visual C++链接器不能将外部符号与静态libcurl一起使用
visual C++ linker cant use external symbol with static libcurl
我有这个简单的C++代码。
#include <iostream>
#include <windows.h>
#include <Lmcons.h>
#define CURL_STATICLIB
#include <iostream>
#include <fstream>
#include <curl.h>
#include <stdio.h>
#pragma comment(lib, "ws2_32.lib")
#pragma comment(lib, "curl\libeay32.lib")
#pragma comment(lib, "curl\openldap.lib")
#pragma comment(lib, "curl\ssleay32.lib")
#if defined _DEBUG
#pragma comment(lib, "curl\lib\Debug\curllib_static.lib")
#else
#pragma comment(lib, "curl\lib\Release\curllib_static.lib")
#endif
using namespace std;
int main()
{
TCHAR name [ UNLEN + 1 ];
DWORD size = UNLEN + 1;
if (GetUserName( (TCHAR*)name, &size ))
wcout << "Hello, " << name << "!n";
else
wcout << "Hello, unnamed person!n";
CURL *curl;
CURLcode res;
curl_version();
/* In windows, this will init the winsock stuff */
curl_global_init(CURL_GLOBAL_ALL);
/* get a curl handle */
curl = curl_easy_init();
if(curl) {
/* First set the URL that is about to receive our POST. This URL can
just as well be a https:// URL if that is what should receive the
data. */
curl_easy_setopt(curl, CURLOPT_URL, "http://requestb.in/19l9fjg1");
/* Now specify the POST data */
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "name=daniel&project=curl");
/* Perform the request, res will get the return code */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK)
fprintf(stderr, "curl_easy_perform() failed: %sn",
curl_easy_strerror(res));
/* always cleanup */
curl_easy_cleanup(curl);
}
curl_global_cleanup();
system("PAUSE");
return 0;
}
我的目录树。
X
| app.cpp
|
+---curl
| | CHANGES
| | curl.exe
| | curllib.dll
| | libcurl_imp.lib
| | libeay32.dll
| | libeay32.lib
| | openldap.dll
| | openldap.lib
| | README
| | ssleay32.dll
| | ssleay32.lib
| |
| +---docs
| | | BINDINGS
| | | [...]
| | | VERSIONS
| | |
| | +---examples
| | | 10-at-a-time.c
| | | [...]
| | | threaded-ssl.c
| | |
| | ---libcurl
| | ABI
| | [...]
| | Makefile.in
| |
| +---include
| | | Makefile.am
| | | [...]
| | | README
| | |
| | ---curl
| | curl.h
| | [...]
| | types.h
| |
| +---lib
| | +---Debug
| | | curllib.dll
| | | curllib.lib
| | | curllib_static.lib
| | |
| | ---Release
| | curllib.dll
| | curllib.lib
| | curllib_static.lib
| |
| ---src
| +---DLL-Debug
| | curl.exe
| | curllib.dll
| | openldap.dll
| |
| +---DLL-Release
| | curl.exe
| | curllib.dll
| | openldap.dll
| |
| +---LIB-Debug
| | curl.exe
| |
| ---LIB-Release
| curl.exe
|
+---Debug
| app.obj
| [...]
| vc110.pdb
|
---Release
app.obj
[...]
