vb.net 4星期二新年的时候

Question

我编写了一个支票簿应用程序，该应用程序将本月的第四个星期二存储在SQLite数据库中，当用户写入支票时，当今天的日期大于存储日期时，数据库中将更新新的第四个星期二日期，并加载一个存放SS付款的函数。

在测试过程中，我发现当年份发生变化时，我编写的第一个函数就会失败。

所以我写了第二个函数来处理这些年来的变化。

代码似乎起作用了。我想将测试合并到一个函数中，因为代码似乎不太优雅。我将张贴下面的小测试应用程序代码。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

端级

这两个函数和我只使用一个函数的测试代码注释掉了

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

终端模块

我的问题是，是否有更好的方法来编写这段代码，所以我只有一个函数？？

Answer 1

下面是一个基于传入日期的下一个月的第四个星期二的函数：

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

注意，函数总是返回下一个月的第四个星期二，它不检查传入的日期是否小于包含传入日期的同月的第四个星期二。