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c++cgccincludeg++

How to tell where a header file is included from?

How can I tell where g++ was able to find an include file? Basically if I

#include <foo.h>

g++ will scan the search path, using any include options to add or alter the path. But, at the end of days, is there a way I can tell the absolute path of foo.h that g++ chose to compile? Especially relevant if there is more than one foo.h in the myriad of search paths.

Short of a way of accomplishing that... is there a way to get g++ to tell me what its final search path is after including defaults and all include options?

Solution

  • This will give make dependencies which list absolute paths of include files:

    gcc  -M showtime.c

    If you don't want the system includes (i.e. #include <something.h>) then use:

    gcc  -MM showtime.c