I have one C++ project with settings of Unicode as character set and /clr option for common language run time support. I am calling some function of MFC dll (with setting of MultiByte character set) and I am getting some liking error on those functions which are using wchar_t. Same dll is working file for those unicode c++ projects where /clr option is not set (i.e. no common language run time support). I have done the google and tried some thing like:--
Replace Cstring with std:string but both are giving same error.
Example for std: string:--
error LNK2001: unresolved external symbol "public: __thiscall
CEventLog::CEventLog(wchar_t const *)" (??0CEventLog##QAE#PB_W#Z)
for Cstring:--
error LNK2019: unresolved external symbol "public: bool __thiscall
CIITAdoField::GetValue(class ATL::CStringT > > &)"
(?GetValue#CIITAdoField##QAE_NAAV?$CStringT#_WV?$StrTraitMFC_DLL#_WV?$ChTraitsCRT#_W#ATL#####ATL###Z)
referenced in function "public: bool __thiscall
Iit::DataFeedSvr::SpeedCache::CacheLoader > >,class
Iit::DataFeedSvr::SpeedCache::HolidayScheduleInfo,struct
Iit::DataFeedSvr::SpeedCache::HolidayScheduleSpeedCacheParam>
::Reload(class Iit::DataFeedSvr::SpeedCache::DoubleKeyCacheInstance > >,class
Iit::DataFeedSvr::SpeedCache::HolidayScheduleInfo,struct
Iit::DataFeedSvr::SpeedCache::HolidayScheduleSpeedCacheParam> &,class
CIITAdoRecordset &,enum
Iit::DataFeedSvr::SpeedCache::ERefreshType,class
Iit::DataFeedSvr::SpeedCache::CacheObserver const *)"
(?Reload#?$CacheLoader#V?$DoubleKeyCacheInstance#JV?$CStringT#_WV?$StrTraitMFC_DLL#_WV?$ChTraitsCRT#_W#ATL#####ATL##VHolidayScheduleInfo#SpeedCache#DataFeedSvr#Iit##UHolidayScheduleSpeedCacheParam#456##SpeedCache#DataFeedSvr#Iit###SpeedCache#DataFeedSvr#Iit##QAE_NAAV?$DoubleKeyCacheInstance#JV?$CStringT#_WV?$StrTraitMFC_DLL#_WV?$ChTraitsCRT#_W#ATL#####ATL##VHolidayScheduleInfo#SpeedCache#DataFeedSvr#Iit##UHolidayScheduleSpeedCacheParam#456##234#AAVCIITAdoRecordset##W4ERefreshType#234#PBVCacheObserver#234##Z)
I have checked the setting like "Treat Wchar_t as Built in type" and it is file.
I have tried to explicitly export function and class using __declspec(dllexport) but no luck.
I can not change my project from unicode to multibyte or can not change the setting of /clr option as it starts giving other error.
Please suggest the solution. Thanks in advance.
Do a 'dumpbin' on the external DLL to see what's exported. If your CEventLog::CEventLog is not exporting a char based constructor you won't be able to import it, simple as that.
It doesn't look from your example that the /clr switch is causing the problem. Try creating a brand new Unicode project (without the CLR) just to check you really can link to the external DLL.
Related
I've made a static library project and I added it to the solution that has a project which uses the library.
I included the class I needed from it in the main project like I would with another static library but it throws these errors:
error LNK2019: unresolved external symbol "public: __thiscall NetworkingLib::Base::Base(void)" (??0Base#NetworkingLib##QAE#XZ) referenced in function _SDL_main
error LNK2019: unresolved external symbol "public: void __thiscall NetworkingLib::Base::Connect(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?Connect#Base#NetworkingLib##QAEXV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std##0#Z) referenced in function _SDL_main
I have no idea what is going wrong. I checked with another project that uses a library in the same way and I can't find any differences. Any help detecting the problem?
The class NetworkingLib::Base has a method I want to use. So what I did in the main project is:
#include "../NetworkLibrary/Base.h"
NetworkingLib::Base *m_pNetworkObj;
m_pNetworkObj = new NetworkingLib::Base();
m_pNetworkObj->Connect("localhost", "80");
I don't think there's anything wrong with this so the problem must be elsewhere.
It's not enough to have the static library in the same solution. You have to pass it to the linker of the project that uses it.
In Visual Studio, the best way to do this is by adding a "Project Reference". This sets up the dependency so that the projects build in the correct order, and also picks the version of the static library matching the consuming project, be that Debug vs Release, x86 vs x64, etc.
I have a third party libs. (msvc10) a MT/MD (Static cfgs's) and dynamic DLL cfg.
