如何让DateTimePicker显示空字符串？

Question

我希望能够显示DateTimePicker默认值为nothing,即没有日期.

例如,我有一个任务的开始日期dtTaskStart和结束日期dtTaskEnd,但结束日期未知,并且最初未填充.

我已yyyy-MM-dd为两个控件指定了自定义格式.

null在运行时将值设置为或为空字符串会导致错误,因此如何实现此目的？

我曾考虑使用复选框来控制此字段的启用,但仍然存在显示初始值的问题.

编辑:
可以说是问题DateTimePicker Null Value(.NET)的副本,但我找到的问题的解决方案不是该问题的解决方案,所以我认为它应该留在这里供其他人查找..

Answer 1

只需按如下方式设置属性:

当用户按"清除键"或"删除键"时

dtpData.CustomFormat = " "  'An empty SPACE
dtpData.Format = DateTimePickerFormat.Custom

在DateTimePicker1_ValueChanged事件上做

dtpData.CustomFormat = "dd/MM/yyyy hh:mm:ss"

Answer 2

通过使用CustomFormat属性对值进行模糊处理,使用复选框cbEnableEndDate作为标志来指示其他代码是否应忽略该值:

If dateTaskEnd > Date.FromOADate(0) Then
    dtTaskEnd.Format = DateTimePickerFormat.Custom
    dtTaskEnd.CustomFormat = "yyyy-MM-dd"
    dtTaskEnd.Value = dateTaskEnd 
    dtTaskEnd.Enabled = True
    cbEnableEndDate.Checked = True
Else
    dtTaskEnd.Format = DateTimePickerFormat.Custom
    dtTaskEnd.CustomFormat = " "
    dtTaskEnd.Value = Date.FromOADate(0)
    dtTaskEnd.Enabled = False
    cbEnableEndDate.Checked = False
End If

Answer 3

这对我来说对c#有用

if (enableEndDateCheckBox.Checked == true)
{
    endDateDateTimePicker.Enabled = true;
    endDateDateTimePicker.Format = DateTimePickerFormat.Short;                
}
else
{
    endDateDateTimePicker.Enabled = false;
    endDateDateTimePicker.Format = DateTimePickerFormat.Custom;
    endDateDateTimePicker.CustomFormat = " ";
}

好一个人!

Answer 4

如果任何人在表单加载事件期间将datetimepicker控件设置为空白时出现问题,然后根据需要显示当前日期,这是一个示例:

确保CustomFormat = " "两种方法都有相同数量的空间(至少一个空格)

Private Sub setDateTimePickerBlank(ByVal dateTimePicker As DateTimePicker)    

    dateTimePicker.Visible = True
    dateTimePicker.Format = DateTimePickerFormat.Custom
    dateTimePicker.CustomFormat = "    " 
End Sub


Private Sub dateTimePicker_MouseHover(ByVal sender As Object, ByVal e As 
                    System.EventArgs) Handles dateTimePicker.MouseHover

    Dim dateTimePicker As DateTimePicker = CType(sender, DateTimePicker)
    If dateTimePicker.Text = "    " Then
        dateTimePicker.Text = Format(DateTime.Now, "MM/dd/yyyy")
    End If
End Sub