Hello,

I have the following:
If MyTag Is Nothing Then
...
End If

I am getting an error.

MyTag is of type HtmlTextWriterTag

Private MyTag As HtmlTextWriterTag

How can I check if a value was given to MyTag or not?

Thanks,
Miguel

If IsNothing(MyTag) Then
. . .
End If

"shapper" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hello,
>
> I have the following:
> If MyTag Is Nothing Then
> ...
> End If
>
> I am getting an error.
>
> MyTag is of type HtmlTextWriterTag
>
> Private MyTag As HtmlTextWriterTag
>
> How can I check if a value was given to MyTag or not?
>
> Thanks,
> Miguel
>

Use "x = Nothing" for value types and "x Is Nothing" for reference types.
This will return true if x is set to it's default value. (a further
complication is that you can use both for strings, but that's a story for
another day).
--
David Anton
www.tangiblesoftwaresolutions.com
Instant C#: VB to C# converter
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"shapper" wrote:

> Hello,
>
> I have the following:
> If MyTag Is Nothing Then
> ...
> End If
>
> I am getting an error.
>
> MyTag is of type HtmlTextWriterTag
>
> Private MyTag As HtmlTextWriterTag
>
> How can I check if a value was given to MyTag or not?
>
> Thanks,
> Miguel
>
>

That's just another form of "MyTag Is Nothing", which won't work for value
types.
--
David Anton
www.tangiblesoftwaresolutions.com
Instant C#: VB to C# converter
Instant VB: C# to VB converter
C++ to C# Converter: converts C++ to C#
Instant C++: converts C# or VB to C++/CLI


"Scott M." wrote:

> If IsNothing(MyTag) Then
> . . .
> End If
>
> "shapper" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
> > Hello,
> >
> > I have the following:
> > If MyTag Is Nothing Then
> > ...
> > End If
> >
> > I am getting an error.
> >
> > MyTag is of type HtmlTextWriterTag
> >
> > Private MyTag As HtmlTextWriterTag
> >
> > How can I check if a value was given to MyTag or not?
> >
> > Thanks,
> > Miguel
> >
>
>
>

On May 30, 3:08 pm, David Anton <DavidAn...@discussions.microsoft.com>
wrote:
> That's just another form of "MyTag Is Nothing", which won't work for value
> types.
> --
> David Antonwww.tangiblesoftwaresolutions.com
> Instant C#: VB to C# converter
> Instant VB: C# to VB converter
> C++ to C# Converter: converts C++ to C#
> Instant C++: converts C# or VB to C++/CLI
>
> "Scott M." wrote:
> > If IsNothing(MyTag) Then
> > . . .
> > End If
>
> > "shapper" <mdmo...@gmail.com> wrote in message
> >news:(E-Mail Removed)...
> > > Hello,
>
> > > I have the following:
> > > If MyTag Is Nothing Then
> > > ...
> > > End If
>
> > > I am getting an error.
>
> > > MyTag is of type HtmlTextWriterTag
>
> > > Private MyTag As HtmlTextWriterTag
>
> > > How can I check if a value was given to MyTag or not?
>
> > > Thanks,
> > > Miguel

David,

I got lost. You mean I should use:
If MyTag = Nothing Then ...

Is that right?

Thanks,
Miguel

Exactly. This will work for variable of any value type, including enums.
--
David Anton
www.tangiblesoftwaresolutions.com
Instant C#: VB to C# converter
Instant VB: C# to VB converter
C++ to C# Converter: converts C++ to C#
Instant C++: converts C# or VB to C++/CLI


"shapper" wrote:

