Eclipse indexing not working

Question

I am using CDT in Eclipse 3.5.2 Galileo in Ubuntu.

My eclipse\'s indexer doesn\'t work at times. By that I mean when I ctrl click a function it says

Answer 1

In my case nothing has worked and at last I did the following:

 1) Close the project
 2) Delete the project(do not check from disk option)
 3) create new project with existing code(use the deleted project path)
 4) Successfully indexed my c++ code