Linux C++ 错误：未定义对“dlopen”的引用
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/956640/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Linux c++ error: undefined reference to 'dlopen'
提问by user101375
I work in Linux with C++ (Eclipse), and want to use a library. Eclipse shows me an error:
我使用 C++ (Eclipse) 在 Linux 中工作，并且想要使用一个库。Eclipse 显示了一个错误：
undefined reference to 'dlopen'
Do you know a solution?
你知道解决办法吗？
Here is my code:
这是我的代码：
#include <stdlib.h>
#include <stdio.h>
#include <dlfcn.h>
int main(int argc, char **argv) {
void *handle;
double (*desk)(char*);
char *error;
handle = dlopen ("/lib/CEDD_LIB.so.6", RTLD_LAZY);
if (!handle) {
fputs (dlerror(), stderr);
exit(1);
}
desk= dlsym(handle, "Apply");
if ((error = dlerror()) != NULL) {
fputs(error, stderr);
exit(1);
}
dlclose(handle);
}
采纳答案by Masci
You have to link against libdl, add
你必须链接到 libdl，添加
-ldl
-ldl
to your linker options
到您的链接器选项
回答by Rob
You needed to do something like this for the makefile:
您需要为 makefile 执行以下操作：
LDFLAGS='-ldl'
make install
That'll pass the linker flags from make through to the linker. Doesn't matter that the makefile was autogenerated.
这会将链接器标志从 make 传递到链接器。生成文件是自动生成的并不重要。
回答by Deqing
I met the same problem even using -ldl.
即使使用-ldl.
Besides this option, source files need to be placed before libraries, see undefined reference to `dlopen'.
除了这个选项，源文件需要放置在库之前，参见undefined reference to `dlopen'。
回答by knocte
@Masci is correct, but in case you're using C (and the gcccompiler) take in account that this doesn't work:
@Masci 是正确的，但如果您使用 C（和gcc编译器），请考虑到这不起作用：
gcc -ldl dlopentest.c
But this does:
但这确实：
gcc dlopentest.c -ldl
Took me a bit to figure out...
花了我一点时间来弄清楚......
回答by bawey
The topic is quite old, yet I struggled with the same issue today while compiling cegui 0.7.1 (openVibe prerequisite).
这个话题已经很老了，但我今天在编译 cegui 0.7.1（openVibe 先决条件）时遇到了同样的问题。
What worked for me was to set: LDFLAGS="-Wl,--no-as-needed"in the Makefile.
对我有用的是设置：LDFLAGS="-Wl,--no-as-needed"在 Makefile 中。
I've also tried -ldlfor LDFLAGSbut to no avail.
我也尝试过-ldl，LDFLAGS但无济于事。
回答by user2948547
you can try to add this
你可以尝试添加这个
LIBS=-ldl CFLAGS=-fno-strict-aliasing
to the configure options
到配置选项
回答by Amitk
In order to use dl functions you need to use the -ldl flag for the linker.
为了使用 dl 函数，您需要为链接器使用 -ldl 标志。
how you do it in eclipse ?
你如何在日食中做到这一点？
Press Project--> Properties--> C/C++ build--> Settings--> GCC C++ Linker-->
Libraries--> in the "Libraries(-l)" box press the "+" sign--> write "dl" (without the quotes)-> press ok--> clean & rebuildyour project.
按Project--> Properties--> C/C++ build--> Settings--> GCC C++ Linker-->
Libraries--> 在“Libraries(-l)”框中按“+”号--> 写“ dl”（不带引号）-> 按确定-->清理并重建您的项目。
回答by flerb
$gcc -o program program.c -l <library_to_resolve_program.c's_unresolved_symbols>
A good description of why the placement of -l dl matters
But there's also a pretty succinct explanation in the docs From $man gcc
但是在 $man gcc 的文档中也有一个非常简洁的解释
-llibrary -l library Search the library named library when linking. (The second alternative with the library as a separate argument is only for POSIX compliance and is not recommended.)
-llibrary -l library Search the library named library when linking. (The second alternative with the library as a separate argument is only for POSIX compliance and is not recommended.)
It makes a difference where in the command you write this option; the
linker searches and processes libraries and object files in the order
they are specified. Thus, foo.o -lz bar.o searches library z after
file foo.o but before bar.o. If bar.o refers to functions in z,
those functions may not be loaded.
回答by vulcan raven
this doesn't work:
gcc -ldl dlopentest.cBut this does:
gcc dlopentest.c -ldlThat's one annoying "feature" for sure
这不起作用：
gcc -ldl dlopentest.c但这确实：
gcc dlopentest.c -ldl这肯定是一个令人讨厌的“功能”
I was struggling with it when writing heredoc syntax and found some interesting facts. With CC=Clang, this works:
我在编写 heredoc 语法时遇到了它，并发现了一些有趣的事实。使用CC=Clang，这有效：
$CC -ldl -x c -o app.exe - << EOF
#include <dlfcn.h>
#include <stdio.h>
int main(void)
{
if(dlopen("libc.so.6", RTLD_LAZY | RTLD_GLOBAL))
printf("libc.so.6 loading succeeded\n");
else
printf("libc.so.6 loading failed\n");
return 0;
}
EOF
./app.exe
as well as all of these:
以及所有这些：
$CC -ldl -x c -o app.exe - << EOF$CC -x c -ldl -o app.exe - << EOF$CC -x c -o app.exe -ldl - << EOF$CC -x c -o app.exe - -ldl << EOF
$CC -ldl -x c -o app.exe - << EOF$CC -x c -ldl -o app.exe - << EOF$CC -x c -o app.exe -ldl - << EOF$CC -x c -o app.exe - -ldl << EOF
However, with CC=gcc, only the last variant works; -ldlafter -(the stdin argument symbol).
但是，对于CC=gcc，只有最后一个变体有效；-ldl之后-（标准输入参数符号）。
