Shell32 - Fetching multiple Item with IEnumIDList.Next()

Not really a problem but rather a question (I guess?) Regarding the IEnumIDList interface and his .Next() method.

Usually I use it like this :

while (enumIdList.Next(1, out IntPtr pIdlOut, out _) == HRESULT.S_OK) // S_OK and not .Successed
{
// do something
}

The problem is that if I want to fetch more than 1 item pIdlOut must be an array (IntPtr[]), right ? I can’t do :

if (enumIdList.Next(5, out IntPtr pIdlOut, out _) == HRESULT.S_OK)
{
// pIdlOut is the last feteched pidl
// fetching more than 5 items throw an error (System.ExecutionEngineException)
}

Changing the .Next() Method to

HRESULT Next(uint celt, [MarshalAs(UnmanagedType.LPArray), Out] out IntPtr[] rgelt, out uint pceltFetched);

or

HRESULT Next(uint celt, [MarshalAs(UnmanagedType.LPArray), In] in IntPtr[] rgelt, out uint pceltFetched);

Same issue.

From MSDN :

rgelt Type: LPITEMIDLIST* The address of a pointer to an array of ITEMIDLIST pointers

The implementation must allocate these item identifiers using CoTaskMemAlloc

I guess I need to pass an already allocated array, but how ?

[dahall]

foreach (var pidl in enumIdList.Enumerate(fv.ItemCount(SVGIO.SVGIO_ALLVIEW)))
{
    using (pidl)
    {
        // Do something with pidl;
    }
}

[dahall]

I just changed the definition in Vanara.PInvoke.Shell32 to the one I thought was the correct definition and tested it. It now works as it should. I also added an extension method for IEnumIDList instances called Enumerate that will take a parameter to determine retrieval size. The default value for that parameter is set to 1. It can be used like:

// Enumerate all PIDLs in enumIdList requesting 20 at a time
IEnumerable<PIDL> pidls = enumIdList.Enumerate(20);

// Enumerate all PIDLs in enumIdList requesting 1 at a time
IEnumerable<PIDL> pidls2 = enumIdList.Enumerate();