Automatically including multiple source files with -gcc?

0
votes

I created some useful utility functions in C that I want to use in my programs. They are all located in the ../lib folder. I have a header file that contains the function prototypes which I include with `#include "../lib/library.h". However when compiling with gcc I also have to provide the names of the C files that contain the function definitions.

Right now there are only 3 C files in the ../lib folder but this may grow over time. Is there any way to automatically tell gcc to include all of these files (including my main.c file) when compiling my program?

1
c++cgcc
use Makefile or other build tool – Bryan Chen

1 Answers

1
votes

Create a library. If you are on Linux, you have to choose if you want a static library or a shared library. Static libraries are created using archiver command on linux. Google for "ar".

ar cr libtest.a test1.o test2.o

Now you can link with this archive using the -ltest option (ltest is shorthand for libtest you created) with gcc or g++. If your code just has C code then use gcc. If it has both C and C++ then use g++.

As with header files, the linker looks for libraries in some standard places, including the /lib and /usr/lib directories that contain the standard system libraries. If you want the linker to search other directories as well, you should use the -L option, which is the parallel of the -I option for header files.You can use this line to instruct the linker to look for libraries in the /usr/local/lib/MyTest directory before looking in the usual places:

g++ -o reciprocal main.o reciprocal.o -L/usr/local/lib/MyTest -ltest

Although you don’t have to use the -I option to get the preprocessor to search the current directory (for finding you Header file), you do have to use the -L option to get the linker to search the current directory. In particular, you could use the following to instruct the linker to find the test library in the current directory:

gcc -o app app.o -L. -ltest

The shared library creation process is also similar. Once you get the hang of it then you can take care of compilation and linking via a makefile.

(Some part of this post was taken from: Advanced Linux Programming , link: http://www.cse.hcmut.edu.vn/~hungnq/courses/nap/alp.pdf)