Eclipse compiler includes a subdir path

I need to add multiple included directories to my project properties in Eclipse. I am using Eclipse 4.3.2 with the GCC C compiler. Header directories consist of several subdirectories with new header files.

How do I tell the compiler to also look in subdirectories at compile time?

I am currently moving to

Project > Properties > tab C/C++ Build > settings > Tool settings > GCC C compiler > includes

      

        
        
        
      

    

There I add:

"${workspace_loc:/${ProjName}/Source/include}"
"${workspace_loc:/${ProjName}/Source/include/internal}"
"${workspace_loc:/${ProjName}/Source/include/internal/services}"

      

        
        
        
      

    

At this point, I added all the subdirectories manually so that each subdirectory gets its own string. But I'm guessing there is a simple command to let the compiler know what is in the subdirectories too? I'm only looking for a simple command to get rid of all these fixed paths.

Any suggestions are greatly appreciated. Thank.