VB.NET相当于C＃运算符'??' [英] VB.NET equivalent of C# Operator '??'
问题描述
Hello Newsgroup，
$ c $ b存在''??''运算符。
它的用法如下： br />
string s1 = null;
string s2 = s1 ?? "（undefined）"
并执行以下操作（简化）：
if（s1 == null）
s2 ="（undefined）"
else
s2 = s1
是否有等效运算符在Visual Basic.Net中，如果是这样，它是如何调用的？
提前谢谢
Philipp
Hello Newsgroup,
in c# there exists the ''??'' operator.
It is used like this :
string s1 = null;
string s2 = s1 ?? "(undefined)"
And does the following (simplified) :
if(s1 == null)
s2 = "(undefined)"
else
s2 = s1
Is there an equivalent operator in Visual Basic.Net, and if so, how is
it called ?
Thanks in advance
Philipp
推荐答案
Philipp Brune写道：
Philipp Brune wrote:
Visual Basic中是否有等效的运算符.Net，如果是的话，怎么称它为b $ b？
Is there an equivalent operator in Visual Basic.Net, and if so, how is
it called ?
我认为你最接近的就是使用IIf：
\\\
Dim s1 As String = Nothing
Dim s2 As String = IIf（s1 Is Nothing，"（undefined）"，s1）.ToString
///
HTH，
-
（O）enone
I think the closest you''ll get to that is by using IIf:
\\\
Dim s1 As String = Nothing
Dim s2 As String = IIf(s1 Is Nothing, "(undefined)", s1).ToString
///
HTH,
--
(O)enone
我认为你最接近的就是使用IIf：
\\\
Dim s1 As String = Nothing
Dim s2 As String = IIf（s1 Is Nothing，（undefined） ;，s1）.ToString
///
I think the closest you''ll get to that is by using IIf:
\\\
Dim s1 As String = Nothing
Dim s2 As String = IIf(s1 Is Nothing, "(undefined)", s1).ToString
///
但是，什么更具可读性？这个：
如果s1什么都没有那么
s2 ="（undefined）"
Else
s2 = s1
结束如果
或者这个：
s2 = IIf（s1 Is Nothing ，（undefined），s1）.ToString
我们在工作中也讨论了这个问题并决定前者更好（在
上下文中） C ++，而不是.NET，即.z =（v< w？x：y））。这些函数可以很好地帮助混淆代码;）
Robin
Yes, however, what is more readable? This:
If s1 Is Nothing Then
s2 = "(undefined)"
Else
s2 = s1
End If
or this:
s2 = IIf(s1 Is Nothing, "(undefined)", s1).ToString
We also had this debate at work and decided the former was better (in the
context of C++, not .NET, ie. z = ( v < w ? x : y ) ). These functions do
well to help obfuscate code however ;)
Robin
Robinson写道：
Robinson wrote:
>我认为你最接近的就是使用IIf：
>I think the closest you''ll get to that is by using IIf:
但是，什么更具可读性？
Yes, however, what is more readable?
我当然会说完整版本比缩写的IIf版本更具可读性和可维护性。
就我个人而言，我通常使用IIf的唯一方法是将复数添加到状态
消息，例如：
\\\
MsgBox（" Downloaded"& msgcount&" message" ;& IIf（msgcount = 1，""，
" s"）。ToString）
///
在其他情况下（也可以说也是这个），他们几乎总是让代码更难以阅读。
-
（O）enone
I''d certainly say the "full" version is more readable and maintainable than
the abbreviated IIf version.
Personally the only thing I normally use IIf for is adding plurals to status
message, for example:
\\\
MsgBox("Downloaded " & msgcount &" message" & IIf(msgcount=1, "",
"s").ToString)
///
In other situations (and arguably in this one too) they nearly always make
the code harder to read.
--
(O)enone
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