"Not ... Is Nothing" versus "... IsNot Nothing"
Solution 1
The
If Not var1 Is Nothing Then
Is a hangover from VB6. There didn't used to be an IsNot, and so this was the only way to determine if a variable was not Nothing
. It seems to be redundant in VB.NET.
Solution 2
foo IsNot Nothing
The following line is straight from Microsoft's Visual Basic Coding Conventions:
Use the
IsNot
keyword instead ofNot
...Is Nothing.
Solution 3
I would go with the first variant - it reads like English and is easier to follow/understand than the second one. Other than that, they are equivalent.
Solution 4
I found a similar question here VB.NET - IsNothing versus Is Nothing, where I feel this question was exhaustively answered. Among the answers Jack Snipes identified http://weblogs.asp.net/psteele/410336, a blog that gives some extra detail. From those I prefer and have used
IsNot Nothing
which also makes my code easier to read and understand.
nnnn
I am Programmer. I am Buddhist,I love art & my friend. My super power is sleeping. =)
Updated on July 09, 2022Comments
-
nnnn almost 2 years
Does anyone here use VB.NET and have a strong preference for or against using
Not foo Is Nothing
as opposed tofoo IsNot Nothing
? If so, why?For Example
If var1 IsNot Nothing Then ... End If
and
If Not var1 Is Nothing Then ... End If
I just want to know which one is better?
Are they both equally acceptable? -
Tim Schmelter about 10 years
IsNot
is a newer operator that didn't exist in pre .NET2 versions. -
EKW over 8 years"Not...Is Nothing" is not the same thing as "Not IsNothing(...)" Not outright wrong, but not an answer for this question.
-
Breeze almost 8 years"
If var1 IsNot Nothing Then
generates a Compile error" of course it does, when there is no statement or block afterwards.var1 IsNot Nothing
itself will work. You also fail to show whatNot var1 Is Nothing
does, so you don't really answer the question. And please fix your formatting -
Syroot over 7 yearsI wonder if it's actually faster or compiles to the same. I mean,
Not x Is Nothing
first does a check for type equality, then negates it.x IsNot Nothing
does only a check for type unequality which the runtime might be capable of doing faster (dumbly imaginable as if it checks a type field by field and can leave by the first non-matching one rather than going through each field to check for equality - on top just to negate the result eventually).