Check if an object is treatable as string/char

29 May 2006 12:14 PM

tommaso.gastaldi

Hi,

does anybody know a speedy analog of IsNumeric() to check for
strings/chars. I would like to check if an Object can be treated as a
string before using a Cstr(), clearly avoiding the time and resource
consuming Try... Catch, which in iterative processing is totally
unacceptable.

-tom

29 May 2006 4:26 PM

Mattias Sjögren

>does anybody know a speedy analog of IsNumeric() to check for
>strings/chars. I would like to check if an Object can be treated as a
>string before using a Cstr(), clearly avoiding the time and resource
>consuming Try... Catch, which in iterative processing is totally
>unacceptable.

I didn't think CStr would throw any exception. It tries to convert
whatever you pass it to a string (by calling ToString if needed). But
if you want to check if something is a string you use

If TypeOf obj Is String Then ...

or possibly the TryCast operator.

Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

29 May 2006 6:31 PM

tommaso.gastaldi

Hi Mattias, thanks for the reply. Cstr() does raise exceptions.

I will explain again my question. Consider the following example:

        Dim AnyObject As Object = New TimeSpan(23)
        Dim AnyObject2 As Object = 34.5D

        For i As Integer = 0 To 5

            Try
                Dim s As String = CStr(AnyObject)
                MsgBox("Conversion1 ok")
            Catch ex As Exception
                MsgBox("Conversion1 failed")
            End Try

            Try
                Dim s As String = CStr(AnyObject2)
                MsgBox("Conversion2 ok")
            Catch ex As Exception
                MsgBox("Conversion2 failed")
            End Try

        Next

I would like to find something that let me recognize when a conversion
to string is possible (the object may be anything) without using:

            Try
            Catch ex As Exception
            End Try

This is possible for instance when one want to recognize if something
is convertible to a number :

            If IsNumeric(AnyObject) Then
                Dim Number As Double = CDbl(AnyObject)
            End If

Note that using IsNumeric instead of any Try Catch is highly advisable
and incomparably faster.

My question : what is the corresponing to check id an obj is
convertible to string:

            If IsConvertibleoString(AnyObject) Then
                Dim Text As String = CStr(AnyObject)
            End If

that is : what could the function IsConvertibleoString(AnyObject as
Object) be (clearly, something fast, not using TryCatch) ??

-tom

Mattias Sjögren ha scritto:

Show quoteHide quote

> >does anybody know a speedy analog of IsNumeric() to check for
> >strings/chars. I would like to check if an Object can be treated as a
> >string before using a Cstr(), clearly avoiding the time and resource
> >consuming Try... Catch, which in iterative processing is totally
> >unacceptable.
>
> I didn't think CStr would throw any exception. It tries to convert
> whatever you pass it to a string (by calling ToString if needed). But
> if you want to check if something is a string you use
>
> If TypeOf obj Is String Then ...
>
> or possibly the TryCast operator.
>
>
> Mattias
>
> --
> Mattias Sjögren [C# MVP] mattias @ mvps.org
> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> Please reply only to the newsgroup.

29 May 2006 7:29 PM

Jay B. Harlow [MVP - Outlook]

Tom,
A conversion to string is *always* possible as you simply need to call
Object.ToString!

Instead of:
Dim s As String = CStr(AnyObject)
Use:
Dim s As String = AnyObject.ToString

However converting to a string is not neccessarily the same as getting the
string representation of an object...

> For i As Integer = 0 To 5

What the fudge! Is a for loop really necessary to show the example??? IMHO I
really don't think so! :-|

Remember that CStr is short hand for CType(..., String). Remember that CType
is Convert type.

In VS2005 (.NET 2.0) you can overload CType on your own types. If a type has
CType overloaded for String, the CStr will use it.

Decimal is "special" in that VB offers a built-in conversion for it.
TimeSpan is not considered as special so the VB compiler looks for an
overloaded CType method to call.

The "problem" with writing a IsConvertibleToString function is knowing which
types have a built-in conversion & which use an overloaded CType operator...

Also CStr behaves differently when given an object parameter verses a
strongly typed parameter. (which IMHO feels like a bug).

