Search
Module:
Directory

   Desktop Functions:

   Smart Device Functions:


Show Recent Changes
Subscribe (RSS)
Misc. Pages
Comments
FAQ
Helpful Tools
Playground
Suggested Reading
Website TODO List
Download Visual Studio Add-In

GetClassLong (user32)
 
.
Summary
Summary

C# Signature:

public static IntPtr GetClassLongPtr(HandleRef hWnd, int nIndex)
{
    if (IntPtr.Size > 4)
        return GetClassLongPtr64(hWnd, nIndex);
    else
        return new IntPtr(GetClassLongPtr32(hWnd, nIndex));
}

[DllImport("user32.dll", EntryPoint="GetClassLong")]
public static extern uint GetClassLongPtr32(HandleRef hWnd, int nIndex);

[DllImport("user32.dll", EntryPoint="GetClassLongPtr")]
public static extern IntPtr GetClassLongPtr64(HandleRef hWnd, int nIndex);

VB.NET Signature:

Public Shared Function GetClassLongPtr(ByVal hWnd As HandleRef, ByVal nIndex As Integer) As IntPtr
    If IntPtr.Size > 4 Then
        Return GetClassLongPtr64(hWnd, nIndex)
    Else
        Return New IntPtr(GetClassLongPtr32(hWnd, nIndex))
    End If
[Obsolete("This method will crash on 64-bit operating systems. Use GetClassLongPtr instead"),
DllImport("user32.dll")]
static extern uint GetClassLong(IntPtr hWnd, int nIndex);

VB.NET Signature

<DllImport("user32.dll", EntryPoint:="GetClassLongA", SetLastError:=True, CharSet:=CharSet.Ansi)> _
Public Function GetClassLong(hWnd as IntPtr, <MarshalAs(UnmanagedType.I4)>nIndex as ClassLongFlags) as Integer

End Function

<DllImport("user32.dll", EntryPoint:="GetClassLong")> _
Public Shared Function GetClassLongPtr32(ByVal hWnd As HandleRef, <MarshalAs(UnmanagedType.I4)>nIndex As ClassLongFlags) As UInteger
End Function

<DllImport("user32.dll", EntryPoint:="GetClassLongPtr")> _
Public Shared Function GetClassLongPtr64(ByVal hWnd As HandleRef, <MarshalAs(UnmanagedType.I4)>nIndex As ClassLongFlags) As IntPtr
End Function

VB Signature:

Public Declare Function GetClassLongPtr Lib "user32"

VB Signature

Public Declare Function GetClassLong Lib "user32" Alias "GetClassLongA" _
        (ByVal hWnd As Long, _
         ByVal nIndex As ClassLongFlags) As Long

         ByVal nIndex As Long) As Long

User-Defined Types:

ClassLongFlags

None.

Notes:

GetClassLongPtr is 64-bit safe, GetClassLong is not.

Because GetClassLongPtr is not available on older 32-bit operating systems, a special wrapper function is required. The MSDN documentation specifies that GetClassLongPtr is supported on older 32-bit operating systems such as Windows 95. However, the Win32 API actually uses a macro to change GetClassLongPtr to GetClassLong on these older systems.

Testing the size of the IntPtr is the easiest way to determine if the platform is 64-bit.

This declaration will crash on 64-bit operating systems.

"GetClassLong" is obsolete and "GetClassLongPtr" should be used instead.

Tips & Tricks:

Please add some!

Sample Code:

Please add some!

Alternative Managed API:

Do you know one? Please contribute it!

Documentation
Documentation

Please edit this page!

Do you have...

  • helpful tips or sample code to share for using this API in managed code?
  • corrections to the existing content?
  • variations of the signature you want to share?
  • additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).

 
Access PInvoke.net directly from VS:
Terms of Use
Edit This Page
Find References
Show Printable Version
Revisions