GetClassName

[Kartic]

Hi,

Declare Ansi Function GetClassName Lib "user32" Alias "GetClassNameA"
( ByVal hWnd As IntPtr, ByVal lpClassName As System.Text.StringBuilder,
ByVal nMaxCount As Int32) As Int32

I am trying go use GetClassName API to get the class name, but I don't know
how to pass IntPtr.
I'll appreciate your help.

Thanks in advance.
Kartic

[Shawn D Shelton]

Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA"
(ByVal hwnd As Int32, ByVal lpClassName As String, ByVal nMaxCount As
Int32) As Int32
afaik there is no such thing as a IntPtr in .net. You will have to pass
it as the type of variable that is required by the api. In this case it
is an int32.

Kartic wrote:

Hi,

Declare Ansi Function GetClassName Lib "user32" Alias "GetClassNameA"
( ByVal hWnd As IntPtr, ByVal lpClassName As System.Text.StringBuilder,
ByVal nMaxCount As Int32) As Int32

I am trying go use GetClassName API to get the class name, but I don't know
how to pass IntPtr.
I'll appreciate your help.

Thanks in advance.
Kartic

[Tom Shelton]

In article <OF**************@TK2MSFTNGP10.phx.gbl>, Kartic wrote:

Hi,

Declare Ansi Function GetClassName Lib "user32" Alias "GetClassNameA"
( ByVal hWnd As IntPtr, ByVal lpClassName As System.Text.StringBuilder,
ByVal nMaxCount As Int32) As Int32

I would delcare this more like:

Declare Auto Function GetClassName Lib "user32" _
(ByVal hWnd As IntPtr, _
ByVal lpClassName As System.Text.StringBuilder, _
ByVal nMaxCount As Integer) As Integer
This way you let the runtime call the appropriate function based on the
platfrom - which can make a difference on NT systems, since you cut out
a lot of Ansi->unicode, Unicode -> Ansi conversions.
I am trying go use GetClassName API to get the class name, but I don't know
how to pass IntPtr.
I'll appreciate your help.

Well, the IntPtr is the handle of the window your trying to get the
class name of... So, if your trying to get the class name of the
current form:

Dim className As New StringBuidler(255)

GetClassName(Me.Handle, className, className.Capacity)

Return className.ToString()

--
Tom Shelton
MVP [Visual Basic]

[Tom Shelton]

In article <u#**************@TK2MSFTNGP09.phx.gbl>, Shawn D Shelton wrote:

Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA"
(ByVal hwnd As Int32, ByVal lpClassName As String, ByVal nMaxCount As
Int32) As Int32

Acutally, it would probably be better to drop the alias and use the Auto
modifier:

Private Declare Auto Function GetClassName Lib "user32" _
(ByVal hWnd As IntPtr, _
ByVal lpClassName As System.Text.StringBuilder, _
ByVal nMaxCount As Integer) As Integer

Also, notice I changed the string to stringbuilder. You should never
pass strings that are intended to be modified by the caller. It equates
to a large amount of overhead for the marshaller. It is preferable to
use System.Text.StringBuilder because it is a mutable buffer.

afaik there is no such thing as a IntPtr in .net. You will have to pass
it as the type of variable that is required by the api. In this case it
is an int32.

System.IntPtr. It should be used for all handle types - including
hWnds - when doing P/Invoke.

--
Tom Shelton
MVP [Visual Basic]

[Herfried K. Wagner [MVP]]

* "Kartic" <kg****@csystemssoftware.com> scripsit:

Declare Ansi Function GetClassName Lib "user32" Alias "GetClassNameA"
( ByVal hWnd As IntPtr, ByVal lpClassName As System.Text.StringBuilder,
ByVal nMaxCount As Int32) As Int32
Why do you declare the function as 'Ansi'? Declare it as 'Auto' and
remove the alias ('Alias...').
I am trying go use GetClassName API to get the class name, but I don't know
how to pass IntPtr.

\\\
n = GetClassName(Me.Handle, ..., ...)
///

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