= nothing vs. Is Nothing

**Armin Zingler** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

"Jethro" <jethro_uk@hotm ail.comschrieb

Hi guys, quick sanity check please.
>
When TESTING for nothing, it's "if <exprIs Nothing"
>
when ASSIGNING, it's "<expr= Nothing"
>
correct ?
>
so a line "If ThisValue = nothing" in some (inherited) code is a
bug, plain & simple ?

No, not a bug, but IMO an undesired feature. Nothing used with value
types is the "default value" of the value type, i.e. zero for Integers,
1/1/0001 with Dates, etc.

"If ThisValue = nothing" only works with values types (not with
reference types), so if ThisValue is an Integer, it is equal to "If
ThisValue = 0"

....But, what about putting the caret on the word Nothing and pressing
[F1]? ;-)

AZ

**Cor Ligthert[MVP]** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

The nicest example is in my opinion a string

A string that Is nothing, is not yet assigned

A string that = nothing is the same as "" and will direct before the
evaluating set to that if it "Is" nothing

This finer test is not in C* languages.

Cor

"Jethro" <jethro_uk@hotm ail.comschreef in bericht
news:kYmdnSbuX5 YkLb_VnZ2dnUVZ8 tuqnZ2d@bt.com. ..

Hi guys, quick sanity check please.
>
When TESTING for nothing, it's "if <exprIs Nothing"
>
when ASSIGNING, it's "<expr= Nothing"
>
correct ?
>
so a line "If ThisValue = nothing" in some (inherited) code is a bug,
plain
& simple ?
>
Thanks
>

**=?Utf-8?B?RGF2aWQgQW50b24=?=** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

That's quite correct - with one addition: to make things a little more
confusing, "If s = Nothing" and "If s Is Nothing" both work for strings, with
subtly different results...
--

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"Armin Zingler" wrote:

"Jethro" <jethro_uk@hotm ail.comschrieb

Hi guys, quick sanity check please.

When TESTING for nothing, it's "if <exprIs Nothing"

when ASSIGNING, it's "<expr= Nothing"

correct ?

so a line "If ThisValue = nothing" in some (inherited) code is a
bug, plain & simple ?

>
No, not a bug, but IMO an undesired feature. Nothing used with value
types is the "default value" of the value type, i.e. zero for Integers,
1/1/0001 with Dates, etc.
>
"If ThisValue = nothing" only works with values types (not with
reference types), so if ThisValue is an Integer, it is equal to "If
ThisValue = 0"
>
....But, what about putting the caret on the word Nothing and pressing
[F1]? ;-)
>
>
AZ
>
>

**Jethro** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

"Cor Ligthert[MVP]" <notmyfirstname @planet.nlwrote in message
news:4F5745FF-BD74-4255-9017-40E87BAF7F64@mi crosoft.com...

The nicest example is in my opinion a string
>
A string that Is nothing, is not yet assigned
>
A string that = nothing is the same as "" and will direct before the
evaluating set to that if it "Is" nothing
>
This finer test is not in C* languages.
>
Cor
>
>
>
>
"Jethro" <jethro_uk@hotm ail.comschreef in bericht
news:kYmdnSbuX5 YkLb_VnZ2dnUVZ8 tuqnZ2d@bt.com. ..

>Hi guys, quick sanity check please.
>>
>When TESTING for nothing, it's "if <exprIs Nothing"
>>
>when ASSIGNING, it's "<expr= Nothing"
>>
>correct ?
>>
>so a line "If ThisValue = nothing" in some (inherited) code is a bug,
>plain
>& simple ?
>>
>Thanks
>>

>

The problem I was having was a test on an integer, which had a value of 0
was equating to true ...

Dim myInt as integer =0

if myInt = Nothing then MessageBox("myI nt is showing as 'Nothing' even
thought is has a vallue of 0")

seems to print the MessageBox .....

**Cor Ligthert[MVP]** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

David,

Maybe easier, "Is" is testing a Type and "=" a value.

While "Is" nothing means in fact no object, because everything is inheriting
from object, this goes forever.

Therefore it is If dr.Items("whate ver") Is DBNull.Value then the type
DBNull.Value is tested.

While If CInt(dr.Items(" whatever")) = 0 then the value zero is tested.

Cor

"David Anton" <DavidAnton@dis cussions.micros oft.comschreef in bericht
news:831E24ED-2CEF-45D2-805A-8DE01EA3CDDC@mi crosoft.com...

