I've been trying to write a small application which will work with mysql in C++. I am using MySQL server 5.1.41 and MySQL C++ connector 1.0.5. Everything compiles fine when i write console applications, but when i try to compile windows forms application exactly the same way (same libraries, same paths, same project properties) i get this errors:
Error 1 error LNK2001: unresolved external symbol "public: virtual int __clrcall sql::mysql::MySQL_Savepoint::getSavepointId(void)" (?getSavepointId#MySQL_Savepoint#mysql#sql##$$FUAMHXZ) test1.obj test1
Error 2 error LNK2001: unresolved external symbol "public: virtual class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __clrcall sql::mysql::MySQL_Savepoint::getSavepointName(void)" (?getSavepointName#MySQL_Savepoint#mysql#sql##$$FUAM?AV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std##XZ) test1.obj test1
following instructions from here, i've got this:
Undecoration of :- "?getSavepointId#MySQL_Savepoint#mysql#sql##UEAAHXZ"
is :- "public: virtual int __cdecl sql::mysql::MySQL_Savepoint::getSavepointId(void) __ptr64"
Undecoration of :- "?getSavepointName#MySQL_Savepoint#mysql#sql##UEAA?AV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std##XZ"
is :- "public: virtual class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl sql::mysql::MySQL_Savepoint::getSavepointName(void) __ptr64"
but what should i do now?
Project + Properties, General, change Common Language Runtime support to /clr from /clr:pure
Looks like an issue with calling conventions. I am not very familiar with managed C++, but this might help you.
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'm work with GCD in C++ with xdisptach, libdispatch in Visual Studio 2012 on Windows 7.
I am declaring a class with a global variable that is a dispatch queue. Other functions in the class call the queue's function. Everything compiles fine, except when i instantiate the queue in the constructor.
xdispatch::queue* dispatch_queue;
AsyncNode()
{
dispatch_queue = new xdispatch::queue(Name);
}
When dispatch_queue = new xdispatch::queue(Name); is commented out, it all compiles fine. Otherwise i get the following errors.
Error 50 error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall xdispatch::queue::~queue(void)" (__imp_??1queue#xdispatch##UAE#XZ) referenced in function "public: virtual void * __thiscall xdispatch::queue::`scalar deleting destructor'(unsigned int)" (??_Gqueue#xdispatch##UAEPAXI#Z)
Error 49 error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall xdispatch::queue::queue(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (__imp_??0queue#xdispatch##QAE#ABV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std###Z) referenced in function "public: __thiscall AsyncNode::AsyncNode(void)" (??0AsyncNode##QAE#XZ)
Error 53 error LNK2001: unresolved external symbol "public: virtual void __thiscall xdispatch::object::resume(void)" (?resume#object#xdispatch##UAEXXZ)
Error 51 error LNK2001: unresolved external symbol "public: virtual void * __thiscall xdispatch::queue::native(void)const " (?native#queue#xdispatch##UBEPAXXZ)
Error 52 error LNK2001: unresolved external symbol "public: virtual struct dispatch_queue_s * __thiscall xdispatch::queue::native_queue(void)const " (?native_queue#queue#xdispatch##UBEPAUdispatch_queue_s##XZ)
This is the main site for xdispatch, but i can't find anything in terms of a forum or help with xdispatch in particular. There are many for objective-c.... :/
http://opensource.mlba-team.de/xdispatch/docs/current/index.html
First of all, the behavior regarding deleting the "problematic" line is normal - when you're defining a pointer you're not invoking any function, and that is the reason you are not getting the "unresolved external errors".
When you're initializing the variable by calling the constructor, you then run into problems because you're trying to call a function which is not available at link time.
When working with external libraries using DLLs, you must link to the appropriate import libraries, usually supplied as "lib" files. In your case, there is a folder named "lib" in the zip package. Also, the DLLs must availble at run-time - by putting them in the folder of the executable, or adding them to the PATH environment variable.
In order to link to a library, follow these steps (taken from MSDN):
Open the project's Property Pages dialog box. For details, see Setting Visual C++ Project Properties.
Click the Linker folder.
Click the Input property page.
Modify the Additional Dependencies property.
Is there any way I can have the main functions for a library built in vs 2010 be accessible from a vs2005 project? The problem that I face is that I have a project in vs 2005 that needs to use the clang frontend library to parse c code. The clang library requires vs 2010 to compile.
Any light you could shed on my problem is appreciated.
Thanks,
Saketh
EDIT:
I receive the following linker errors on compilation
1>hello.lib(hello.obj) : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __int64 __thiscall std::ios_base::width(_int64)" (_imp_?width#ios_base#std##QAE_J_J#Z) referenced in function "class std::basic_ostream > & __cdecl std::operator<< >(class std::basic_ostream > &,char const *)" (??$?6U?$char_traits#D#std###std##YAAAV?$basic_ostream#DU?$char_traits#D#std###0#AAV10#PBD#Z)
1>hello.lib(hello.obj) : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __int64 __thiscall std::basic_streambuf >::sputn(char const *,_int64)" (_imp_?sputn#?$basic_streambuf#DU?$char_traits#D#std###std##QAE_JPBD_J#Z) referenced in function "class std::basic_ostream > & __cdecl std::operator<< >(class std::basic_ostream > &,char const *)" (??$?6U?$char_traits#D#std###std##YAAAV?$basic_ostream#DU?$char_traits#D#std###0#AAV10#PBD#Z)
1>hello.lib(hello.obj) : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __int64 __thiscall std::ios_base::width(void)const " (_imp?width#ios_base#std##QBE_JXZ) referenced in function "class std::basic_ostream > & __cdecl std::operator<< >(class std::basic_ostream > &,char const *)" (??$?6U?$char_traits#D#std###std##YAAAV?$basic_ostream#DU?$char_traits#D#std###0#AAV10#PBD#Z)
1>C:\Users\sakethk\Perforce\sakethk_SAKETHK_7702\source\qcom\qct\modem\uim\tools\sakethk\hello05\Debug\hello05.exe : fatal error LNK1120: 3 unresolved externals
No. Within a single module, you cannot mix objects compiled against different major versions of the CRT. This generally procludes mixing of objects compiled using different major versions of the compiler.
