vb.net 新年第4个星期二

Question

我编写了一个支票簿应用程序，它将每月的第 4 个星期二存储在 SQLite 数据库中，当用户写支票并且今天的日期大于存储的日期时，数据库中更新了新的第 4 个星期二日期和 function 到存款 SS 付款已加载。
在测试时，我发现当年份更改时，我写的第一个 Function 会失败。
所以我写了第二个 Function 来处理年的变化。
该代码似乎正在工作。 我想将测试合并到一个 Function 中，因为代码看起来不够优雅。 我将在下面发布小型 TEST 应用程序代码。 这两个功能在一个模块中。

Public Class frmStart
Dim varSearchDate As Date
Dim varFTue As Date

Private Sub frmStart_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    tbBox1.Text = "2021-12-28" ' 2021-11-23 2021-12-28 TEST DATES
End Sub

Private Sub btnADD_Click(sender As Object, e As EventArgs) Handles btnADD.Click
    varSearchDate = CDate(tbBox1.Text)
    tbAns.Text = varSearchDate.ToString("M-d-yyyy")

    Dim dateToday = Date.Today
    Dim mo As String
    mo = varSearchDate.ToString("MM")

    If dateToday > varSearchDate And CInt(mo) <> 12 Then
        varFTue = CDate(FourthTueOfNextMonth(Date.Today).ToString("yyyy-M-d"))
        MsgBox("varFTue Next Mo " & varFTue)
        tbBox2.Text = varFTue.ToString("yyyy-M-d")
        'WriteNewFourthTue()
        'gvTxType = "SS Deposit"
    ElseIf dateToday > varSearchDate And CInt(mo) = 12 Then
        varFTue = CDate(FourthTueOfNewYear(Date.Today).ToString("yyyy-M-d"))
        MsgBox("varFTue New Yr " & varFTue)
        tbBox3.Text = varFTue.ToString("yyyy-M-d")
        'WriteNewFourthTue()
        'gvTxType = "SS Deposit"
    End If
End Sub

结束 Class

两个 function 和我的 TEST 代码仅使用一个 FUNCTION 注释掉

Module FunctionModule

'Function FourthTueOfNextMonth(dt As Date) As Date
'    Dim currDate = New Date(dt.Year, dt.Month, 1)
'    Dim nTuesday As Integer
'    While nTuesday < 4
'        If currDate.DayOfWeek = DayOfWeek.Tuesday Then
'            nTuesday += 1
'        End If
'        currDate = currDate.AddDays(1)
'    End While
'    If dt.Month <> 12 Then
'        Return New Date(dt.Year, dt.Month, currDate.Day - 1)
'    ElseIf dt.Month = 12 Then
'        Return New Date(dt.Year + 1, dt.Month - 11, currDate.Day - 1)
'    End If
'End Function

Function FourthTueOfNextMonth(dt As Date) As Date
    Dim currDate = New Date(dt.Year, dt.Month, 1)
    Dim nTuesday As Integer

    While nTuesday < 4
        If currDate.DayOfWeek = DayOfWeek.Tuesday Then
            nTuesday += 1
        End If
        currDate = currDate.AddDays(1)
    End While

    Return New Date(dt.Year, dt.Month, currDate.Day - 1)

End Function

Function FourthTueOfNewYear(dt As Date) As Date
    Dim currDate = New Date(dt.Year + 1, dt.Month - 11, 1)
    Dim nTuesday As Integer

    While nTuesday < 4
        If currDate.DayOfWeek = DayOfWeek.Tuesday Then
            nTuesday += 1
        End If
        currDate = currDate.AddDays(1)
    End While

    Return New Date(dt.Year + 1, dt.Month - 11, currDate.Day - 1)

End Function

端模块

我的问题有没有更好的方法来编写这段代码，所以我只有一个 Function？

Answer 1

这是一个 function，它根据传入的日期查找下个月的第四个星期二：

Function FourthTueOfNextMonth(dt As Date) As Date
    ' Start with the First Day of the Month, from the date passed in.
    ' Add one Month to that to get the first Day of the NEXT month.
    Dim currDate As Date = (New Date(dt.Year, dt.Month, 1)).AddMonths(1)
    ' Find the First Tuesday of the Month
    While currDate.DayOfWeek <> DayOfWeek.Tuesday
        currDate = currDate.AddDays(1)
    End While
    ' Add three more Weeks to jump to Fourth Tuesday
    Return currDate.AddDays(21)
End Function

请注意，function 始终返回下个月的第四个星期二，并且它不会检查传入的日期是否小于包含传入日期的同月第四个星期二。