title: How to start modification with big projects
body: <p><br/>
  I have to do enhancements to an existing C++ project with above 100k lines of code.
  <br/>
  My question is How and where to start with such projects ?
  <br>The problem increases further if the code is not well documented.
  Are there any automated tools for studying code flow with large projects?<br></p>
  
  <p>Thanx, </p>