I have qt + msvc10 express + win sdk.7
Ok , I use the existing examples offered, (using the libs) I can't compile ..... I have 4 unresolved external errors of the same lib.
(But I have zero errors for the others)
I have not support for these lib...... (but they are legal, I am a member without rights)
Which are the steps to investigate a possible fix? Where I have to look ?
Thanks.
Edit 1:
The errors was:
TD_ExamplesCommon.lib(ExHostAppServices.obj) : error LNK2019: unresolved external symbol __imp__RegEnumValueW#32 referenced in function "public: virtual bool __thiscall ExHostAppServices::ttfFileNameByDescriptor(class OdTtfDescriptor const &,class OdString &)" (?ttfFileNameByDescriptor#ExHostAppServices##UAE_N ABVOdTtfDescriptor##AAVOdString###Z)
TD_ExamplesCommon.lib(ExHostAppServices.obj) : error LNK2019: unresolved external symbol __imp__RegCloseKey#4 referenced in function "public: virtual bool __thiscall ExHostAppServices::ttfFileNameByDescriptor(class OdTtfDescriptor const &,class OdString &)" (?ttfFileNameByDescriptor#ExHostAppServices##UAE_N ABVOdTtfDescriptor##AAVOdString###Z)
TD_ExamplesCommon.lib(ExHostAppServices.obj) : error LNK2019: unresolved external symbol __imp__RegQueryValueExW#24 referenced in function "public: virtual bool __thiscall ExHostAppServices::ttfFileNameByDescriptor(class OdTtfDescriptor const &,class OdString &)" (?ttfFileNameByDescriptor#ExHostAppServices##UAE_N ABVOdTtfDescriptor##AAVOdString###Z)
TD_ExamplesCommon.lib(ExHostAppServices.obj) : error LNK2019: unresolved external symbol __imp__RegOpenKeyExW#20 referenced in function "public: virtual bool __thiscall ExHostAppServices::ttfFileNameByDescriptor(class OdTtfDescriptor const &,class OdString &)" (?ttfFileNameByDescriptor#ExHostAppServices##UAE_N ABVOdTtfDescriptor##AAVOdString###Z)
..\exe\OdaQtApp.exe : fatal error LNK1120: 13 unresolved externals
During this post I have received a solution: I have to link with Advapi32.lib...
My question is : how can I know this ?
I have tried the dependencyywalker, but it cant use the .lib's....
During this post I have received a solution: I have to link with Advapi32.lib... My question is : how can I know this?
When you get an "unresolved external" error from the linker, that means that it was looking for a match for a function or variable name that some object file needs and the linker was unable to find that name defined in one of the object files or libraries.
Start by looking at the first of these errors (I've reformatted it a bit to make it slightly more readable - I encourage yo to do the same next time you come across one of these):
TD_ExamplesCommon.lib(ExHostAppServices.obj) : error LNK2019: unresolved external symbol
__imp__RegEnumValueW#32 referenced in function
"public: virtual bool __thiscall ExHostAppServices::ttfFileNameByDescriptor(
class OdTtfDescriptor const &,class OdString &)"
(?ttfFileNameByDescriptor#ExHostAppServices##UAE_N ABVOdTtfDescriptor##AAVOdString###Z)
There's a lot of stuff in that error message (much of it may look like garbage). Fortunately, much of it can be ignored in most cases. The most important item is that the linker is looking for the symbol __imp__RegEnumValueW#32 The name has some gunk on it, but fortunately it's pretty recognizable anyway.
the __imp__ prefix indicates it's looking for a DLL import. In nearly all cases that can be ignored for your purposes.
the #32 suffix is something the Microsoft compiler adds to function names for certain calling conventions. It's also generally not important for your purposes (for the record it indicates that the function expects 32 bytes of argument data)
So we're left with the fact that the linker is looking for RegEnumValueW. That looks a lot like the name of a Win32 API.
If you look at the docs for RegEnumValueW (or RegEnumValue, since many Win32 APIs have both an A and a W variant to handle ANSI/UNICODE builds) we'll find in the documentation this bit of information:
Requirements
Minimum supported client Windows 2000 Professional
Minimum supported server Windows 2000 Server
Header Winreg.h (include Windows.h)
>> Library Advapi32.lib
DLL Advapi32.dll
Unicode and ANSI names RegEnumValueW (Unicode) and
RegEnumValueA (ANSI)
That's how you know you need advapi32.lib.
So in the future, when you get an "unresolved external" error from the linker, just ignore most of the gunk in the error message and concentrate on the symbol it says it can't find - that should lead you to the library, object file or other item you might be missing.
