我在linux中。我的Makefile文件是这个
main2: main.cpp
g++ -c $(LIBS) $(CFLAGS) -fPIC main.cpp
g++ -shared main.o -o main.so
在哪里,
SDL_CFLAGS := $(shell sdl-config --cflags)
SDL_LDFLAGS := $(shell sdl-config --libs)
CC = gcc
COPTS = -g -Wall
CFLAGS = $(SDL_CFLAGS)
LIBS = -lstdc++ -lSDL $(SDL_LDFLAGS) -L/usr/X11R6/lib -lGL -lGLU
哪个运行
g++ -c -lstdc++ -lSDL -L/usr/lib -lSDL -L/usr/X11R6/lib -lGL -lGLU -I/usr/include/SDL -D_GNU_SOURCE=1 -D_REENTRANT -fPIC main.cpp
g++ -shared main.o -o main.so
现在,这可以正常工作了。将生成main.o和main.so文件。
但是,当我尝试将main.os与python ctypes链接时
from ctypes import * import os
libtest = cdll.LoadLibrary(os.getcwd()+ '/main.so') libtest.main_loop()
libtest.main_loop()
我得到这个错误
>>> libtest = cdll.LoadLibrary(os.getcwd() + '/main.so')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.6/ctypes/__init__.py", line 431, in LoadLibrary
return self._dlltype(name)
File "/usr/lib/python2.6/ctypes/__init__.py", line 353, in __init__
self._handle = _dlopen(self._name, mode)
OSError: /home/atomos/DF/open_gl_client/ctypes_client/main.so: undefined symbol: glEnd
我不确定是否正确创建了链接库。如何创建可以加载的链接库?
我是否需要为从main.cpp导入的每个库创建.o和.os文件,还是该文件会自动处理?
我不知道编译器或链接器在做什么,但是它适用于没有导入的简单示例,但是对于导入opengl库的cpp文件,则会出现该错误。
- - 更新 - -
反对main.so yield
ldd main.so
linux-gate.so.1 => (0xb7755000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0xaf625000)
libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0xaf5ff000)
libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0xaf4a4000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0xaf485000)
/lib/ld-linux.so.2 (0xb7756000)
- - 更新 - -
我在第二个编译步骤中运行了不带-shared标志的g++,并收到此错误
g++ main.o -o main.so
main.o: In function `Texture_map_list::add_texture(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)':
main.cpp:(.text+0xf0fe): undefined reference to `glGenTextures'
main.cpp:(.text+0xf2ba): undefined reference to `glBindTexture'
main.cpp:(.text+0xf2d7): undefined reference to `glTexParameterf'
main.cpp:(.text+0xf2f4): undefined reference to `glTexParameterf'
main.cpp:(.text+0xf310): undefined reference to `glTexParameteri'
main.cpp:(.text+0xf32c): undefined reference to `glTexParameteri'
main.cpp:(.text+0xf365): undefined reference to `gluBuild2DMipmaps'
main.o: In function `init()':
main.cpp:(.text+0xf457): undefined reference to `SDL_Init'
main.cpp:(.text+0xf46d): undefined reference to `SDL_WM_SetCaption'
main.cpp:(.text+0xf472): undefined reference to `SDL_GetVideoInfo'
main.cpp:(.text+0xf480): undefined reference to `SDL_GetError'
main.cpp:(.text+0xf497): undefined reference to `SDL_Quit'
main.cpp:(.text+0xf4e2): undefined reference to `SDL_GL_SetAttribute'
main.cpp:(.text+0xf505): undefined reference to `SDL_SetVideoMode'
main.cpp:(.text+0xf513): undefined reference to `SDL_GetError'
main.cpp:(.text+0xf52a): undefined reference to `SDL_Quit'
main.cpp:(.text+0xf559): undefined reference to `glClearColor'
main.cpp:(.text+0xf565): undefined reference to `glEnable'
main.cpp:(.text+0xf571): undefined reference to `glMatrixMode'
main.cpp:(.text+0xf576): undefined reference to `glLoadIdentity'
main.cpp:(.text+0xf5a2): undefined reference to `gluPerspective'
main.o: In function `process_keypresses()':
main.cpp:(.text+0x10678): undefined reference to `SDL_PollEvent'
main.cpp:(.text+0x109a1): undefined reference to `SDL_PollEvent'
main.o: In function `main_loop':
main.cpp:(.text+0x10d76): undefined reference to `SDL_GetKeyState'
main.cpp:(.text+0x10d9f): undefined reference to `SDL_Quit'
main.o: In function `render()':
main.cpp:(.text+0x10e00): undefined reference to `SDL_GetMouseState'
main.cpp:(.text+0x10e90): undefined reference to `SDL_GetMouseState'
main.cpp:(.text+0x10f94): undefined reference to `glClear'
main.cpp:(.text+0x10fa0): undefined reference to `glMatrixMode'
main.cpp:(.text+0x10fa5): undefined reference to `glLoadIdentity'
main.cpp:(.text+0x11081): undefined reference to `gluLookAt'
main.cpp:(.text+0x11120): undefined reference to `glTranslatef'
main.cpp:(.text+0x1114d): undefined reference to `glRotatef'
main.cpp:(.text+0x1117a): undefined reference to `glRotatef'
main.cpp:(.text+0x1119e): undefined reference to `SDL_GL_SwapBuffers'
main.o: In function `draw_plane(float, float, float)':
main.cpp:(.text+0x111d8): undefined reference to `glColor3f'
main.cpp:(.text+0x111e4): undefined reference to `glBegin'
main.cpp:(.text+0x1120b): undefined reference to `glVertex3f'
....
最佳答案
首先,请注意,如果您不构建共享库,这将更易于调试。您正在使用-shared进行构建,因此只有在Python中动态加载库后,链接器错误才会发生。在调试时关闭-shared,当您尝试链接时,您将在命令行上看到错误:
g++ main.o -o main
main.o: In function `main':
main.cpp:(.text+0x1d): undefined reference to `glBegin'
main.cpp:(.text+0x22): undefined reference to `glEnd'
collect2: ld returned 1 exit status
现在的问题是,您正在将链接器参数传递给编译器。我看到您在Makefile中将
CFLAGS
和LIBS
很好地分开了。好的。但是,您在第一行中同时传递了$(LIBS)
和$(CFLAGS)
来构建main.o。该行上的LIBS
将被忽略,因为它们是链接标志。在第二行中,您实际上是在构建最终可执行文件,而您没有传递
$(LIBS)
,因此该程序未与libGL或任何其他库链接。因此,只需简单地修复您的makefile:
main2: main.cpp
g++ -c $(CFLAGS) -fPIC main.cpp
g++ -shared main.o $(LIBS) -o main.so
编辑:从那时起,我意识到在GCC中,您必须always put the libraries after the object files,因此我相应地更改了makefile的最后一行。
关于c++ - 如何正确链接并构建动态链接库?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/4300238/