未定义的引用`_GetAdaptersAddresses @ 20“ - 但我包括-liphlpapi [英] undefined reference to `_GetAdaptersAddresses@20' - but I included -liphlpapi

问题描述

我用 GCC 在的cygwin 写一些code调用 GetAdaptersAddresses 从 iphlpapi.h 在我的code我设置了 _WIN32_WINNT 以上所要求的 0x0501 并在连接线我已经添加了 -liphlpapi 但链接仍然具有以下失败消息：

  GCC -liphlpapi建立/ OBJ / *。Ø-Wall -Wextra -o建立/斌/ asdf.exe的src / asdf.cpp
/tmp/ccdjLPVY.o:asdf.cpp:(.text+0x153）：未定义的引用`_GetAdaptersAddresses @ 20'
collect2：劳工处返回1退出状态
 

从一些片段 asdf.cpp ：

 ＃如果_WIN32_WINNT＆LT; 0x0501
  指令#warning _WIN32_WINNT设置比0x0501低，固定
  和#undef _WIN32_WINNT
  ＃定义_WIN32_WINNT 0x0501
＃万一
＃包括LT＆;＆winsock2.h GT;
＃包括LT＆;＆iphlpapi.h GT;
 

我知道他们的存在实在可恨：

 字符串/usr/i686-pc-mingw32/sys-root/mingw/lib/libiphlpapi.a |排序| uniq的| grep的GetAdapters
__imp__GetAdaptersAddresses @ 20
__imp__GetAdaptersInfo @ 8
_GetAdaptersAddresses @ 20
_GetAdaptersInfo @ 8
GetAdaptersAddresses
GetAdaptersInfo$字符串/usr/lib/w32api/libiphlpapi.a |排序| uniq的| grep的GetAdapters
__imp__GetAdaptersAddresses @ 20
__imp__GetAdaptersInfo @ 8
_GetAdaptersAddresses @ 20
_GetAdaptersInfo @ 8
GetAdaptersAddresses
GetAdaptersInfo
 

有没有人看到我已经错过了？

编辑：答案

 ＃改变顺序，把连接选项最后：
＃之前：
GCC编译-liphlpapi / OBJ / *。Ø-Wall -Wextra -o建立/斌/ asdf.exe的src / asdf.cpp
＃后：
GCC编译/ OBJ / *。Ø-Wall -Wextra -o建立/斌/ asdf.exe的src / asdf.cpp -liphlpapi
 

解决方案

如这个问题的解释，海湾合作委员会论证事项的顺序。您需要将库纳入移动到依赖于它的对象后。

I'm using gcc under cygwin to write some code that calls GetAdaptersAddresses from iphlpapi.h in my code I've set _WIN32_WINNT above the required 0x0501 and on the linker line I've added -liphlpapi but the linker is still failing with the following message:

gcc -liphlpapi build/obj/*.o -Wall -Wextra -o build/bin/asdf.exe src/asdf.cpp
/tmp/ccdjLPVY.o:asdf.cpp:(.text+0x153): undefined reference to `_GetAdaptersAddresses@20'
collect2: ld returned 1 exit status

Some snippets from asdf.cpp:

#if _WIN32_WINNT < 0x0501
  #warning _WIN32_WINNT was set lower than 0x0501, fixing
  #undef _WIN32_WINNT
  #define _WIN32_WINNT 0x0501
#endif
#include <winsock2.h>
#include <iphlpapi.h>

I know they're there darn it:

strings /usr/i686-pc-mingw32/sys-root/mingw/lib/libiphlpapi.a  | sort | uniq | grep GetAdapters
__imp__GetAdaptersAddresses@20
__imp__GetAdaptersInfo@8
_GetAdaptersAddresses@20
_GetAdaptersInfo@8
GetAdaptersAddresses
GetAdaptersInfo

$strings /usr/lib/w32api/libiphlpapi.a  | sort | uniq | grep GetAdapters
__imp__GetAdaptersAddresses@20
__imp__GetAdaptersInfo@8
_GetAdaptersAddresses@20
_GetAdaptersInfo@8
GetAdaptersAddresses
GetAdaptersInfo

Is anyone seeing what I've missed?

Edit: Answer

# Change the order, put the linker options last:
# Before:
gcc -liphlpapi build/obj/*.o -Wall -Wextra -o build/bin/asdf.exe src/asdf.cpp
# After:
gcc            build/obj/*.o -Wall -Wextra -o build/bin/asdf.exe src/asdf.cpp -liphlpapi

解决方案

As explained in this question, the order of gcc arguments matters. You need to move the library inclusion to after the objects that depend on it.

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