Question

这是我的代码 -

            Dim provider As CultureInfo = CultureInfo.InvariantCulture
            Dim a1 As DateTime = Nothing
            insexp = DateTime.ParseExact(date1.SelectedValue, "MMMM yyyy", provider)
            If a1.Month = Today.Month AndAlso a1.Year = Today.Year Then
                a1 = Today.Date
            End If

仅当date1.selectedvalue不为null时才会起作用，但如果为null则会崩溃。如果条件不运行，我该怎么办？感谢

Answer 1

If date1.SelectedValue IsNot Nothing Then
    ...
End If

Answer 2

 Dim provider As CultureInfo = CultureInfo.InvariantCulture
        Dim a1 As DateTime = Nothing
        If not String.IsNullOrEmpty(date1.SelectedValue) Then         
    insexp = DateTime.ParseExact(date1.SelectedValue, "MMMM yyyy", provider)
         End If
    If a1.Month = Today.Month AndAlso a1.Year = Today.Year Then
        a1 = Today.Date
    End If

vb .net null条件

2 个答案: