Visual Basic Or,OrElse仍然返回false

Question

我是VB.net的新手,我对这个语句没什么问题,我想抛出msgBox只是因为在txtBox中txtTitul不是"Bc".或""或"Ing." ...而且每次都会抛出msgBox

If Not txtTitul.Text.Equals("Bc.") _
    OrElse Not txtTitul.Text.Equals("") _
    OrElse Not txtTitul.Text.Equals("Bc.") _
    OrElse Not txtTitul.Text.Equals("Mgr.") _
    OrElse Not txtTitul.Text.Equals("Ing.") _
    OrElse Not txtTitul.Text.Equals("Mgr. art.") _
    OrElse Not txtTitul.Text.Equals("Ing. arch.") _
    OrElse Not txtTitul.Text.Equals("MUDr.") _
    OrElse Not txtTitul.Text.Equals("MVDr.") _
    OrElse Not txtTitul.Text.Equals("RNDr.") _
    OrElse Not txtTitul.Text.Equals("PharmDr.") _
    OrElse Not txtTitul.Text.Equals("PhDr.") _
    OrElse Not txtTitul.Text.Equals("JUDr.") _
    OrElse Not txtTitul.Text.Equals("PaedDr.") _
    OrElse Not txtTitul.Text.Equals("ThDr.") Then
    MsgBox("Neplatny titul!")
    Exit Sub
End If

Answer 1

你不想用OrElse,但是AndAlso,因为只有当它不是其中的一个它是一个无效的标题(所以不是第一次和不第二次和没有第三和等....).

但是,我可以向您展示一种更简单,更易于维护的方法吗？

Dim allowedTitles = {"Bc.","Ing.","Ing. arch.","MUDr.","MVDr.","RNDr.","PhDr.","PaedDr.","ThDr."}
If Not allowedTitles.Contains(txtTitul.Text) Then 
    MsgBox("Invalid title!")
End If

如果你也想接受小写,那么忽略大小写,你可以使用:

If Not allowedTitles.Contains(txtTitul.Text, StringComparer.InvariantCultureIgnoreCase) Then 
    MsgBox("Invalid title!")
End If