Linux Library 1: Static Libraries (.a)

Consider example files:

• ctest1.c

void ctest1(int *i)
{
   *i=5;
}

• ctest2.c

void ctest2(int *i)
{
   *i=100;
}

• prog.c

#include <stdio.h>
void ctest1(int *);
void ctest2(int *);

int main()
{
   int x;
   ctest1(&x);
   printf("Valx=%d\n",x);

   return 0;
}

How to generate a static library (object code archive file) libctest.a?

First of all, Compile *.c to *.o:

$ cc -Wall -c ctest1.c ctest2.c   # -Wall: include warnings

Then create library libctest.a by using ar command:

$ ar -cvq libctest.a ctest1.o ctest2.o

You can list files in library:

$ ar -t libctest.a

ctest1.o
ctest2.o

In the end, linking with static library to get executable file:

$ cc -o prog -L. -lctest

-lctest tells gcc to look for library libctest.a in . (current directory), which is specified by -L..

Read this page for more details.