如何显示错误信息，当用户选择超过1天，然后单击半日的复选框?

Question

我有两个日期选择器datepickerFrom和datepickerto。我想显示一个错误信息，当用户选择超过1天，并检查半天复选框，然后点击按钮提交，它将显示和错误信息。

例如:A选择1/6/2022 - 3/6/2022，然后A选择半天。当A点击提交按钮时，它会显示一条错误信息，如"对不起，您不能为半天选择超过1个日期!"'

这是我检查错误的代码

Private Function ErrorFree() As Boolean 
If datepickerFrom.Date > datepickerto.Date Then 
If chkHalfDay.Checked = True Then 
DisplayMessage("error", "ERROR", "Sorry, You can't pick more than 1 date for half day!")
Return False
Exit Function
End If
End If
Return True
End Function

Answer 1

我终于得到了答案!这是代码。然后在datepickerFrom_DateChanged和datepickerto_DateChanged中调用函数。

Private Function CalculateDaysBetweenDates() As Integer
Dim dateFrom As DateTime = Convert.ToDateTime(datepickerFrom.Date)
Dim dateTo As DateTime = Convert.ToDateTime(datepickerto.Date)
Dim ts As TimeSpan = dateTo.Subtract(dateFrom)
If Convert.ToInt32(ts.Days) > 0 Then
radHalfday.Enabled = False
Else
radHalfday.Enabled = True
End If
Return 1
End Function