What is syntax to test if Object is a String?

Joe Fallon

I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)
--
Joe Fallon

Nov 20 '05 #1

Subscribe Reply

49291

Herfried K. Wagner [MVP]

* "Joe Fallon" <jf******@nospa mtwcny.rr.com> scripsit:

I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)

\\\
Dim o As Object = 2
Dim p As Object = "Hello"
Dim q As Object = Me
MsgBox(TypeOf o Is String)
MsgBox(TypeOf p Is String)
MsgBox(TypeOf q Is String)
///

--
Herfried K. Wagner
MVP · VB Classic, VB.NET
<http://www.mvps.org/dotnet>

Nov 20 '05 #2

Joe Fallon

Always figure it out 5 seconds after posting!! <g>

If Object.GetType Is GetType(String) Then

--
Joe Fallon

"Joe Fallon" <jf******@nospa mtwcny.rr.com> wrote in message
news:%2******** *******@TK2MSFT NGP10.phx.gbl.. .

I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)
--
Joe Fallon

Nov 20 '05 #3

_Andy_

On Wed, 22 Oct 2003 16:39:56 -0400, "Joe Fallon"
<jf******@nospa mtwcny.rr.com> wrote:

I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)

If TypeOf something Is String Then
....

Nov 20 '05 #4

Joe Fallon

If TypeOf Object Is String Then

Perfect!
Thanks!
--
Joe Fallon

"Herfried K. Wagner [MVP]" <hi************ ***@gmx.at> wrote in message
news:bn******** ****@ID-208219.news.uni-berlin.de...

* "Joe Fallon" <jf******@nospa mtwcny.rr.com> scripsit:
I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)

\\\
Dim o As Object = 2
Dim p As Object = "Hello"
Dim q As Object = Me
MsgBox(TypeOf o Is String)
MsgBox(TypeOf p Is String)
MsgBox(TypeOf q Is String)
///

--
Herfried K. Wagner
MVP · VB Classic, VB.NET
<http://www.mvps.org/dotnet>

Nov 20 '05 #5

Armin Zingler

"Joe Fallon" <jf******@nospa mtwcny.rr.com> schrieb

I would like to know the syntax to check that an Object is a
String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)

You didn't supply details, so I guess the answer is

If typeof o is string then

end if
--
Armin

Nov 20 '05 #6

Jay B. Harlow [MVP - Outlook]

Joe,
I would recommend what Herfried showed:

If Typeof obj Is String Then

The difference being is that TypeOf will succeed for derived types, where as
GetType matches the type exactly. For String not much of a difference, for
other types that you derive from, such as Control it can be a world of
difference.

Dim c As Control
c = New TextBox

If TypeOf c Is Control Then
' True : TextBox inherits from Control
End If

If c.GetType() Is GetType(Control ) Then
Else
' False : c is actually a TextBox
End If

Hope this helps
Jay

"Joe Fallon" <jf******@nospa mtwcny.rr.com> wrote in message
news:ek******** *****@TK2MSFTNG P10.phx.gbl...

Always figure it out 5 seconds after posting!! <g>

If Object.GetType Is GetType(String) Then

--
Joe Fallon

"Joe Fallon" <jf******@nospa mtwcny.rr.com> wrote in message
news:%2******** *******@TK2MSFT NGP10.phx.gbl.. .
I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)
--
Joe Fallon

Nov 20 '05 #7

Joe Fallon

Jay,
Thanks.
I did switch my code to:
If Typeof obj Is String Then

because it seemed "more elegant".

But now I know it is also "safer".

Good advice. Appreciate it!
--
Joe Fallon
"Jay B. Harlow [MVP - Outlook]" <Ja********@ema il.msn.com> wrote in message
news:%2******** ********@TK2MSF TNGP12.phx.gbl. ..

Joe,
I would recommend what Herfried showed:

If Typeof obj Is String Then

The difference being is that TypeOf will succeed for derived types, where as GetType matches the type exactly. For String not much of a difference, for
other types that you derive from, such as Control it can be a world of
difference.

Dim c As Control
c = New TextBox

If TypeOf c Is Control Then
' True : TextBox inherits from Control
End If

If c.GetType() Is GetType(Control ) Then
Else
' False : c is actually a TextBox
End If

Hope this helps
Jay

"Joe Fallon" <jf******@nospa mtwcny.rr.com> wrote in message
news:ek******** *****@TK2MSFTNG P10.phx.gbl...
Always figure it out 5 seconds after posting!! <g>

If Object.GetType Is GetType(String) Then

--
Joe Fallon

"Joe Fallon" <jf******@nospa mtwcny.rr.com> wrote in message
news:%2******** *******@TK2MSFT NGP10.phx.gbl.. .
I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)
--
Joe Fallon

Nov 20 '05 #8

Gary Owsiany

"Joe Fallon" <jf******@nospa mtwcny.rr.com> wrote in message
news:%2******** *******@TK2MSFT NGP10.phx.gbl.. .

I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)
--
Joe Fallon

In Object-oriented programming, type-checking is considered a "poor
practice". Depending upon what you are trying to accomplish, consider using
polymorphism to accomplish your task. Then, instead of "testing" to see
what object you are using, the object itself will know the correct response
for the message you are sending to it.

Gary O.

Nov 20 '05 #9

Joe Fallon

I have an argument that takes an Object.
But in the special case when the Object is a String I need to do something
extra.

So this is perfect for my needs:
If TypeOf something Is String Then
--
Joe Fallon

"Gary Owsiany" <ga*****@swbell .net> wrote in message
news:Qp******** ********@newssv r24.news.prodig y.com...

"Joe Fallon" <jf******@nospa mtwcny.rr.com> wrote in message
news:%2******** *******@TK2MSFT NGP10.phx.gbl.. .
I would like to know the syntax to check that an Object is a String.

If it was a number test I might use IsNumeric.
But there is no function: IsString (is there?)
--
Joe Fallon

In Object-oriented programming, type-checking is considered a "poor
practice". Depending upon what you are trying to accomplish, consider

using polymorphism to accomplish your task. Then, instead of "testing" to see
what object you are using, the object itself will know the correct response for the message you are sending to it.

Gary O.

Nov 20 '05 #10

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