How to compile with libraries (*.a) with gcc?

[prthealien]

I'm fairly new at this gcc stuff. So I successfully compiled a set of libraries from the source. How do I use them in my program? Do I need to include the library headers in my program? What arguments/options do I pass to gcc?

[Salem]

Say for example your library is in
/home/me/work/thing/lib/libthingy.a
and it's corresponding header file is in
/home/me/work/thing/inc/thingy.h

To compile something using those, say

#include <thingy.h>
int main ( ) {
    doAThing();
    return 0;
}

You would compile with
gcc -I/home/me/work/thing/inc main.c -L/home/me/work/thing/lib -lthingy