vc110.pdb
这就是我的设定。
Linker -> General -> Additional library directories
XcurllibRelease;Xcurl;%(AdditionalLibraryDirectories)
Linker -> Input -> Additional dependences
$(ProjectDir)curllibDebugcurllib_static.lib;%(AdditionalDependencies)
VC++-Directories -> Include directories
$(ProjectDir)curlincludecurl;$(IncludePath)
VC++-Directories -> Library directories
$(ProjectDir)curllibRelease;$(LibraryPath)
**$（ProjectDir）是X**
错误
Error 2 error LNK2005: _calloc already defined in LIBCMT.lib(calloc.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 3 error LNK2005: _realloc already defined in LIBCMT.lib(realloc.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 4 error LNK2005: _free already defined in LIBCMT.lib(free.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 5 error LNK2005: _malloc already defined in LIBCMT.lib(malloc.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 6 error LNK2005: _strrchr already defined in LIBCMT.lib(strrchr.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 7 error LNK2005: _strchr already defined in LIBCMT.lib(strchr.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 8 error LNK2005: _fwrite already defined in LIBCMT.lib(fwrite.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 9 error LNK2005: ___iob_func already defined in LIBCMT.lib(_file.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 10 error LNK2005: _strtoul already defined in LIBCMT.lib(strtol.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 11 error LNK2005: _memmove already defined in LIBCMT.lib(memmove.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 12 error LNK2005: _tolower already defined in LIBCMT.lib(tolower.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 13 error LNK2005: _atoi already defined in LIBCMT.lib(atox.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 14 error LNK2005: _isxdigit already defined in LIBCMT.lib(_ctype.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 15 error LNK2005: _isdigit already defined in LIBCMT.lib(_ctype.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 16 error LNK2005: _isspace already defined in LIBCMT.lib(_ctype.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 17 error LNK2005: __strtoi64 already defined in LIBCMT.lib(strtoq.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 18 error LNK2005: _memchr already defined in LIBCMT.lib(memchr.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 19 error LNK2005: _fclose already defined in LIBCMT.lib(fclose.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 20 error LNK2005: _strtol already defined in LIBCMT.lib(strtol.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 21 error LNK2005: _sprintf already defined in LIBCMT.lib(sprintf.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 22 error LNK2005: _fflush already defined in LIBCMT.lib(fflush.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 23 error LNK2005: __errno already defined in LIBCMT.lib(dosmap.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 24 error LNK2005: __lseeki64 already defined in LIBCMT.lib(lseeki64.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 25 error LNK2005: _getenv already defined in LIBCMT.lib(getenv.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 26 error LNK2005: _isalnum already defined in LIBCMT.lib(_ctype.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 27 error LNK2005: _isalpha already defined in LIBCMT.lib(_ctype.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 28 error LNK2005: "private: __thiscall type_info::type_info(class type_info const &)" (??0type_info@@AAE@ABV0@@Z) already defined in LIBCMT.lib(typinfo.obj). XMSVCRT.lib(ti_inst.obj) X
Error 29 error LNK2005: "private: class type_info & __thiscall type_info::operator=(class type_info const &)" (??4type_info@@AAEAAV0@ABV0@@Z) already defined in LIBCMT.lib(typinfo.obj). XMSVCRT.lib(ti_inst.obj) X
Error 30 error LNK2005: __strdup already defined in LIBCMT.lib(strdup.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 31 error LNK2005: __close already defined in LIBCMT.lib(close.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 32 error LNK2005: __fileno already defined in LIBCMT.lib(fileno.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 33 error LNK2005: __read already defined in LIBCMT.lib(read.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 34 error LNK2005: __strnicmp already defined in LIBCMT.lib(strnicmp.obj). XMSVCRT.lib(MSVCR110.dll) X
Error 35 error LNK1169: One or more multiply defined symbols found in. X..ReleaseX.exe X
如果我用上面的curllib.lib替换curllib_static.lib，我会得到一个libcurl.dll丢失的错误。
因为AND，因为我不想在我的目录中有额外的libcurl.dll，所以我使用静态libcurl。
如何解决
我正在将此libcurl与Microsoft Visual Studio 2012一起使用。http://curl.haxx.se/download/libcurl-7.19.3-win32-ssl-msvc.zip
像这样的问题在Visual C++中很常见，很难准确描述如何修复它们。你需要非常小心，真正了解你包括哪些库，但这里没有足够的信息来解决这个问题。
一个常见的原因是使用了错误的运行库。在VS中，这将是/MT和/MD开关之间的区别，但您似乎在使用makefile，因此这可能不适用。LIBCMT是一个多线程库，但看起来您可能也包含了另一个库。
我不建议使用#pragmas来包含链接库。把它们放在makefile中，这样你就可以在一个地方看到所有内容。
通常，在启用日志记录的情况下运行链接器可以准确地查看调用了哪些库
您的目录树和设置没有什么帮助，但一个包含makefile的最小完整项目可能会让这里的人诊断问题。
stackoverflow中有一个老问题，它会引发一个非常相似的问题，看看这里：
错误LNK2005:xxx已在MSVCRT.lib（MSVCR100.dll）C:\something\LIBCMT.lib（setlocal.obj）中定义
这里的另一个链接：
LIBCMTD.lib和MSVCRTD.lib 的LNK2005错误
我希望它能帮助你！
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