Dear all,

I have the excel file which is opened and run the dllfunction which will
manipulate this excel file.
How can I write in dllfunction so that it can work the excel file which has
been opened??

Let me mention more clearly.
xlapp=new excel.applicationclass() // Actually test.xls has been opened.
xlworkbook=xlapp.WorkBooks.open("test.xls",....); // open again, it will
make two test.xls excel screen. How to eliminate this and working on the
existing opened excel file??
.............................
I want as below.

if (There is instance of excel exists)
{
set xlApp to be excel instance
set xlWorkBook=xlApp.ActiveWorkBook;
}
else
{
create new excel instance and set to xlApp.
set xlWorkBook=xlApp.Workbooks.Open(...........)
}