For example:

    Public Class Something

    ' VB 2005 syntax
        Public Shared Narrowing Operator CType(ByVal aSomething As
Something) As String
            Return aSomething.ToString()
        End Operator

    End Class

    ' this statement will fail:
        Dim AnyObject As Object = New Something()

    ' this statement will succeed
        Dim AnyObject As New Something()

--
Hope this helps
Jay B. Harlow [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net

<tommaso.gasta***@uniroma1.it> wrote in message

news:1148927517.347799.232750@i39g2000cwa.googlegroups.com...

Hi Mattias, thanks for the reply. Cstr() does raise exceptions.

I will explain again my question. Consider the following example:

        Dim AnyObject As Object = New TimeSpan(23)
        Dim AnyObject2 As Object = 34.5D

        For i As Integer = 0 To 5

            Try
                Dim s As String = CStr(AnyObject)
                MsgBox("Conversion1 ok")
            Catch ex As Exception
                MsgBox("Conversion1 failed")
            End Try

            Try
                Dim s As String = CStr(AnyObject2)
                MsgBox("Conversion2 ok")
            Catch ex As Exception
                MsgBox("Conversion2 failed")
            End Try

        Next

I would like to find something that let me recognize when a conversion
to string is possible (the object may be anything) without using:

            Try
            Catch ex As Exception
            End Try

This is possible for instance when one want to recognize if something
is convertible to a number :

            If IsNumeric(AnyObject) Then
                Dim Number As Double = CDbl(AnyObject)
            End If

Note that using IsNumeric instead of any Try Catch is highly advisable
and incomparably faster.

My question : what is the corresponing to check id an obj is
convertible to string:

            If IsConvertibleoString(AnyObject) Then
                Dim Text As String = CStr(AnyObject)
            End If

that is : what could the function IsConvertibleoString(AnyObject as
Object) be (clearly, something fast, not using TryCatch) ??

-tom

Mattias Sjögren ha scritto:

Show quoteHide quote

> >does anybody know a speedy analog of IsNumeric() to check for
> >strings/chars. I would like to check if an Object can be treated as a
> >string before using a Cstr(), clearly avoiding the time and resource
> >consuming Try... Catch, which in iterative processing is totally
> >unacceptable.
>
> I didn't think CStr would throw any exception. It tries to convert
> whatever you pass it to a string (by calling ToString if needed). But
> if you want to check if something is a string you use
>
> If TypeOf obj Is String Then ...
>
> or possibly the TryCast operator.
>
>
> Mattias
>
> --
> Mattias Sjögren [C# MVP] mattias @ mvps.org
> http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> Please reply only to the newsgroup.

29 May 2006 8:44 PM

tommaso.gastaldi

Jay B. Harlow [MVP - Outlook] ha scritto:

> Tom,
> A conversion to string is *always* possible as you simply need to call
> Object.ToString!
>
> Instead of:
> Dim s As String = CStr(AnyObject)
> Use:
> Dim s As String = AnyObject.ToString
>

Hi Jay, thanks for the contribution. I may be missing something, but I
still feel I did not solve my original problem.

I want something which works for *any* object.

For instance:

        Dim a As Object = New Byte() {}
        Dim s1 As String = CStr(a)
        'a does not have ToString methods

        Dim MyObj As New MyObj
        Dim s2 As String = CStr(MyObj.anything)
        'MyObj.anything does not have ToString methods

and not all have ToString.

> However converting to a string is not neccessarily the same as getting the
> string representation of an object...

that's not important for my problem. I am only concerned about the fact
that Cstr() would work without exception. I dont care about the string
which comes out.

> > For i As Integer = 0 To 5
> What the fudge! Is a for loop really necessary to show the example??? IMHO I
> really don't think so! :-|

Yes. The idea was to give an idea of the intended framework. If there
wasn't some big iteration involved I would just use Try...Catch, as the
fact that it is slow would not be important.
....

> The "problem" with writing a IsConvertibleToString function is knowing which
> types have a built-in conversion & which use an overloaded CType operator....

Function IsConvertibleToString() as Boolean

I would like something which work with any Object and, at the same
time, is not so devastating like Try ... Catch. Just the analog of
IsNumeric().

It is not very clear to me why the language does not readily provide it
(I may just be missing it ! ). This seems a basic need.

I have seen also there is a Converter class. But could not figure out a
way to use it for this problem.