Just for the record, advapi32.lib will be needed by most Windows applications of any complexity.
you can try to use dependencywalker to see the list of dependencies for your dlls and see what it's missing.
have you entered the *.lib file in the linker options? (input --> additional dependencies"), and in addition the path to the .lib in libraries directories option?
When I am using Qt (v4.7.4) and Boost (tried v1.47 and v1.48) together in my c++ project, I get a linker error caused by a class that includes <boost\filesystem.hpp>. I just set up Qt and before the code was working without any problems.
This is error message:
...obj : error LNK2001: unresolved external symbol "private: static class std::codecvt const * & __cdecl boost::filesystem3::path::wchar_t_codecvt_facet(void)" (?wchar_t_codecvt_facet#path#filesystem3#boost##CAAAPBV?$codecvt#GDH#std##XZ)
...obj : error LNK2001: unresolved external symbol "void __cdecl boost::filesystem3::path_traits::convert(char const *,char const *,class std::basic_string,class std::allocator > &,class std::codecvt const &)" (?convert#path_traits#filesystem3#boost##YAXPBD0AAV?$basic_string#GU?$char_traits#G#std##V?$allocator#G#2##std##ABV?$codecvt#GDH#5##Z)
...obj : error LNK2001: unresolved external symbol "void __cdecl boost::filesystem3::path_traits::dispatch(class boost::filesystem3::directory_entry const &,class std::basic_string,class std::allocator > &,class std::codecvt const &)" (?dispatch#path_traits#filesystem3#boost##YAXABVdirectory_entry#23#AAV?$basic_string#GU?$char_traits#G#std##V?$allocator#G#2##std##ABV?$codecvt#GDH#6##Z)
...obj : error LNK2001: unresolved external symbol "void __cdecl boost::filesystem3::path_traits::convert(unsigned short const *,unsigned short const *,class std::basic_string,class std::allocator > &,class std::codecvt const &)" (?convert#path_traits#filesystem3#boost##YAXPBG0AAV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std##ABV?$codecvt#GDH#5##Z)
...exe : fatal error LNK1120: 4 unresolved externals
EDIT:
Here I found someone having this problem coming to this conclusion:
this really is a Qt issue. Using wchar_t as a native type you have to
recompile Qt using the same compiler switch. There even is a bug in the
tracker: https://bugreports.qt.io/browse/QTBUG-9617
In general, you will have to be very careful and do not mix wchar_t
compiler settings in your projects as they will become incompatible.
So I recompiled Qt setting /Zc:wchar_t, but it didn't show any effect. I still get the same error.
I think you are on the right track, but it sounds like your -Zc:wchar_t didn't "stick." We had to do the same thing to make Qt happy with Google Breakpad and the ICU library. We changed the /Zc:wchar_t setting in (QT_SOURCE)\mkspecs\win32-msvc2008\qmake.conf and compiled Qt from source, and after that everything works.
When you build your project that uses Qt and Boost, you should see this option in the compiler output. Something like:
cl -c -nologo -Zm200 -Zc:wchar_t ... (etc.)
If you've already build Qt without this option, you may have to do a make confclean first to ensure everything really gets rebuilt with the new settings.
It sounds like -Zc:wchar_t will be the default in Qt 5.
Using boost-1.49, Qt 4.4 and VS2005 had the same problem. Going to project properties, then setting "Configuration Properties -> C/C++ -> Language -> Treat wchar_t as Built-in Type" to "Yes" fixed the problem.
Qt probably changed the tipology of your program with regards the configuration of the runtime: consequently, the boost library you use (filesystem), that come in many configuration accessed by naming convention - connot be found.
For instance, multithread runtimes require mt somewhere in library name (I hope I remember well, but anyway see the docs where details are fully documented). This naming is fairly transparent to the programmer, due to pragmas that boost programmers appropriately used to ease the library usage under different compilers.
You should miss the non-wchar filesystem.lib. When I used Windows, I used boost Jam to interface with Visual C++ (may be that goes back to the past millenium!). I hope it's still usable.
HI I'm an internship student and my job is porting a program from linux c to visual c.
