I wrote a small image processing algorithm using the CImg library and bundled it in a command line application using Visual C++ Express. Everything compiled error free and ran well, until the engineer in charge of the project decided he wanted a GUI. So I went to Qt and Qt creator. The GUI functioned fine by itself, but all hell breaks loose when I move my image processing algorithm over.
mainwindow.obj : error LNK2019: unresolved external
symbol__imp__SHGetSpecialFolderPathA@16 referenced in function "char const * __cdecl
cimg_library::cimg::programfiles_path(char const * const,bool)"
(?programfiles_path@cimg@cimg_library@@YAPBDQBD_N@Z)
mainwindow.obj : error LNK2019: unresolved external symbol
__imp__EnumDisplaySettingsW@12 referenced in function "public: static int __cdecl
cimg_library::CImgDisplay::screen_width(void)"
(?screen_width@CImgDisplay@cimg_library@@SAHXZ)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__DestroyWindow@4
referenced in function "public: struct cimg_library::CImgDisplay & __thiscall
cimg_library::CImgDisplay::assign(void)"
(?assign@CImgDisplay@cimg_library@@QAEAAU12@XZ)
mainwindow.obj : error LNK2019: unresolved external symbol
__imp__ChangeDisplaySettingsW@8 referenced in function "public: void __thiscall
cimg_library::CImgDisplay::_desinit_fullscreen(void)"
(?_desinit_fullscreen@CImgDisplay@cimg_library@@QAEXXZ)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__SetWindowPos@28
referenced in function "public: struct cimg_library::CImgDisplay & __thiscall
cimg_library::CImgDisplay::resize(int,int,bool)"
(?resize@CImgDisplay@cimg_library@@QAEAAU12@HH_N@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__AdjustWindowRect@12
referenced in function "public: struct cimg_library::CImgDisplay & __thiscall
cimg_library::CImgDisplay::resize(int,int,bool)"
(?resize@CImgDisplay@cimg_library@@QAEAAU12@HH_N@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__DispatchMessageW@4
referenced in function "public: static unsigned long __stdcall
cimg_library::CImgDisplay::_events_thread(void *)"
(?_events_thread@CImgDisplay@cimg_library@@SGKPAX@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__GetMessageW@16
referenced in function "public: static unsigned long __stdcall
cimg_library::CImgDisplay::_events_thread(void *)"
(?_events_thread@CImgDisplay@cimg_library@@SGKPAX@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__SetWindowLongW@12
referenced in function "public: static unsigned long __stdcall
cimg_library::CImgDisplay::_events_thread(void *)"
(?_events_thread@CImgDisplay@cimg_library@@SGKPAX@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__GetDC@4 referenced
in function "public: static unsigned long __stdcall
cimg_library::CImgDisplay::_events_thread(void *)"
(?_events_thread@CImgDisplay@cimg_library@@SGKPAX@Z)
mainwindow.obj : error LNK2019: unresolved external symbol
__imp__SetForegroundWindow@4 referenced in function "public: static unsigned long
__stdcall cimg_library::CImgDisplay::_events_thread(void *)"
(?_events_thread@CImgDisplay@cimg_library@@SGKPAX@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__GetWindowRect@8
referenced in function "public: static unsigned long __stdcall
cimg_library::CImgDisplay::_events_thread(void *)"
(?_events_thread@CImgDisplay@cimg_library@@SGKPAX@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__CreateWindowExA@48
referenced in function "public: static unsigned long __stdcall
cimg_library::CImgDisplay::_events_thread(void *)"
(?_events_thread@CImgDisplay@cimg_library@@SGKPAX@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__DefWindowProcW@16
referenced in function "public: static long __stdcall
cimg_library::CImgDisplay::_handle_events(struct HWND__ *,unsigned int,unsigned
int,long)" (?_handle_events@CImgDisplay@cimg_library@@SGJPAUHWND__@@IIJ@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__ShowCursor@4
referenced in function "public: static long __stdcall
cimg_library::CImgDisplay::_handle_events(struct HWND__ *,unsigned int,unsigned
int,long)" (?_handle_events@CImgDisplay@cimg_library@@SGJPAUHWND__@@IIJ@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__TrackMouseEvent@4
referenced in function "public: static long __stdcall
cimg_library::CImgDisplay::_handle_events(struct HWND__ *,unsigned int,unsigned
int,long)" (?_handle_events@CImgDisplay@cimg_library@@SGJPAUHWND__@@IIJ@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__PeekMessageW@20
referenced in function "public: static long __stdcall
cimg_library::CImgDisplay::_handle_events(struct HWND__ *,unsigned int,unsigned
int,long)" (?_handle_events@CImgDisplay@cimg_library@@SGJPAUHWND__@@IIJ@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__ShowWindow@8
referenced in function "public: static long __stdcall
cimg_library::CImgDisplay::_handle_events(struct HWND__ *,unsigned int,unsigned
int,long)" (?_handle_events@CImgDisplay@cimg_library@@SGJPAUHWND__@@IIJ@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__GetWindowLongW@8
referenced in function "public: static long __stdcall
cimg_library::CImgDisplay::_handle_events(struct HWND__ *,unsigned int,unsigned
int,long)" (?_handle_events@CImgDisplay@cimg_library@@SGJPAUHWND__@@IIJ@Z)
mainwindow.obj : error LNK2019: unresolved external symbol __imp__SetDIBitsToDevice@48
referenced in function "public: struct cimg_library::CImgDisplay & __thiscall
cimg_library::CImgDisplay::paint(void)" (?paint@CImgDisplay@cimg_library@@QAEAAU12@XZ)
debug\final.exe : fatal error LNK1120: 20 unresolved externals
NMAKE : fatal error U1077: '"c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC
\BIN\link.EXE"' : return code '0x460'
Stop.
NMAKE : fatal error U1077: '"C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC
\BIN\nmake.exe"' : return code '0x2'
Stop.
My problem now, is I have no idea why I’m having linker trouble. The CImg library is a single H file. It’s part of the project and included. I know Qt Creator needs libraries added to the project file, but what is there to add? My library is already listed under headers.
Here is the project file.
QT += core gui
TARGET = final
TEMPLATE = app
SOURCES += main.cpp\
mainwindow.cpp
HEADERS += mainwindow.h \
C:/includes/CImg.h
FORMS += mainwindow.ui
INCLUDEPATH += C:\includes\
Thanks for the assistance, I’m primarily an embedded systems programmer, and working out of my C and assembly element is getting very frustrating.
You need to link the Cimg library to you GUI program. Add the library in your .pro file.