列表中的 VB.NET If-Else
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VB.NET If-Else in List
提问by dpp
I just want to know if there's an approach in VB.NET that can find if a specific value exist on a list or something which can use in my If-else condition. What I'm doing now is to use this:
我只想知道 VB.NET 中是否有一种方法可以找到列表中是否存在特定值或可以在我的 If-else 条件中使用的内容。我现在正在做的是使用这个：
If ToStatus = "1CE" Or ToStatus = "2TL" Or ToStatus = "2PM" Then
'Do something
Else
'Do something
End If
This works fine, but how if I have hundreds of string to compare to ToStatusin the future? It will be a nightmare! Now, if such functionality exists, how can I add "And" and "Or" in the statement?
这很好用，但是如果我ToStatus将来有数百个字符串要比较怎么办？这将是一场噩梦！现在，如果存在这样的功能，我如何在语句中添加“And”和“Or”？
Thanks in advance!
提前致谢！
回答by SLaks
You can use the Containsfunction:
您可以使用该Contains功能：
Dim someList = New List(Of String) From { ... }
If Not someList.Contains(ToStatus) Then
回答by Petr Moravek
if {"1CE","2TL","2PM"}.Contains(ToStatus)
if {"1CE","2TL","2PM"}.Contains(ToStatus)
then ..... End I
然后……结束我
回答by jusdoo
you may use select case
你可以使用选择案例
select case A
case 5,6,7,8
msgbox "you are in"
case else
msgbox "you are excluded"
end select
回答by KyleMit
Like Slaks pointed out, you can use Containson an enumerablecollection. But I think readability suffers. I don't care if some list containsmy variable; i want to know if my variable is insome list. You can wrap contains in an extension method like so:
就像Slaks 指出的那样，您可以Contains在enumerable集合上使用。但我认为可读性会受到影响。我不在乎某个列表是否包含我的变量；我想知道我的变量是否在某个列表中。您可以将 contains 包装在扩展方法中，如下所示：
Imports System.Runtime.CompilerServices
Module ExtensionMethods
<Extension()> _
Public Function [In](Of T)(ByVal item As T, ByVal ParamArray range() As T) As Boolean
Return range.Cast(Of T).Contains(item)
End Function
End Module
Then call like this:
然后像这样调用：
If ToStatus.In("1CE","2TL","2PM") Then
回答by dpp
For .NET 2.0
对于 .NET 2.0
I came across another problem where SLaks solution won't work, that is if you use .NET 2.0 where method Containsis not present. So here's the solution:
我遇到了另一个 SLaks 解决方案不起作用的问题，那就是如果您使用 .NET 2.0 而方法Contains不存在。所以这是解决方案：
If (Array.IndexOf(New String() {"1CE", "2TL", "2PM"}), ToStatus > -1) Then
'Do something if ToStatus is equal to any of the strings
Else
'Do something if ToStatus is not equal to any of the strings
End If
回答by Iladarsda
Remove duplicates from the list
从列表中删除重复项
Dim ListWithoutDuplicates As New List(Of String)
For Each item As String In ListWithDuplicates
If ListWithoutDuplicates.Contains(item) Then
' string already in a list - do nothing
Else
ListWithoutDuplicates.Add(item)
End If
Next
