我正在尝试使用SDL和C++制作游戏。
到目前为止,我还没能用它做任何事情。我遵循了Mac的所有说明(我有一个Mac版本10.12.2)和g++http://www.lazyfoo.net/tutorials/SDL/01_hello_SDL/index.php.
现在,我遇到了链接器错误,说他们找不到-l(小写l)选项指定的库。这是我的Makefile:
CC = g++
CFLAGS = -g -Wall -std=c++11
SDL_PATH = /Users/myname/Documents/Code-Libraries/SDL2-2.0.5
SDL_INCLUDE = -I$(SDL_PATH)/include
SDL_LIB = -L$(SDL_PATH) -l/usr/local/lib/libSDL2.a
default: SDL01
SDL01: 01_hello_SDL.cpp
$(CC) $(CFLAGS) 01_hello_SDL.cpp $(SDL_LIB) $(SDL_INCLUDE) -o SDL01
clean:
rm -f SDL01 *.o
我试过-lSDL2。我试过-lSDL。我尝试过-l/usr/local/lib/libSDL2.a。我只尝试过-l选项(无-l选项)和各种写作方式/Users/myname/Documents/Code Libraries/SDL2-2.0.5,而这个选项(/Users/my name/Documents/Code Library/SDL2-2.0.5)给了我…
Undefined symbols for architecture x86_64:
"_SDL_CreateWindow", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_Delay", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_DestroyWindow", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_FillRect", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_GetError", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_GetWindowSurface", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_Init", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_MapRGB", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_Quit", referenced from:
_main in 01_hello_SDL-f65b5c.o
"_SDL_UpdateWindowSurface", referenced from:
_main in 01_hello_SDL-f65b5c.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [SDL01] Error 1
而其他人告诉我,他们找不到该项目的标题。我真的很失落,真的很想得到一些帮助。非常感谢。
第1版:
我做了nm /usr/local/lib/libSDL2.a | grep _SDL_CreateWindow
,得到了
0000000000001cb0 T _SDL_CreateWindow
0000000000000f80 T _SDL_CreateWindowAndRenderer
0000000000007620 t _SDL_CreateWindowAndRenderer_DEFAULT
U _SDL_CreateWindowAndRenderer_REAL
0000000000001cc0 T _SDL_CreateWindowFrom
0000000000009e80 t _SDL_CreateWindowFrom_DEFAULT
U _SDL_CreateWindowFrom_REAL
0000000000009e30 t _SDL_CreateWindow_DEFAULT
U _SDL_CreateWindow_REAL
0000000000000060 T _SDL_CreateWindowAndRenderer_REAL
U _SDL_CreateWindow_REAL
U _SDL_CreateWindow_REAL
00000000000030a0 T _SDL_CreateWindowFrom_REAL
0000000000000760 t _SDL_CreateWindowTexture
0000000000002010 T _SDL_CreateWindow_REAL
U _SDL_CreateWindow_REAL
第2版:
这些是~/Documents/Code Libraries/SDL2-2.0.5/directory:中的文件/目录
Android.mk SDL2.spec.in cmake_uninstall.cmake.in
BUGS.txt TODO.txt configure
CMakeLists.txt VisualC/ configure.in
COPYING.txt VisualC-WinRT/ debian/
CREDITS.txt VisualC.html docs/
INSTALL.txt WhatsNew.txt include/
Makefile.in Xcode/ sdl2-config.cmake.in
Makefile.minimal Xcode-iOS/ sdl2-config.in
Makefile.pandora acinclude/ sdl2.m4
Makefile.psp android-project/ sdl2.pc.in
Makefile.wiz autogen.sh src/
README-SDL.txt build/ test/
README.txt build-scripts/
SDL2.spec cmake/
好吧,多亏了@JohnZwinck,我才弄清楚自己做错了什么。当告诉编译器g++第三方库在哪里时,我给了它错误的位置(-L/Users/myname/Documents/Code-Libraries/SDL2-2.0.5
)和一个对它毫无意义的名称(-lSDL2
)。因此,我做了一些进一步的阅读,以下是https://linux.die.net/man/1/g++:
您可以混合选项和其他参数。在大多数情况下,您使用的顺序无关紧要。当你使用几种相同的选项时,顺序确实很重要;例如,如果您多次指定-L,则会按指定的顺序搜索目录。此外,-l选项的位置也很重要。
链接器选项
对象文件名-library-nostartfiles-nodefaultlibs-nostlib-pie-rdynamic-s-static-static libgcc-shared-shared libgcc-symbolic-T script-Wl,option-Xlinker option-u symbol
目录选项
-Bprefix-Idir-igotedir-Ldir-specs=文件-I---sysroot=dir
因此,基本上,-L目录需要位于-L库之前,因为-L选项告诉g++在哪里查找库,然后-L选项说明它是什么库。如果没有-L之前的-L,g++不知道从-L在哪里查找该库。
如果我错了,请随时纠正我!但这解决了我的问题。