drag and drop functionality in explorer

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VisualC++

Hi

In the drag and drop functionality, i want to copy a file into a folder in a drive, if the file type and the folder type is similar the drop should occur otherwise the drop should fail.
For eg:
I want to copy a .txt/.java/.cpp file to text/java/cpp folder then only the copy should occur (i.e the folder type and the file extention type should be same)otherwise the copying should fail.
What i mean to say here is when .txt file is copied to text folder the copy should occur, if it is copied to java or cpp folder the copy should not occur.

NOTE: The functionality is happen from one drive to other drive.(i.e one explorer to another explorer)

#pragma region IShellExtInit

// Initialize the drag and drop handler.
IFACEMETHODIMP FileDragDropExt::Initialize(
    LPCITEMIDLIST pidlFolder, LPDATAOBJECT pDataObj, HKEY hKeyProgID)
{
    // Get the directory where the file is dropped to.
    if (!SHGetPathFromIDList(pidlFolder, this->m_szTargetDir))
    {
		return E_FAIL;
    }

    // Get the file(s) being dragged.
    if (NULL == pDataObj)
    {
        return E_INVALIDARG;
    }

    HRESULT hr = E_FAIL;

    FORMATETC fe = { CF_HDROP, NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
    STGMEDIUM stm;

    // The pDataObj pointer contains the objects being acted upon. In this 
    // example, we get an HDROP handle for enumerating the dragged files and 
    // folders.
    if (SUCCEEDED(pDataObj->GetData(&fe, &stm)))
    {
        // Get an HDROP handle.
        HDROP hDrop = static_cast<hdrop>(GlobalLock(stm.hGlobal));
        if (hDrop != NULL)
        {
            // Determine how many files are involved in this operation. This 
            // code sample displays the menu item when only one file (not 
            // directory) is dragged.
            UINT nFiles = DragQueryFile(hDrop, 0xFFFFFFFF, NULL, 0);
            if (nFiles == 1)
            {
                // Get the path of the file.
                if (0 != DragQueryFile(hDrop, 0, m_szSrcFile, ARRAYSIZE(m_szSrcFile)))
                {
                    // The path must not be a directory because hard link is only 
                    // for files, not directories.
                    if (!PathIsDirectory(m_szSrcFile))
                    {
                        hr = S_OK;
                    }

						TCHAR srcfile[210];
			StringCchPrintf(srcfile, ARRAYSIZE(srcfile), 
				L"%s", m_szSrcFile);//contains source path drive upto 8 elements
		
			TCHAR szMessage[210];
			StringCchPrintf(szMessage, ARRAYSIZE(szMessage), L"%s", m_szTargetDir);//contains target path drive upto 8 elements
			wchar_t *dscpath;
			PathStripPath(szMessage);
			PathStripPath(srcfile);
			wchar_t *src=wcstok (srcfile,L".");
			while (src != NULL)
			 {
				 
			dscpath=src;
		   src = wcstok (NULL,L".");
				}
				
		if(!_tcscmp(dscpath,L"txt")&&!_tcsicmp(szMessage,L"text")){

			hr=S_OK;
		}else if(!_tcscmp(dscpath,L"java")&&!_tcsicmp(szMessage,L"java")){

			hr=S_OK;

         }else if(!_tcscmp(dscpath,L"cpp")&&!_tcsicmp(szMessage,L"cpp")){

			hr=S_OK;
		}else{hr=E_FAIL;}
            }
			}
            GlobalUnlock(stm.hGlobal);
        }

        ReleaseStgMedium(&stm);
    }

    // If any value other than S_OK is returned from the method, the menu 
    // item is not displayed.
    return hr;
}

#pragma endregion

This is the code which i implemented.I even have a doubt that is this the correct method i implemented, if there are any other methods to do this functionality please let me know.