Show quoteHide quote

>
> Also CStr behaves differently when given an object parameter verses a
> strongly typed parameter. (which IMHO feels like a bug).
>
> For example:
>
>     Public Class Something
>
>     ' VB 2005 syntax
>         Public Shared Narrowing Operator CType(ByVal aSomething As
> Something) As String
>             Return aSomething.ToString()
>         End Operator
>
>     End Class
>
>     ' this statement will fail:
>         Dim AnyObject As Object = New Something()
>
>     ' this statement will succeed
>         Dim AnyObject As New Something()
>

mmm ...I am missing your point here (?). (First statement seems
legal).

-tom

Show quoteHide quote

>
> --
> Hope this helps
> Jay B. Harlow [MVP - Outlook]
> .NET Application Architect, Enthusiast, & Evangelist
> T.S. Bradley - http://www.tsbradley.net
>
>
> <tommaso.gasta***@uniroma1.it> wrote in message
> news:1148927517.347799.232750@i39g2000cwa.googlegroups.com...
> Hi Mattias, thanks for the reply. Cstr() does raise exceptions.
>
> I will explain again my question. Consider the following example:
>
>         Dim AnyObject As Object = New TimeSpan(23)
>         Dim AnyObject2 As Object = 34.5D
>
>         For i As Integer = 0 To 5
>
>             Try
>                 Dim s As String = CStr(AnyObject)
>                 MsgBox("Conversion1 ok")
>             Catch ex As Exception
>                 MsgBox("Conversion1 failed")
>             End Try
>
>             Try
>                 Dim s As String = CStr(AnyObject2)
>                 MsgBox("Conversion2 ok")
>             Catch ex As Exception
>                 MsgBox("Conversion2 failed")
>             End Try
>
>         Next
>
>
> I would like to find something that let me recognize when a conversion
> to string is possible (the object may be anything) without using:
>
>             Try
>             Catch ex As Exception
>             End Try
>
> This is possible for instance when one want to recognize if something
> is convertible to a number :
>
>             If IsNumeric(AnyObject) Then
>                 Dim Number As Double = CDbl(AnyObject)
>             End If
>
> Note that using IsNumeric instead of any Try Catch is highly advisable
> and incomparably faster.
>
> My question : what is the corresponing to check id an obj is
> convertible to string:
>
>             If IsConvertibleToString(AnyObject) Then
>                 Dim Text As String = CStr(AnyObject)
>             End If
>
> that is : what could the function IsConvertibleToString(AnyObject as
> Object) be (clearly, something fast, not using TryCatch) ??
>
>
> -tom
>
> Mattias Sjögren ha scritto:
>
> > >does anybody know a speedy analog of IsNumeric() to check for
> > >strings/chars. I would like to check if an Object can be treated as a
> > >string before using a Cstr(), clearly avoiding the time and resource
> > >consuming Try... Catch, which in iterative processing is totally
> > >unacceptable.
> >
> > I didn't think CStr would throw any exception. It tries to convert
> > whatever you pass it to a string (by calling ToString if needed). But
> > if you want to check if something is a string you use
> >
> > If TypeOf obj Is String Then ...
> >
> > or possibly the TryCast operator.
> >
> >
> > Mattias
> >
> > --
> > Mattias Sjögren [C# MVP] mattias @ mvps.org
> > http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> > Please reply only to the newsgroup.

29 May 2006 9:29 PM

Terry

Tom,
I am going to contribute my 2 cents worth here. You say that "and not
all have ToString", which I believe is incorrect. All objects inherit from
System.obect and therefore have a "ToString" method. Now the real question
is what do you mean by "convertable to string"? The developer of an Employee
class may decide to override the ToString method and return the employees
name. But I do not think that this is the same thing as 'convertable to a
string'. I beleive that what you really want to know is whether the object
is in fact a 'value type', but that is just a guess on my part. In addition
to the value types, certainly the string type is convertable. I do not know
if there is an easy way to determine if the object is in fact a value type or
not. Guess the next thing is to find out if my guess is correct or not.

