Question

I’m a C Newb

I write lots of code in dynamic languages (javascript, python, haskell, etc.), but I’m now learning C for graduate school and I have no idea what I’m doing.

The Problem

Originally I was building all my source in one directory using a makefile, which has worked rather well. However, my project is growing and I would like to split the source into multiple directories (unit tests, utils, core, etc.). For example, my directory tree might look like the following:

. |-- src |   |-- foo.c |   |-- foo.h |   `-- main.c `-- test     `-- test_foo.c 

test/test_foo.c uses both src/foo.c and src/foo.h. Using makefiles, what is the best/standard way to build this? Preferably, there would be one rule for building the project and one for building the tests.

Note

I know that there are other ways of doing this, including autoconf and other automatic solutions. However, I would like to understand what is happening and be able to write the makefiles from scratch despite its possible impracticality.

Any guidance or tips would be appreciated. Thanks!

[Edit]

So the three solutions given so far are as follows:

• Place globally used header files in a parallel include directory
• use the path in the #include satement as in #include "../src/foo.h"
• use the -I switch to inform the compiler of include locations

So far I like the -I switch solution because it doesn’t involve changing source code when directory structure changes.

Answer 1

For test_foo.c you simply need to tell the compiler where the header files can be found. E.g.

gcc -I../src -c test_foo.c 

Then the compiler will also look into this directory to find the header files. In test_foo.c you write then:

#include 'foo.h' 

EDIT: To link against foo.c, actually against foo.o, you need to mention it in the object file list. I assume you have already the object files, then do after that:

gcc test_foo.o ../src/foo.o -o test