In this program we use Dynamic Data Exchange (DDE) with Notepad and Excel. Using Visual C++ a DDE communication server is made to exchange date. If we change the any data in Notepad then automatically data is updated in Excel. By same way we can also use Dynamic Data Exchange with Word and Excel. When possible, it is recommended that you use Automation, not DDE, to communicate with Excel or Word. DDE is a old method or technology. Excel and Word have rich object models that provide functionality through Automation that is not available with DDE. Excel versions 5.o and later , and Word versions 7.0 and later, support Automation. But who are using old version of Excel where Automation is not supported then DDE can be a better solution. I can't explain the program and DDE better than MSDN site so I will provide the reference link where you can learn it .
You can also download the complete project solution compiled in Visual Stdio 2010 with complete source code and power point slide as a user guide form here.