Linux C: Generation and use of static and dynamic libraries

Scene:

The main function requires two interfaces, a summation function, and a print function.

int sum (int i, int j); The number of two int is calculated.

void Show (int i, char* name); Prints the value of I and its name.

Now, you need to make:

A static library LIBCALC.A, providing the interface of sum;

A dynamic library libshow.so that provides the interface for show.

#include <stdio.h>#include"calc.h"#include"show.h"intMainvoid){    ints; inti =1; intj =2; S=sum (I,J); Show (I,"I"); Show (J,"J"); Show (S,"sum");}

CALC.C, calc.h

" calc.h " int sum (intint  j) {    return(i+j);} ~        

#ifndef __calc_h__ #define __calc_h__int sum (intint  j); #endif

SHOW.C, Show.h

" show.h " void Show (intChar* name) {    printf ("%s=%d\n " , name, i);}

#ifndef __show_h__ #define __show_h__void SHOW (intChar* name); #endif~         

Makefile:

CC = gccall:mainmain:libcalc.a main.c libshow.so    -o main main.c-l.-lcalc  -lshow
LIB:LIBCALC.A libshow.solibcalc.a:calc.o        ar CRS libcalc.a calc.ocalc.o:calc.c        -C calc.c-o Calc. OLIBSHOW.SO:SHOW.O        -shared-o libshow.so show.oshow.o:show.c        -fpic-wall-c show.c-o show.o
Clean:    -rf *.o *.so *.a Main

Input: Make all---build libcalc.a,libshow.so Library and main executable program

Make lib---build libcalc.a,libshow.so library

Make clean---Clear the target file

Input: export ld_library_path= ' pwd '---Add current path to dynamic library PATH environment variable ld_library_path

[[email protected] libshow]# export ld_library_path= ' pwd '
[Email protected] libshow]# echo $LD _library_path
/work/jz2440/test/libshow\

Enter:./main test results.

I=1
j=2
Sum=3

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Knowledge about dynamic libraries and static libraries:

1. Makefile example of Linux compiled dynamic libraries and static libraries http://blog.csdn.net/shaoxiaohu1/article/details/46943417

2. Three ways to properly locate and load the loader into the dynamic library:

A. Move libx.so to the system library file directory

B. Export ld_library_path= $LD _library_path: ' pwd '

C. Use the configuration file to tell the system the path to the dynamic library.

Vi/etc/ld.so.conf.d/xxxx.conf

/work/jz2440/test/libshow

3. ldd xxxx View dependent dynamic library files

[Email protected] libshow]# LDD main
Linux-vdso.so.1 = (0x00007fff1edc0000)
libshow.so =/work/jz2440/test/libshow/libshow.so (0x00002ad8d3511000)
libc.so.6 =/lib64/libc.so.6 (0x0000003a4fc00000)
/lib64/ld-linux-x86-64.so.2 (0x0000003a4f800000)

Linux C: Generation and use of static and dynamic libraries