Making and using of static library

The library files

         A library is a collection of precompiled methods . Linux The location of the system repository is generally ： /lib and /usr/lib.
stay 64 Some libraries on a bit system may also be stored in /usr/lib64 Next . The header file of the library is usually stored in
/usr/include Or its subdirectories .
         There are two kinds of libraries. , One is a static library , The command rule is libxxx.a, One is the shared library , The command rule is libxxx.so.

Generation of static library

a.c b.c head.h

  The above is to generate a static library “.c” file , among “head.h” Is the declaration of the function ,“a.c”,“b.c” Is the definition of a function

        1. Will need to generate all of the library's files “.c” File compiled into “.o” file

gcc -c a.c
gcc -c b.c

        2. Use ar The command will all the... Generated in the first step “.o” File generation static library

ar crv libab.a a.o b.o

  among ：c Is to create a library ;r Is to add methods to the library ;v Show the process

The use of static libraries

#include "head.h"

  The test code needs to contain the specified library file

gcc test.c -o test -L. -lhead

• -L： Specify the storage path of the library
• -l： Specify the name of the library （ There is no need for the front ‘lib’ And extension ‘.a’）

Project directory

• include： Store the header file of the project
• lib： The library files
• src： Source code file

Use of static libraries in the project

The structure diagram is shown below

        1. take src All the files that need to generate the library in “.c” File compiled into “.o” file , Note that the header file is in the include in , Therefore, you need to specify include Search directory containing files .

gcc -c add.c sub.c mult.c div.c -I ../include/

        2. Use ar The command will all the... Generated in the first step “.o” File generation static library , You need to specify the lib Folder

ar rcs ../lib/libcalc.a add.o div.o mult.o sub.o

        3.  link ： You need to specify the include The header file of the folder and specify the location of the library file and the name of the library file

gcc main.c -o main -I ./include/ -L ./lib -l calc