我可以使用vb.net中的select case语句检查时隙 [英] Can i check time slot using select case statement in vb.net

问题描述

我想用半小时的时段检查当前时间（从00：00,00：30,01：00，...... 23:30共48次开始）。是否可以使用select case语句。如果没有任何其他建议，请？



我将当前时间存储在一个对象中。现在我需要对这个变量进行条件检查。



Dim datime As DateTime = DateTime.Now.ToString（t）

I want to check the current time with the half an hour time slots (total of 48 starts from 00:00,00:30,01:00,....23:30). Is it possible using select case statement. If not any other suggestions please?

I am storing the current time in an object. now i need to do conditional check on this variable.

Dim datime As DateTime = DateTime.Now.ToString("t")

推荐答案

您需要实现计时器 [< a href =http://msdn.microsoft.com/en-us/library/system.threading.timer.aspxtarget =_ blanktitle =New Window> ^ ]，它提供了按指定的时间间隔执行方法的机制。



--EDIT1 ---

好​​的，创建新的Windows应用程序项目并放置标签表格。然后复制并粘贴以下代码：

You need to implement timer[^], which provides a mechanism for executing a method at specified intervals.

--EDIT1---
OK, create new windows application project and place label on the form. Then copy and paste code below:

Public Class Form1
    Delegate Sub SetTextCallback(ByVal [text] As String)

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Create an inferred delegate that invokes methods for the timer.
        Dim tcb As TimerCallback = AddressOf CheckSendReport
        Dim oTimer As System.Threading.Timer = New System.Threading.Timer(tcb, 0, 0, 60000)
    End Sub
    
    'This method is called by the timer delegate.
    'Every (period time - in example 60000) we call DrawMessage sub
    Sub CheckSendReport(ByVal state As Object)
        Dim dTime As Date = Date.Now
        If dTime.Minute = 30 Then
            DrawMessage(dTime.ToString & " - Now!")
        Else
            DrawMessage(dTime.ToString & " - Not yet!")
        End If
    End Sub

    'draw message
    Private Sub DrawMessage(ByVal sMsg As String)
        If Me.Label1.InvokeRequired Then
            Dim d As New SetTextCallback(AddressOf DrawMessage)
            Me.Invoke(d, New Object() {sMsg})
        Else
            Me.Label1.Text = sMsg
        End If
    End Sub
End Class

我希望它有用。

I hope it's helpful.

问题是，你不想要，也不能指望一个确切的时间。你最好用



if（datime.TotalMinutes< = 30）

{

}

else if（datime.TotalMinutes< = 60）

{

}



等，而不是switch语句，这将要求您输入每个可能的值。注意我使用'TotalMinutes'如果你使用Minute，它只会达到59.

The problem is, you don't want, and can't count on, an exact time. You're better off with

if (datime.TotalMinutes <= 30)
{
}
else if (datime.TotalMinutes <= 60)
{
}

etc, instead of a switch statement, which would require you entering every possible value. Note I used 'TotalMinutes' if you used Minute, it would only go up to 59.

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