find all open Excel workbooks

Question

I\'m trying to get a list of all currently open Excel workbooks, so that the user can select which one of them to get some data from.

I tried this:

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Answer 1

This code was put together using the resource (Link) in the last comment and the code you supplied. This should pull in all open workbook names.

using Excel = Microsoft.Office.Interop.Excel;        

[DllImport("User32")]
public static extern int GetClassName(
    int hWnd, StringBuilder lpClassName, int nMaxCount);


// Callback passed to EnumChildWindows to find any window with the
// registered classname "paneClassDC" - this is the class name of
// PowerPoint's accessible document window.
public bool EnumChildProc(int hwnd, ref int lParam)
{
    StringBuilder windowClass = new StringBuilder(128);
    GetClassName(hwnd, windowClass, 128);
    s += windowClass.ToString() + "\n";
    if (windowClass.ToString() == "EXCEL7")
    {
        lParam = hwnd;
    }
    return true;
}

public delegate bool EnumChildCallback(int hwnd, ref int lParam);


[DllImport("User32")]
public static extern bool EnumChildWindows(
    int hWndParent, EnumChildCallback lpEnumFunc, ref int lParam);


[DllImport("User32")]
public static extern int FindWindowEx(
    int hwndParent, int hwndChildAfter, string lpszClass,
    int missing);


// AccessibleObjectFromWindow gets the IDispatch pointer of an object
// that supports IAccessible, which allows us to get to the native OM.
[DllImport("Oleacc.dll")]
private static extern int AccessibleObjectFromWindow(
    int hwnd, uint dwObjectID,
    byte[] riid,
    ref Excel.Window ptr);


// Get the window handle for a running instance of PowerPoint.
internal List GetAccessibleObject()
{

    List workbookNames = new List();
    try
    {
        // Walk the children of the desktop to find PowerPoint’s main
        // window.
        int hwnd = FindWindowEx(0, 0, "XLMAIN", 0);
        while(hwnd != 0)
        if (hwnd != 0)
        {
            // Walk the children of this window to see if any are
            // IAccessible.
            int hWndChild = 0;
            EnumChildCallback cb =
                new EnumChildCallback(EnumChildProc);
            EnumChildWindows(hwnd, cb, ref hWndChild);


            if (hWndChild != 0)
            {
                // OBJID_NATIVEOM gets us a pointer to the native 
                // object model.
                uint OBJID_NATIVEOM = 0xFFFFFFF0;
                Guid IID_IDispatch =
                    new Guid("{00020400-0000-0000-C000-000000000046}");
                Excel.Window ptr = null;
                int hr = AccessibleObjectFromWindow(
                    hWndChild, OBJID_NATIVEOM,
                    IID_IDispatch.ToByteArray(), ref ptr);
                if (hr >= 0)
                {
                    Excel.Application eApp = ptr.Application;
                    if (eApp != null)
                    {
                        foreach (Excel.Workbook wb in eApp.Workbooks)
                        {
                            workbookNames.Add(wb.FullName);
                        }
                        Marshal.ReleaseComObject(eApp);
                        GC.WaitForPendingFinalizers();
                        GC.Collect();
                    }
                }

                hwnd = FindWindowEx(0, hwnd, "XLMAIN", 0);
            }
        }
    }
    catch (Exception ex)
    {
        Debug.WriteLine(ex.ToString());
    }
    return workbookNames;
}