> On May 30, 3:08 pm, David Anton <DavidAn...@discussions.microsoft.com>
> wrote:
> > That's just another form of "MyTag Is Nothing", which won't work for value
> > types.
> > --
> > David Antonwww.tangiblesoftwaresolutions.com
> > Instant C#: VB to C# converter
> > Instant VB: C# to VB converter
> > C++ to C# Converter: converts C++ to C#
> > Instant C++: converts C# or VB to C++/CLI
> >
> > "Scott M." wrote:
> > > If IsNothing(MyTag) Then
> > > . . .
> > > End If
> >
> > > "shapper" <mdmo...@gmail.com> wrote in message
> > >news:(E-Mail Removed)...
> > > > Hello,
> >
> > > > I have the following:
> > > > If MyTag Is Nothing Then
> > > > ...
> > > > End If
> >
> > > > I am getting an error.
> >
> > > > MyTag is of type HtmlTextWriterTag
> >
> > > > Private MyTag As HtmlTextWriterTag
> >
> > > > How can I check if a value was given to MyTag or not?
> >
> > > > Thanks,
> > > > Miguel
>
> David,
>
> I got lost. You mean I should use:
> If MyTag = Nothing Then ...
>
> Is that right?
>
> Thanks,
> Miguel
>
>

shapper wrote:
> Hello,
>
> I have the following:
> If MyTag Is Nothing Then
> ...
> End If
>
> I am getting an error.
>
> MyTag is of type HtmlTextWriterTag
>
> Private MyTag As HtmlTextWriterTag
>
> How can I check if a value was given to MyTag or not?
>
> Thanks,
> Miguel
>

HtmlTextWriterTag is an enumeration, so the value can never be Nothing.
A value type always has a value, so you can never check if it has been
given a value or not.

The default value of a HtmlTextWriterTag variable is
HtmlTextWriterTag.Unknown. This is the value that the variable will have
if it has not been assigned any value.

--
Göran Andersson
_____
http://www.guffa.com

In VB, "Nothing" is always a shortcut to the default value of a type, whether
the type is a ref type or value type. You just have to use "Is" with ref
types and "=" with value types. This is far more general than the C# "null",
which doesn't apply at all to value types.
--
David Anton
www.tangiblesoftwaresolutions.com
Instant C#: VB to C# converter
Instant VB: C# to VB converter
C++ to C# Converter: converts C++ to C#
Instant C++: converts C# or VB to C++/CLI


"Göran Andersson" wrote:

> shapper wrote:
> > Hello,
> >
> > I have the following:
> > If MyTag Is Nothing Then
> > ...
> > End If
> >
> > I am getting an error.
> >
> > MyTag is of type HtmlTextWriterTag
> >
> > Private MyTag As HtmlTextWriterTag
> >
> > How can I check if a value was given to MyTag or not?
> >
> > Thanks,
> > Miguel
> >
>
> HtmlTextWriterTag is an enumeration, so the value can never be Nothing.
> A value type always has a value, so you can never check if it has been
> given a value or not.
>
> The default value of a HtmlTextWriterTag variable is
> HtmlTextWriterTag.Unknown. This is the value that the variable will have
> if it has not been assigned any value.
>
> --
> Göran Andersson
> _____
> http://www.guffa.com
>

> In VB, "Nothing" is always a shortcut to the default value of a type,
> whether
> the type is a ref type or value type.

So, how about this...

Dim x As Integer = 0

Will the following produce true?

If x = Nothing then
....
End If

Zero is the default value of an Integer type, yet I have explicitly set its
value to zero, so how could I get a true when testing against Nothing?

Try it...
When x = 0, "x = Nothing" evaluates to 'True'
--
David Anton
www.tangiblesoftwaresolutions.com
Instant C#: VB to C# converter
Instant VB: C# to VB converter
C++ to C# Converter: converts C++ to C#
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"Scott M." wrote:

> > In VB, "Nothing" is always a shortcut to the default value of a type,
> > whether
> > the type is a ref type or value type.
>
> So, how about this...
>
> Dim x As Integer = 0
>
> Will the following produce true?
>
> If x = Nothing then
> ....
> End If
>
> Zero is the default value of an Integer type, yet I have explicitly set its
> value to zero, so how could I get a true when testing against Nothing?
>
>
>
>