title: Excel calling a function of a C++ program
body: <ol>
  <li>I have a C++ program, program.exe that has a function doSomething()</li>
  <li>But instead of having a logic in program.exe to call doSomething(), I need excel to be the frontend to decide when to call this doSomething()  - based on some changes in a particular cell</li>
  <li>XML/CSV IO is out because the decision making is in realtime, low latency</li>
  <li>So how do I go about interfacing excel with program.exe in order for excel to invoke doSomething()</li>
  </ol>
  
  <p>I do hope someone could point me in a direction. Im using QT 4.8.5 to develop the c++ project.
  I've been reading , but COM models are very new to me.. Do i write a COM model? DLL? </p>
  
  <p>how would the COM/DLL "know" that excel has invoked it and thus provide some sort of "acknowledgement" and in turn invoke the doSomething() in program.exe?</p>