C# Signature:

[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);

User-Defined Types:

EnumWindowsProc

Notes:

Callback EnumWindowsProc should return true to continue enumerating or false to stop.

Tips & Tricks:

The corresponding unmanaged return type is a 4-byte Win32 'BOOL', so mark the method with the MarshalAsAttribute(UnmanagedType.Bool).

Great sample using managed code and a delegate type for the call back from MSDN:

http://msdn2.microsoft.com/en-us/library/d186xcf0(VS.71).aspx

SAMPLE CODE!!

using System.Runtime.InteropServices;

public delegate bool CallBackPtr(int hwnd, int lParam);

public class EnumReport
{
    [DllImport("user32.dll")]
    public static extern int EnumWindows(CallBackPtr callPtr, int lPar);
    public static bool Report(int hwnd, int lParam)
    {
        Console.WriteLine("Window handle is "+hwnd);
        return true;
    }
}
static void Main()
{
    CallBackPtr callBackPtr = new CallBackPtr(EnumReport.Report);
    EnumReport.EnumWindows(callBackPtr, 0);
}

Alternative Managed API:

The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides a static

method ManagedWinapi.SystemWindow.FilterToplevelWindows().

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