Including header files style - C++

Question

I have a project which has the following directory structure.

root
--include
----module1
----module2
--src
----module1
----module2

So a file say foo.cpp in src/module1 has to include like,

#include "../../include/module1/foo.hpp"

This looks messy and tough to write. I found writing include like

#include <module1/foo.h>

and providing include file search path to root/include when compiling looks neat. However, I am not sure that this style has got any drawbacks.

Which one do you prefer and why? Also do you see any problems in organizing files in the above way?

Answer 1

#include "../../include/module1/foo.hpp"

Specifying paths should be avoided as much as possible. Compilers provide you with a cleaner alternative to achieve the same. Further, a clean design should see to it that you do not need to juggle relative paths for including headers.

A better idea of which one to use (including whether to use quotes or the angle-brackets) can be had from the standard.

From my copy of the C++ draft:

16.2 Source file inclusion

2 A preprocessing directive of the form

#include <h-char-sequence> new-line`

searches a sequence of implementation-defined places for a header identified uniquely by the specified sequence between the < and > delimiters, and causes the replacement of that directive by the entire contents of the header. How the places are specified or the header identified is implementation-defined.

3 A preprocessing directive of the form

# include "q-char-sequence" new-line 

causes the replacement of that directive by the entire contents of the source file identified by the specified sequence between the " delimiters. The named source file is searched for in an implementation-defined manner. If this search is not supported, or if the search fails, the directive is reprocessed as if it read

#include <h-char-sequence> new-line`

with the identical contained sequence (including > characters, if any) from the original directive.

7 Although an implementation may provide a mechanism for making arbitrary source files available to the < > search, in general programmers should use the < > form for headers provided with the implementation, and the " " form for sources outside the control of the implementation.