The correct thing to do would be to encapsulate your usage of Visual C++ 2010 within a DLL, and load that DLL from your executable compiled with Visual C++ 2005. Alternatively, upgrade your sources to use Visual C++ 2010. Visual C++ 2005 is ancient.
Your library functions should be at the lowest level here i mean that you should use C-style parameters to functions and use extern "C" to avoind compilers mangling. Here you will find good article on how to create a great library compatible with every compiler. http://chadaustin.me/cppinterface.html
I am getting a bunch of linking errors while trying to link the release version of an executable(debug version does not have the same issue). Comparing the command line for the link does not reveal any issues.
there are broadly 2 types of errors neither of which I can get a handle on.
The first kind complains about a unresolved external symbol _declspec(dllimport)
As an example:
error LNK2019: unresolved external symbol
"_declspec(dllimport)
public: __thiscall
stlpd_std::basic_string,class stlpd_std::allocator >::basic_string,class stlpd_std::allocator >(class stlpd_std::basic_string,class stlpd_std::allocator > const &)" (_imp??0?$basic_string#DV?$char_traits#D#stlpd_std##V?$allocator#D#2##stlpd_std##QAE#ABV01##Z) referenced in function "public: __thiscall Springfield::generic::runtime_error::runtime_error(class stlpd_std::basic_string,class stlpd_std::allocator > const &)" (??0runtime_error#generic#Springfield##QAE#ABV?$basic_string#DV?$char_traits#D#stlpd_std##V?$allocator#D#2##stlpd_std###Z)
for a more human readable version(replacing all the strings):
error LNK2019: unresolved external symbol
"__declspec(dllimport)
public: __thiscall
string::basic_string,class stlpd_std::allocator >(class string const &)" (_imp??0?$basic_string#DV?$char_traits#D#stlpd_std##V?$allocator#D#2##stlpd_std##QAE#ABV01##Z) referenced in function "public: __thiscall Springfield::generic::runtime_error::runtime_error(class string const &)" (??0runtime_error#generic#Springfield##QAE#ABV?$basic_string#DV?$char_traits#D#stlpd_std##V?$allocator#D#2##stlpd_std###Z
The sceond class of errors complains about
unresolved external symbol __CrtDbgReportW
I hope I can get some kind of insight in dealing with this.
From the errors it looks like you are not including the CRT as one of your linked libraries. Here is a link to the different CRT lib's offered in Visual Studio 2005. Choose the one which is most appropriate and make sure it's in the list of lib's to link against
http://msdn.microsoft.com/en-us/library/abx4dbyh(VS.80).aspx
It looks like you're either including a file that's been built using the debug settings or you're mixing runtime libraries (DLL and static).
I am using Visual C++ 2005 Express Edition and get the following linker errors:
19>mylib1.lib(mylibsource1.obj) : error LNK2019: unresolved external symbol "__declspec(dllimport) public: void __thiscall std::exception::_Raise(void)const " (__imp_?_Raise#exception#std##QBEXXZ) referenced in function "protected: static void __cdecl std::vector<class mytype,class std::allocator<class mytype> >::_Xlen(void)" (?_Xlen#?$vector#Vmytype##V?$allocator#Vmytype###std###std##KAXXZ)
19>mylib2.lib(mylibsource2.obj) : error LNK2001: unresolved external symbol "__declspec(dllimport) public: void __thiscall std::exception::_Raise(void)const " (__imp_?_Raise#exception#std##QBEXXZ)
19>mylib1.lib(mylibsource1.obj) : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall std::exception::exception(char const *,int)" (__imp_??0exception#std##QAE#PBDH#Z) referenced in function "public: __thiscall std::logic_error::logic_error(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0logic_error#std##QAE#ABV?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##1##Z)
19>mylib2.lib(mylibsource2.obj) : error LNK2001: unresolved external symbol "__declspec(dllimport) public: __thiscall std::exception::exception(char const *,int)" (__imp_??0exception#std##QAE#PBDH#Z)
I turned off exceptions in generated code, and I am using before including the vector header file:
#define _HAS_EXCEPTIONS 0
A few Google results turned up some stuff, but no "aha!" solutions that worked for me.
EDIT:
As noted "_HAS_EXCEPTIONS 0" doesn't turn off exceptions, per se. What it does is, at least in the vector header file, is call _Raise on an exception object instead of calling the C++ "throw". In my case, it can't link to the exception object's _Raise function since I am not including the correct library. What that library is, though, is not obvious.
Adding this line:
#define _STATIC_CPPLIB
before including the vector header seems to do the trick.
The third error makes it clear that #define the _HAS_EXCEPTIONS 0 does not affect . Now, might include (makes sense, sharing code might reduce the size of your executable). That would explain why you still have errors if you define it before your inclusion of . This kind of defines should be done in your project settings.
Note that _HAS_EXCEPTIONS is an unsupported feature in Visual Studio. It does not turn off exceptions as such.