That's quite correct - with one addition: to make things a little more
confusing, "If s = Nothing" and "If s Is Nothing" both work for strings,
with
subtly different results...
--

Source Code Converters

http://www.tangiblesoftwaresolutions.com

Source code converters: Convert between C#, C++, Java, VB, and Python with the most accurate and reliable source code converters

C++ to C#
C++ to VB
C++ to Java
Java to VB & C#
Instant C#: convert VB to C#
Instant VB: convert C# to VB
Instant C++: VB, C#, or Java to C++/CLI
>
>
"Armin Zingler" wrote:
>

>"Jethro" <jethro_uk@hotm ail.comschrieb

Hi guys, quick sanity check please.
>
When TESTING for nothing, it's "if <exprIs Nothing"
>
when ASSIGNING, it's "<expr= Nothing"
>
correct ?
>
so a line "If ThisValue = nothing" in some (inherited) code is a
bug, plain & simple ?

>>
>No, not a bug, but IMO an undesired feature. Nothing used with value
>types is the "default value" of the value type, i.e. zero for Integers,
>1/1/0001 with Dates, etc.
>>
>"If ThisValue = nothing" only works with values types (not with
>reference types), so if ThisValue is an Integer, it is equal to "If
>ThisValue = 0"
>>
>....But, what about putting the caret on the word Nothing and pressing
>[F1]? ;-)
>>
>>
>AZ
>>
>>

**Cor Ligthert[MVP]** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

Dim myInt as integer =0
>
if myInt = Nothing then MessageBox("myI nt is showing as 'Nothing' even
thought is has a vallue of 0")
>
seems to print the MessageBox .....

Yes of course because the default for an integer (Nothing) = 0,

If 0 = 0 then ............... .... is true

While this goes as well and is more VB style

Dim myInt as integer
if myInt = nothing then the messagebox will be showed, because myint is set
forever in this case to the default 0

Cor

**Karl Rhodes** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

On 8 May, 16:46, "Cor Ligthert[MVP]" <notmyfirstn... @planet.nlwrote :

Dim myInt as integer =0

>

if myInt = Nothing then MessageBox("myI nt is showing as 'Nothing' even
thought is has a vallue of 0")

>

seems to print the MessageBox .....

>
Yes of course because the default for an integer (Nothing) = 0,
>
If 0 = 0 then ............... .... is true
>
While this goes as well and is more VB style
>
Dim myInt as integer
if myInt = nothing then the messagebox will be showed, because myint is set
forever in this case to the default 0
>
Cor

If you're using VB the why not use the IsNothing Method?

if IsNothing(myInt ) then MessageBox.Show ....

**Armin Zingler** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

"Karl Rhodes" <googlegroups@c ortexa.co.uksch rieb

If you're using VB the why not use the IsNothing Method?
>
if IsNothing(myInt ) then MessageBox.Show ....

Why call a function that does the comparision instead of doing the
comparison?

Armin

**Jethro** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

"Karl Rhodes" <googlegroups@c ortexa.co.ukwro te in message
news:c1bcba36-f2a2-4065-9479-7f60575f232f@r6 6g2000hsg.googl egroups.com...

On 8 May, 16:46, "Cor Ligthert[MVP]" <notmyfirstn... @planet.nlwrote :

Dim myInt as integer =0

>>

if myInt = Nothing then MessageBox("myI nt is showing as 'Nothing' even
thought is has a vallue of 0")

>>

seems to print the MessageBox .....

>>
>Yes of course because the default for an integer (Nothing) = 0,
>>
>If 0 = 0 then ............... .... is true
>>
>While this goes as well and is more VB style
>>
>Dim myInt as integer
>if myInt = nothing then the messagebox will be showed, because myint is
>set
>forever in this case to the default 0
>>
>Cor

>
If you're using VB the why not use the IsNothing Method?
>
if IsNothing(myInt ) then MessageBox.Show ....

As I said, inherited code...

**Cor Ligthert[MVP]** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

>
As I said, inherited code...

No you said,

>so a line "If ThisValue = nothing" in some (inherited) code is a bug,

plain & simple ?

The "Is" is about objects, while you can test everything as object, as that
is the base for every class in Net.
(The so often used ToString is a method from object and therefore a method
from everything).

If this Value = nothing has nothing to do with inherited code.

However why did you get the idea that this is a bug?

Cor

**Jethro** · Jun 27 '08, 08:14 PM

Re: = nothing vs. Is Nothing

"Cor Ligthert[MVP]" <notmyfirstname @planet.nlwrote in message
news:39F15764-FA45-482B-8380-C33186A49AEF@mi crosoft.com...

>

>>
>As I said, inherited code...

>
No you said,
>

so a line "If ThisValue = nothing" in some (inherited) code is a bug,

plain & simple ?
>
The "Is" is about objects, while you can test everything as object, as
that is the base for every class in Net.
(The so often used ToString is a method from object and therefore a method
from everything).
>
If this Value = nothing has nothing to do with inherited code.
>
However why did you get the idea that this is a bug?

ROTFL !

Sorry, bad choice of words. What I meant is that I have just started a new
job, and am picking up the code left by the previous developer - therefore
*I* "inherited" it.

Nice to go home with a laugh - thanks for your input, hope you have a good
weekend !

= nothing vs. Is Nothing

= nothing vs. Is Nothing

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