Question

我有3个from package import *，一个用于设置日期，第二个用于添加3天，第三个用于添加5个工作日。但是我的代码没有正确计算。我计算“手动”未来几天增加或减少当天的日子。

DateTimePicker

Answer 1

以下是一种扩展方法，您可以调用AddDays：

Imports System.Runtime.CompilerServices

Public Module DateTimeExtensions

    <Extension>
    Public Function AddWeekDays(source As Date, value As Integer) As Date
        Dim result = source

        Do
            result = result.AddDays(1)

            If result.IsWeekDay() Then
                value -= 1
            End If
        Loop Until value = 0

        Return result
    End Function

    <Extension>
    Public Function IsWeekDay(source As Date) As Boolean
        Return source.DayOfWeek <> DayOfWeek.Saturday AndAlso
               source.DayOfWeek <> DayOfWeek.Sunday
    End Function

End Module

然后你可以这样称呼：

DateTimePicker3.Value = DateTimePicker1.Value.AddWeekDays(latedlvy)

请注意，与Date.AddDays不同，该方法需要Integer而不是Double。此外，它只适用于正值。可以改进它以与AddDays完全相同的方式工作，但在这种情况下你可能不需要它。

如果您不确定扩展方法的工作原理，我建议您对该主题进行一些阅读。

编辑：我已经对此方法做了一些工作并对其进行了大幅改进。它现在处理负值和小数值，就像Date.AddDays一样。

Imports System.Runtime.CompilerServices

''' <summary>
''' Contains methods that extend the <see cref="DateTime"/> structure.
''' </summary>
Public Module DateTimeExtensions

    ''' <summary>
    ''' Gets a value indicating whether a <see cref="DateTime"/> value represents a week day.
    ''' </summary>
    ''' <param name="source">
    ''' The input <see cref="DateTime"/>, which acts as the <b>this</b> instance for the extension method.
    ''' </param>
    ''' <returns>
    ''' <b>true</b> if the represents a week day; otherwise <b>false</b>.
    ''' </returns>
    ''' <remarks>
    ''' All days other than Saturday and Sunday are considered week days.
    ''' </remarks>
    <Extension>
    Public Function IsWeekDay(source As Date) As Boolean
        Return source.DayOfWeek <> DayOfWeek.Saturday AndAlso
               source.DayOfWeek <> DayOfWeek.Sunday
    End Function

    ''' <summary>
    ''' Returns a new <see cref="DateTime"/> that adds the specified number of week days to a specified value.
    ''' </summary>
    ''' <param name="source">
    ''' The input <see cref="DateTime"/>, which acts as the <b>this</b> instance for the extension method.
    ''' </param>
    ''' <param name="value">
    ''' A number of whole and fractional days. The <i>value</i> parameter can be negative or positive.
    ''' </param>
    ''' <returns>
    ''' An object whose value is the sum of the date and time represented by this instance and the number of week days represented by <i>value</i>.
    ''' </returns>
    ''' <remarks>
    ''' All days other than Saturday and Sunday are considered week days.
    ''' </remarks>
    <Extension>
    Public Function AddWeekDays(source As Date, value As Double) As Date
        'A unit will be +/- 1 day.
        Dim unit = Math.Sign(value) * 1.0

        'Start increasing the date by units from the initial date.
        Dim result = source

        'When testing for zero, allow a margin for precision error.
        Do Until Math.Abs(value) < 0.00001
            If Math.Abs(value) < 1.0 Then
                'There is less than one full day to add so we need to see whether adding it will take us past midnight.
                Dim temp = result.AddDays(value)

                If temp.Date = result.Date OrElse temp.IsWeekDay() Then
                    'Adding the partial day did not take us into a weekend day so we're done.
                    result = temp
                    value = 0.0
                Else
                    'Adding the partial day took us into a weekend day so we need to add another day.
                    result = result.AddDays(unit)
                End If
            Else
                'Add a single day.
                result = result.AddDays(unit)

                If result.IsWeekDay() Then
                    'Adding a day did not take us into a weekend day so we can reduce the remaining value to add.
                    value -= unit
                End If
            End If
        Loop

        Return result
    End Function

End Module

Answer 2

这是另一种方法。我认为这是相当直接的 - 特别是如果你只做了几次计算。

Dim someDate As DateTime = DateTime.Now.Date

Dim dates = _
        Enumerable _
            .Range(1, 100000) _
            .Select(Function (x) someDate.AddDays(x)) _
            .Where(Function (x) x.DayOfWeek <> DayOfWeek.Saturday) _
            .Where(Function (x) x.DayOfWeek <> DayOfWeek.Sunday)

Dim nextDate = dates.Take(5).First()

这种方法的一大优势是您还可以添加更多.Where次来取消公众假期。

简单。

增加几天避免周末

2 个答案: