Linux下创建静态、动态库

Linux下创建静态、动态库

源码

1: -----------a.cpp---------------

2: #include

3: int a(int i)

4: {

5:         std::printf("in a(int a) %d/n", i);

6:         return 0;

7: }

8: -----------b.cpp----------------

9: #include

10: int b(char *s)

11: {

12:         std::cout<<"in int b(char *s): "<  13:         return 0;

14: }

15: ----------main.cpp--------------

16: #include

17: using namespace std;

18: int a(int i);

19: int b(char *s);

20: int main()

21: {

22:         a(5);

23:         b("ok");

24:         printf("in main/n");

25:         return 0;

26: }

静态库

1、编译生成a.o b.o 文件

# g++ -c a.cpp b.cpp

2、生成archive 文件libtest.a  c-创建  r-将文件加入libtest.a

#ar rc libtest.a a.o b.o

3、指定静态库libtest.a 进行编译

# g++ -o main main.cpp libtest.a

运行结果

# ./a.out

in a(int a) 5

in int b(char *s): ok

in main

对于libtest.a直接将里面的代码拷贝出来相当于静态编译

动态库

1、编译生成a.o b.o文件   -fPIC生成.o文件时用相对地址实现代码位置无关

# g++ -fPIC a.cpp b.cpp

2、生成动态库libtest.so

# g++ -shared -o libtest.so a.o b.o

3、指定动态库libtest.so进行编译

# g++ main.cpp  ./libtest.so

查看动态连接库

# ldd a.out

        ./libtest.so => ./libtest.so (0x40014000)

        libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 (0x4002e000)

        libm.so.6 => /lib/i686/libm.so.6 (0x40071000)

        libc.so.6 => /lib/i686/libc.so.6 (0x42000000)

        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

其他

1、动态连接库3时如果

# g++ main.cpp libtest.so

编译可通过但运行出错在默认库路径下找不到libtest.so库

# ./a.out

./a.out: error while loading shared libraries: libtest.so: cannot open shared object file: No such

file or directory

查看连接库

# ldd a.out

        libtest.so => not found

        libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 (0x4002c000)

        libm.so.6 => /lib/i686/libm.so.6 (0x4006f000)

        libc.so.6 => /lib/i686/libc.so.6 (0x42000000)

        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

2、方便使用可以将静态库libtest.a或者动态库 libtest.so拷贝到默认库的查找路径里/lib或者/usr/lib里

编译时直接

#g++ main.cpp -ltest

-l 自动进行库名称扩展

# ldd a.out

        libtest.so => /usr/lib/libtest.so (0x4002b000)

        libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 (0x4002e000)

        libm.so.6 => /lib/i686/libm.so.6 (0x40071000)

        libc.so.6 => /lib/i686/libc.so.6 (0x42000000)

        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

静态情况

# g++ main.cpp -ltest

# ldd a.out

        libstdc++-libc6.2-2.so.3 => /usr/lib/libstdc++-libc6.2-2.so.3 (0x4002b000)

        libm.so.6 => /lib/i686/libm.so.6 (0x4006f000)

        libc.so.6 => /lib/i686/libc.so.6 (0x42000000)

        /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

3、静态库中2生成archive后可能需要 ranlib libtest.a 将内容的索引写入libtest.a中供ld连接时使用

4、-l选项要放在所编译文件的后面，

在前面会出错

# g++ -ltest main.cpp

/tmp/ccbQK3kY.o: In function `main'''':

/tmp/ccbQK3kY.o(.text+0xc): undefined reference to `a(int)''''

/tmp/ccbQK3kY.o(.text+0x1c): undefined reference to `b(char *)''''

collect2: ld returned 1 exit status