VB倒计时程序代码

答案：
代码如下：
'窗体全局变量
Dim Hours As Integer '记录小时
Dim Minutes As Integer  '记录分钟
Dim Seconds As Integer  '记录秒
Dim Time As Date  
 
Private Sub Mydisplay()
    Hours = Val(Text1.Text)
    Minutes = Val(Text2.Text)
    Seconds = Val(Text3.Text)
    Time = TimeSerial(Hours, Minutes, Seconds) '组合字符串
    '将字符串转化为时间格式
    Label1.Caption = Format$(Time, "hh") & ":" & Format$(Time, "nn") & ":" & Format$(Time, "ss")
End Sub
Private Sub Command1_Click()
    Timer1.Enabled = True
    Command1.Enabled = False
    Command2.Enabled = True
    Command3.Enabled = True
End Sub
Private Sub Command2_Click()
    If Timer1.Enabled Then
        Timer1.Enabled = False
    End If
    Hours = 0
    Minutes = 0
    Seconds = 0
    Time = 0
    Command1.Enabled = True
    Command3.Enabled = False
    Text1.Text = " "
    Text2.Text = " "
    Text3.Text = " "
    Text1.SetFocus '将焦点放到Text1控件上
End Sub
Private Sub Command3_Click()
    Timer1.Enabled = False
    Command3.Enabled = False
    Command1.Enabled = True
    Command2.Enabled = True
End Sub
Private Sub Form_Load()
    Timer1.Interval = 1000  '将Timer控件的事件引发间隔设置成1000毫秒
     '初始化变量
    Hours = 0
    Minutes = 0
    Seconds = 0
    Time = 0
End Sub
Private Sub Text1_Change()  'TextBox控件事件，当控件的Text值改变时引发该事件
    Mydisplay
End Sub
Private Sub Text2_Change()
    Mydisplay
End Sub
Private Sub Text3_Change()
    Mydisplay
End Sub
Private Sub Timer1_Timer() 'Timer控件的事件
     Timer1.Enabled = False
    If (Format$(Time, "hh") & ":" & Format$(Time, "nn") & ":" & Format$(Time, "ss")) <> "00:00:00" Then 'Counter to continue loop until 0
        Time = DateAdd("s", -1, Time)
        Label1.Caption = Format$(Time, "hh") & ":" & Format$(Time, "nn") & ":" & Format$(Time, "ss")
        Timer1.Enabled = True
    Else
        '如果未输入时间或时间为零则发出警报
        Timer1.Enabled = False
        Beep
        Beep
        Command2.Enabled = True
    End If
End Sub

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