I've to use Berkeley DB and Visual C++.
after trying for a while, i get the linking error
berkeleyDB.obj : error LNK2019: unresolved external symbol "int __cdecl database_select_end(unsigned int,unsigned int,struct chunk * const,int)" (?database_select_end##YAHIIQAUchunk##H#Z) referenced in function "void __cdecl op_ds_bulk(unsigned int,unsigned int *,int)" (?op_ds_bulk##YAXIPAIH#Z)
berkeleyDB.obj : error LNK2019: unresolved external symbol "void __cdecl database_sync(void)" (?database_sync##YAXXZ) referenced in function "void __cdecl op_ds_bulk(unsigned int,unsigned int *,int)" (?op_ds_bulk##YAXIPAIH#Z)
berkeleyDB.obj : error LNK2019: unresolved external symbol "void __cdecl database_insert_bluk(struct chunk *,int)" (?database_insert_bluk##YAXPAUchunk##H#Z) referenced in function "void __cdecl op_ds_bulk(unsigned int,unsigned int *,int)" (?op_ds_bulk##YAXIPAIH#Z)
berkeleyDB.obj : error LNK2019: unresolved external symbol "int __cdecl database_open(int,char *)" (?database_open##YAHHPAD#Z) referenced in function _main
no idea what are those,
pls help me
They're C++-mangled (or 'decorated') function names. C++ allows function overloading - multiple functions with the same name but with different parameter signatures - and so it needs to encode the parameters etc. into the function name to differentiate the multiple overloads at link time. Most likely your DB library was built as C and won't have decorated names.
Try wrapping your db.h include in an extern "C"
extern "C"
{
#include <db/db.h>
}
to tell the compiler to treat the API as C functions, not C++.
(It looks like you've got a typo in there too: database_insert_bluk not _bulk.)
Alternatively, it looks like Berkeley DB ship a C++ interface #include <db/db_cxx.h> you could use instead, although if you're porting code it may be easier to stick to the C interface. The difference is probably that the Linux code you're porting was compiled as C whereas here you're compiling it as C++.
From the other comment you've posted: if your problem is that you're actually not linking in Berkeley DB at all then you'll need to go into project settings (right-click on the project name), the C++ link tab, and then add the .lib file to the list of libraries to link into your project. You may need to specify the path to find this too, and you should do this for both debug and release modes (the drop down at the top of the settings).
I just have a problem that I have been trying to fix for the longest time.
I have a static library project in visual c++, and I want another project to be able to link to it. Up until now, I have simply been adding a reference to the static library project, which automatically links the library.
I want to be able to link to the library using only the header files and the .lib file. However, I get a "Unresolved external symbol" error.
I thought I was doing it right - I specified the include directory, the library directory, and went into the linker input properties and provided the lib as an additional dependency.
I am able to reference other static libraries this way (like SDL), so why do I get errors when I try to reference mine?
Thanks for the help.
Is the problem that its not referencing the actual lib file, or is something within the lib itself?
These are the error messages I get:
Error 2 error LNK2019: unresolved external symbol "public: void __thiscall XEngine::XCore::XScreen::init(class XEngine::XCore::XGame &)" (?init#XScreen#XCore#XEngine##QAEXAAVXGame#23##Z) referenced in function "void __cdecl XEngine::XEngineInit(class XEngine::XCore::XScreen &,class XEngine::XCore::XGame &)" (?XEngineInit#XEngine##YAXAAVXScreen#XCore#1#AAVXGame#31##Z) C:\Users\Xander Masotto\Documents\Visual Studio 2010\Projects\Pong\Pong\source.obj Pong
Error 3 error LNK2019: unresolved external symbol "public: __thiscall XEngine::XCore::XScreen::~XScreen(void)" (??1XScreen#XCore#XEngine##QAE#XZ) referenced in function "void __cdecl XEngine::XEngineInit(class XEngine::XCore::XGame &)" (?XEngineInit#XEngine##YAXAAVXGame#XCore#1##Z) C:\Users\Xander Masotto\Documents\Visual Studio 2010\Projects\Pong\Pong\source.obj Pong
Error 4 error LNK2019: unresolved external symbol "public: __thiscall XEngine::XCore::XScreen::XScreen(void)" (??0XScreen#XCore#XEngine##QAE#XZ) referenced in function "void __cdecl XEngine::XEngineInit(class XEngine::XCore::XGame &)" (?XEngineInit#XEngine##YAXAAVXGame#XCore#1##Z) C:\Users\Xander Masotto\Documents\Visual Studio 2010\Projects\Pong\Pong\source.obj Pong
Make sure that you are exporting the functions, classes, and variables in your library that you want exposed to other applications (i.e. your dll or exe). By default they are not exposed.
The ground work to do this is typically layed out when you create the project for your library.
#ifdef TESTLIB_EXPORTS
#define TESTLIB_API __declspec(dllexport)
#else
#define TESTLIB_API __declspec(dllimport)
#endif
With the code above generated during project creation there are only two more things for me to do to expose functions,classes, or variables:
1) Make sure that I have TESTLIB_EXPORTS defined as a preprocessor. Project settings: C++/Preprocessor/PreprocessorDefinitions
2) Use the TESTLIB_API define on each function,class, or variable i want exposed:
class TESTLIB_API Order {
void doSomething();
};