--
Terry

Show quoteHide quote

"tommaso.gasta***@uniroma1.it" wrote:

> Jay B. Harlow [MVP - Outlook] ha scritto:
> > Tom,
> > A conversion to string is *always* possible as you simply need to call
> > Object.ToString!
> >
> > Instead of:
> >                 Dim s As String = CStr(AnyObject)
> > Use:
> >                 Dim s As String = AnyObject.ToString
> >
>
>
> Hi Jay, thanks for the contribution. I may be missing something, but I
> still feel I did not solve my original problem.
>
> I want something which works for *any* object.
>
> For instance:
>
>         Dim a As Object = New Byte() {}
>         Dim s1 As String = CStr(a)
>         'a does not have ToString methods
>
>         Dim MyObj As New MyObj
>         Dim s2 As String = CStr(MyObj.anything)
>         'MyObj.anything does not have ToString methods
>
> and not all have ToString.
>
>
> > However converting to a string is not neccessarily the same as getting the
> > string representation of an object...
>
> that's not important for my problem. I am only concerned about the fact
> that Cstr() would work without exception. I dont care about the string
> which comes out.
>
> > >         For i As Integer = 0 To 5
> > What the fudge! Is a for loop really necessary to show the example??? IMHO I
> > really don't think so! :-|
>
> Yes. The idea was to give an idea of the intended framework. If there
> wasn't some big iteration involved I would just use Try...Catch, as the
> fact that it is slow would not be important.
> ....
> > The "problem" with writing a IsConvertibleToString function is knowing which
> > types have a built-in conversion & which use an overloaded CType operator....
>
> Function IsConvertibleToString() as Boolean
>
> I would like something which work with any Object and, at the same
> time, is not so devastating like Try ... Catch. Just the analog of
> IsNumeric().
>
> It is not very clear to me why the language does not readily provide it
> (I may just be missing it ! ). This seems a basic need.
>
> I have seen also there is a Converter class. But could not figure out a
> way to use it for this problem.
>
> >
> > Also CStr behaves differently when given an object parameter verses a
> > strongly typed parameter. (which IMHO feels like a bug).
> >
> > For example:
> >
> >     Public Class Something
> >
> >     ' VB 2005 syntax
> >         Public Shared Narrowing Operator CType(ByVal aSomething As
> > Something) As String
> >             Return aSomething.ToString()
> >         End Operator
> >
> >     End Class
> >
> >     ' this statement will fail:
> >         Dim AnyObject As Object = New Something()
> >
> >     ' this statement will succeed
> >         Dim AnyObject As New Something()
> >
>
> mmm ...I am missing your point here (?). (First statement seems
> legal).
>
>
> -tom
>
> >
> > --
> > Hope this helps
> > Jay B. Harlow [MVP - Outlook]
> > .NET Application Architect, Enthusiast, & Evangelist
> > T.S. Bradley - http://www.tsbradley.net
> >
> >
> > <tommaso.gasta***@uniroma1.it> wrote in message
> > news:1148927517.347799.232750@i39g2000cwa.googlegroups.com...
> > Hi Mattias, thanks for the reply. Cstr() does raise exceptions.
> >
> > I will explain again my question. Consider the following example:
> >
> >         Dim AnyObject As Object = New TimeSpan(23)
> >         Dim AnyObject2 As Object = 34.5D
> >
> >         For i As Integer = 0 To 5
> >
> >             Try
> >                 Dim s As String = CStr(AnyObject)
> >                 MsgBox("Conversion1 ok")
> >             Catch ex As Exception
> >                 MsgBox("Conversion1 failed")
> >             End Try
> >
> >             Try
> >                 Dim s As String = CStr(AnyObject2)
> >                 MsgBox("Conversion2 ok")
> >             Catch ex As Exception
> >                 MsgBox("Conversion2 failed")
> >             End Try
> >
> >         Next
> >
> >
> > I would like to find something that let me recognize when a conversion
> > to string is possible (the object may be anything) without using:
> >
> >             Try
> >             Catch ex As Exception
> >             End Try
> >
> > This is possible for instance when one want to recognize if something
> > is convertible to a number :
> >
> >             If IsNumeric(AnyObject) Then
> >                 Dim Number As Double = CDbl(AnyObject)
> >             End If
> >
> > Note that using IsNumeric instead of any Try Catch is highly advisable
> > and incomparably faster.
> >
> > My question : what is the corresponing to check id an obj is
> > convertible to string:
> >
> >             If IsConvertibleToString(AnyObject) Then
> >                 Dim Text As String = CStr(AnyObject)
> >             End If
> >
> > that is : what could the function IsConvertibleToString(AnyObject as
> > Object) be (clearly, something fast, not using TryCatch) ??
> >
> >
> > -tom
> >
> > Mattias SjÃ¶gren ha scritto:
> >
> > > >does anybody know a speedy analog of IsNumeric() to check for
> > > >strings/chars. I would like to check if an Object can be treated as a
> > > >string before using a Cstr(), clearly avoiding the time and resource
> > > >consuming Try... Catch, which in iterative processing is totally
> > > >unacceptable.
> > >
> > > I didn't think CStr would throw any exception. It tries to convert
> > > whatever you pass it to a string (by calling ToString if needed). But
> > > if you want to check if something is a string you use
> > >
> > > If TypeOf obj Is String Then ...
> > >
> > > or possibly the TryCast operator.
> > >
> > >
> > > Mattias
> > >
> > > --
> > > Mattias SjÃ¶gren [C# MVP] mattias @ mvps.org
> > > http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> > > Please reply only to the newsgroup.
>
>

