Just some example files to show what gcc preprocessor does, needed for the explanation on this blog post: http://while2.ghost.io/how_c_compilers_work_part_2_preprocessor/
Source file main_pp.c has been created by the following command:
gcc -Wall -E -o main_pp.c main.c
GCC version is (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3