78) = 2350
    NongliData(79) = 3222
    NongliData(80) = 268949
    NongliData(81) = 3402
    NongliData(82) = 3493
    NongliData(83) = 133973
    NongliData(84) = 1386
    NongliData(85) = 464219
    NongliData(86) = 605
    NongliData(87) = 2349
    NongliData(88) = 334123
    NongliData(89) = 2709
    NongliData(90) = 2890
    NongliData(91) = 267946
    NongliData(92) = 2773
    NongliData(93) = 592565
    NongliData(94) = 1210
    NongliData(95) = 2651
    NongliData(96) = 395863
    NongliData(97) = 1323
    NongliData(98) = 2707
    NongliData(99) = 265877
    '生成當前公曆年、月、日 ==> GongliStr
    curYear = Year(curTime)
    curMonth = Month(curTime)
    curDay = Day(curTime)
    GongliStr = curYear & "年"
    If (curMonth < 10) Then
        GongliStr = GongliStr & "0" & curMonth & "月"
    Else
        GongliStr = GongliStr & curMonth & "月"
    End If
    If (curDay < 10) Then
        GongliStr = GongliStr & "0" & curDay & "日"
    Else
        GongliStr = GongliStr & curDay & "日"
    End If
    '計算到初始時間1921年2月8日的天數：1921-2-8(正月初一)
    TheDate = (curYear - 1921) * 365 + Int((curYear - 1921) / 4) + curDay + MonthAdd(curMonth - 1) - 38
    If ((curYear Mod 4) = 0 And curMonth > 2) Then
        TheDate = TheDate + 1
    End If
    '計算農曆天干、地支、月、日
    isEnd = 0
    m = 0
    Do
        If (NongliData(m) < 4095) Then
            k = 11
        Else
            k = 12
        End If
        n = k
        Do
        If (n < 0) Then
            Exit Do
        End If
        '獲取NongliData(m)的第n個二進制位的值
        bit = NongliData(m)
        For i = 1 To n Step 1
            bit = Int(bit / 2)
        Next
        bit = bit Mod 2
        If (TheDate <= 29 + bit) Then
            isEnd = 1
            Exit Do
        End If
        TheDate = TheDate - 29 - bit
        n = n - 1
        Loop
        If (isEnd = 1) Then
            Exit Do
        End If
        m = m + 1
    Loop
    curYear = 1921 + m
    curMonth = k - n + 1
    curDay = TheDate
    If (k = 12) Then
        If (curMonth = (Int(NongliData(m) / 65536) + 1)) Then
            curMonth = 1 - curMonth
        ElseIf (curMonth > (Int(NongliData(m) / 65536) + 1)) Then
            curMonth = curMonth - 1
        End If
    End If
    
    curMonth = Abs(curMonth)
    
    Gong2Lunar = curYear & "-" & IIf(curMonth < 10, "0", "") & curMonth & "-" & IIf(curDay < 10, "0", "") & curDay
End Function