GCC - GNU Compiler Collection

Basic Compilation

gcc FILENAME.c -Wall -o OUTPUT_FILE

Useful Options

-Wall – Print all compiler warnings -o – Change the output file

External Libraries

When you have to include headers from other projects using #include <> gcc will search for these header files (.h) and shared object files (.so). When compiling you need to tell GCC to include these files as well.

Using External Libraries

The skinny: Use -l to include libraries in an external

gcc FILENAME.c -l<lib-name>

NOTES

• Order is important. -l<lib-name> has to come after FILENAME.c
• No space between -l and <lib-name>
• Example: To include libmyfunctions.so use -lmyfunctions

Linked Object Directory.

The skinny: Use -L to add a directory with an external .so file

gcc FILENAME.c -L/home/user/lib/ -l<lib-name>

GCC knows where to look for external libraries. Usually developers know put these libraries where GCC can find them, e.g. /usr/lib. However, not all libraries are stored where GCC can find them. In this case you need to add the directory with your shared object to GCC’s search path using -L