29 May 2006 10:17 PM

tommaso.gastaldi

Hi Terry,

OK I got the substance of what You, Jay and Mattias are actually
suggesting, and I think that it solves completely my problem.

You are actually saying that using *always* ToString(), instead of
Cstr(), there is *never* the problem that an exception can be thrown
(unless the Obj has not been instantiated, which can anyway be checked
early by "Is Nothing")

Yes, "if the object is in fact a value type" can be checked by
IsValueType.

    Class MyObj
        Public anything As New Object
    End Class

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click

        Dim MyObj As New MyObj
        MsgBox(MyObj.anything.ToString())
        MsgBox(MyObj.anything.GetType.IsValueType)
    End Sub

Thanky you *VERY* much all. Now I am much more clear on the matter....
you have been very helpful.

-tom

Terry ha scritto:

Show quoteHide quote

> Tom,
>    I am going to contribute my 2 cents worth here. You say that "and not
> all have ToString", which I believe is incorrect. All objects inherit from
> System.obect and therefore have a "ToString" method. Now the real question
> is what do you mean by "convertable to string"? The developer of an Employee
> class may decide to override the ToString method and return the employees
> name. But I do not think that this is the same thing as 'convertable to a
> string'. I beleive that what you really want to know is whether the object
> is in fact a 'value type', but that is just a guess on my part. In addition
> to the value types, certainly the string type is convertable. I do not know
> if there is an easy way to determine if the object is in fact a value type or
> not. Guess the next thing is to find out if my guess is correct or not.
> --
> Terry
>
>
> "tommaso.gasta***@uniroma1.it" wrote:
>
> > Jay B. Harlow [MVP - Outlook] ha scritto:
> > > Tom,
> > > A conversion to string is *always* possible as you simply need to call
> > > Object.ToString!
> > >
> > > Instead of:
> > >                 Dim s As String = CStr(AnyObject)
> > > Use:
> > >                 Dim s As String = AnyObject.ToString
> > >
> >
> >
> > Hi Jay, thanks for the contribution. I may be missing something, but I
> > still feel I did not solve my original problem.
> >
> > I want something which works for *any* object.
> >
> > For instance:
> >
> >         Dim a As Object = New Byte() {}
> >         Dim s1 As String = CStr(a)
> >         'a does not have ToString methods
> >
> >         Dim MyObj As New MyObj
> >         Dim s2 As String = CStr(MyObj.anything)
> >         'MyObj.anything does not have ToString methods
> >
> > and not all have ToString.
> >
> >
> > > However converting to a string is not neccessarily the same as getting the
> > > string representation of an object...
> >
> > that's not important for my problem. I am only concerned about the fact
> > that Cstr() would work without exception. I dont care about the string
> > which comes out.
> >
> > > >         For i As Integer = 0 To 5
> > > What the fudge! Is a for loop really necessary to show the example??? IMHO I
> > > really don't think so! :-|
> >
> > Yes. The idea was to give an idea of the intended framework. If there
> > wasn't some big iteration involved I would just use Try...Catch, as the
> > fact that it is slow would not be important.
> > ....
> > > The "problem" with writing a IsConvertibleToString function is knowing which
> > > types have a built-in conversion & which use an overloaded CType operator....
> >
> > Function IsConvertibleToString() as Boolean
> >
> > I would like something which work with any Object and, at the same
> > time, is not so devastating like Try ... Catch. Just the analog of
> > IsNumeric().
> >
> > It is not very clear to me why the language does not readily provide it
> > (I may just be missing it ! ). This seems a basic need.
> >
> > I have seen also there is a Converter class. But could not figure out a
