.net - 如何查找两个日期/DateTimePicker 之间的天数

Question

在我下面的代码中，我如何设置到达日期和出发日期，以便我可以获得应付金额？我需要将它们设置为在酒店入住的天数，以便我可以得出总数。如果这有意义吗？我在 Visual Basic 中使用日期时间选择器。

Public Class RentalForm
    'declare constants
    Const tax_rate_decimal As Decimal = 12.25D
    Const king_price_decimal As Decimal = 110.9D
    Const queen_price_decimal As Decimal = 105.9D
    Const double_price_decimal As Decimal = 95.9D

    'declare variables
    Private roomchargesumdecimal, taxamountsumdecimal, amountduesumdecimal As Decimal

    Private Sub exitButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles exitButton.Click
        Close()
    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBoxnameofguest.TextChanged

    End Sub

    Private Sub calculateButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles calculateButton.Click
        'dimension local variables
        Dim numberofguestsinteger As Integer
        Dim roomchargedecimal, taxamountdecimal, amountduedecimal, taxratedecimal As Integer
        Dim arrivaldate, departuredate As Date

        Try
            'dates
            arrivaldate = Now

            'convert quantity to numeric
            numberofguestsinteger = Integer.Parse(TextBoxNumberofguests.Text)

            'calculate values for single person
            roomchargedecimal = numberofguestsinteger * (arrivaldate + departuredate)
            taxratedecimal = roomchargedecimal * tax_rate_decimal   

        Catch ex As Exception

        End Try

    End Sub

    Private Sub DateTimePickerarrivaldate_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DateTimePickerarrivaldate.ValueChanged

    End Sub

    Private Sub Label16averagelengthofstay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label16averagelengthofstay.Click


    End Sub

    Private Sub RentalForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub
End Class              

Answer 1

DateTime数学起初可能会令人困惑。但它们是否是 DateTimePicker 并不重要控件或变量，因为 myDateTimePicker.Value 是 DateTime类型。因此，您可以混合和匹配变量和控件，例如 Arrival as Now 和 Departure from a picker，只需使用减法:

Dim arrivaldate As DateTime = DateTime.Now
Dim departuredate As DateTime = Me.DeparturePicker.Value

Dim DaysStayed as Int32 = departuredate.Subtract(arrivaldate).Days

要记住的是，结果是 TimeSpan目的。如果您查看结构，您会看到它提供了从 Days 开始的时间单位。至 Ticks .

上面的代码提取了 Days来自 TimeSpan 的值不创建临时文件 TimeSpan变种其它的办法:

Dim tsHotelStay = detarturedate.Value - arrivalDate
wholeDays = tsHotelStay.Days              ' e.g 7
totalDays = tsHotelStay.TotalDays         . e.g. 7.53
totalHrs = tsHotelStay.TotalHours         . eg 180.397

这一次，代码确实创建了一个 TimeSpan变量 ( tsHotelDay )。请注意，所有属性都有整数和小数形式(Ticks 除外)。

最后，所示的 2 个减法方法( DateTime.Subtract(dt) 和 myTs = dtA - dtB )在功能上是相同的:都返回一个 TimeSpan 对象。