How to read/write Excel file from VC++...

Edited text of question

Perhaps you write a macro in VBA which exports the table into a file and then you fetch
that file ... I don't think that there is another way than the way you tried.
Good luck :)

If you just want to write out a data file that Excel can read, then write out a CSV file.  Excel can export this, and you can write this very fast from a C program (e.g. using the file APIs).

If you to write a true Excel file (e.g. you want formatting and macros etc. in the spreadsheet) get the Excel SDK which is kind of a book and disk (there's a reference to it on Microsoft Developer's Network).  Even an old SDK will work as new Excels read old formats.  

The other alternatives are to use the Formula 1 Spreadsheet control (OCX) which I believe can write Excel files, or use the OLE Structured format of that the new versions of Excel use (this is also documented on MSDN, but I can't find the article at the moment - I've seen it before)

Thanks for your answer.

Perhaps my question is not clear.
What I want to do is: get/put cell value
from/into a real excel file(.xls) very fast
from a VC++ program.

What I have done is:
1) Use VB to wrote a ActiveX control which use
   following lines to get/set cell value in its methods:
   ...
   GetCellData = xlsheet.Cells(i,j).Value
   ...
   xlsheet.Cells(i,j).Value = value_to_set
   ...
2) Use IDispatch wrapper class to wrap this ActiveX Control
   in my VC++ project.

This approach can work, but performacne is not good.
By the way, my PC is Pentium_90MHz/96M memory.

Thanks again for your respones.

The only ways i see are:
a) like answer2000 proposed, to purchase a SDK to access excels data files directly
b) write the ActiveX control wrapper with Visual C++ directly
    ( i think this should work with 'Insert|Component...|Ole Controls ...')
    Even if this works, i think the performance gain will be if any really small.
c) To contact microsoft directly and ask them for support - sometimes they can be really help-
     ful. Perhaps you can get a documentation on the file format with complete specifications
     (specific for Excel) - or even a doc of the dll's which are used by excel itself.
d) Perhaps you can get an ODBC driver to access the excel sheets
 

I have done searching and reading of string and number in Excel file with P200, 128MB and with speed is quite slow too.
The other difference is i use a dll instead.

Is ocx faster than dll?

What dll are you talking of? I think it is possible to access the whole Excel application itself
as an 'OLE control' - I am not sure though. This way *could* be quite fast, but i don't know,
i've never tried it (as i don't have excel).
Could you explain any further what you mean with
  >> Use VB to wrote a ActiveX control which use ...
Do you mean VBA or did you write an OCX wrapper class using VB?

Thanks for your answer.
By the way I wrote that OCX by creating a "ActiveX Control"
project and using "Make ...ocx" menu item of File.