> > way to use it for this problem.
> >
> > >
> > > Also CStr behaves differently when given an object parameter verses a
> > > strongly typed parameter. (which IMHO feels like a bug).
> > >
> > > For example:
> > >
> > >     Public Class Something
> > >
> > >     ' VB 2005 syntax
> > >         Public Shared Narrowing Operator CType(ByVal aSomething As
> > > Something) As String
> > >             Return aSomething.ToString()
> > >         End Operator
> > >
> > >     End Class
> > >
> > >     ' this statement will fail:
> > >         Dim AnyObject As Object = New Something()
> > >
> > >     ' this statement will succeed
> > >         Dim AnyObject As New Something()
> > >
> >
> > mmm ...I am missing your point here (?). (First statement seems
> > legal).
> >
> >
> > -tom
> >
> > >
> > > --
> > > Hope this helps
> > > Jay B. Harlow [MVP - Outlook]
> > > .NET Application Architect, Enthusiast, & Evangelist
> > > T.S. Bradley - http://www.tsbradley.net
> > >
> > >
> > > <tommaso.gasta***@uniroma1.it> wrote in message
> > > news:1148927517.347799.232750@i39g2000cwa.googlegroups.com...
> > > Hi Mattias, thanks for the reply. Cstr() does raise exceptions.
> > >
> > > I will explain again my question. Consider the following example:
> > >
> > >         Dim AnyObject As Object = New TimeSpan(23)
> > >         Dim AnyObject2 As Object = 34.5D
> > >
> > >         For i As Integer = 0 To 5
> > >
> > >             Try
> > >                 Dim s As String = CStr(AnyObject)
> > >                 MsgBox("Conversion1 ok")
> > >             Catch ex As Exception
> > >                 MsgBox("Conversion1 failed")
> > >             End Try
> > >
> > >             Try
> > >                 Dim s As String = CStr(AnyObject2)
> > >                 MsgBox("Conversion2 ok")
> > >             Catch ex As Exception
> > >                 MsgBox("Conversion2 failed")
> > >             End Try
> > >
> > >         Next
> > >
> > >
> > > I would like to find something that let me recognize when a conversion
> > > to string is possible (the object may be anything) without using:
> > >
> > >             Try
> > >             Catch ex As Exception
> > >             End Try
> > >
> > > This is possible for instance when one want to recognize if something
> > > is convertible to a number :
> > >
> > >             If IsNumeric(AnyObject) Then
> > >                 Dim Number As Double = CDbl(AnyObject)
> > >             End If
> > >
> > > Note that using IsNumeric instead of any Try Catch is highly advisable
> > > and incomparably faster.
> > >
> > > My question : what is the corresponing to check id an obj is
> > > convertible to string:
> > >
> > >             If IsConvertibleToString(AnyObject) Then
> > >                 Dim Text As String = CStr(AnyObject)
> > >             End If
> > >
> > > that is : what could the function IsConvertibleToString(AnyObject as
> > > Object) be (clearly, something fast, not using TryCatch) ??
> > >
> > >
> > > -tom
> > >
> > > Mattias Sjögren ha scritto:
> > >
> > > > >does anybody know a speedy analog of IsNumeric() to check for
> > > > >strings/chars. I would like to check if an Object can be treated as a
> > > > >string before using a Cstr(), clearly avoiding the time and resource
> > > > >consuming Try... Catch, which in iterative processing is totally
> > > > >unacceptable.
> > > >
> > > > I didn't think CStr would throw any exception. It tries to convert
> > > > whatever you pass it to a string (by calling ToString if needed). But
> > > > if you want to check if something is a string you use
> > > >
> > > > If TypeOf obj Is String Then ...
> > > >
> > > > or possibly the TryCast operator.
> > > >
> > > >
> > > > Mattias
> > > >
> > > > --
> > > > Mattias Sjögren [C# MVP] mattias @ mvps.org
> > > > http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
> > > > Please reply only to the newsgroup.
> >
> >