C# Signature:
public static IntPtr SetClassLong(HandleRef hWnd, int nIndex, IntPtr dwNewLong)
{
if (IntPtr.Size > 4)
return SetClassLongPtr64(hWnd, nIndex, dwNewLong);
else
return new IntPtr(SetClassLongPtr32(hWnd, nIndex, unchecked((uint)dwNewLong.ToInt32())));
}
[DllImport("user32.dll", EntryPoint="SetClassLong")]
public static extern uint SetClassLongPtr32(HandleRef hWnd, int nIndex, uint dwNewLong);
[DllImport("user32.dll", EntryPoint="SetClassLongPtr")]
public static extern IntPtr SetClassLongPtr64(HandleRef hWnd, int nIndex, IntPtr dwNewLong);
VB.NET Signature:
<DllImport("user32.dll", EntryPoint:="SetClassLongPtrA", SetLastError:=True, CharSet:=CharSet.Ansi)> _
Public Function SetClassLongPtr(hWnd as IntPtr, <MarshalAs(UnmanagedType.I4)>nIndex as ClassLongFlags, newLong as Integer) as Integer
End Function
VB Signature:
Public Declare Function SetClassLongPtr Lib "user32" Alias "SetClassLongPtrA" _
(ByVal hWnd As Long, _
ByVal nIndex As ClassLongFlags, _
ByVal dwNewLong As Long) As Long
User-Defined Types:
Notes:
SetClassLongPtr is 64-bit safe, SetClassLong is not.
Because SetClassLongPtr is not available on older 32-bit operating systems, a special wrapper function is required. The MSDN documentation specifies that SetClassLongPtr is supported on older 32-bit operating systems such as Windows 95. However, the Win32 API actually uses a macro to change SetClassLongPtr to SetClassLong on these older systems.
Testing the size of the IntPtr is the easiest way to determine if the platform is 64-bit.
Tips & Tricks:
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Sample Code:
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Alternative Managed API:
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