Thread: error LNK2019: unresolved external symbol __imp__GetKeyState@4

Hi, I have written a C++ program, which I have previously compiled with MinGW. However, due to tricky circumstances (MinGW doesn't handle Boost very well apparently), I had to change to Visual Studio. The project compiles perfectly, except from one row, which calls the function GetKeyState located in windows.h. If I include that line in my code, I get the following compilation result:

Code:

------ Build started: Project: user_interface, Configuration: Release Win32 ------
Performing Makefile project actions
QFileInfo::absolutePath: Constructed with empty filename
Microsoft (R) Program Maintenance Utility Version 9.00.21022.08
Copyright (C) Microsoft Corporation.  All rights reserved.
 "c:\Program Files\Microsoft Visual Studio 9.0\VC\bin\nmake.exe" -f Makefile.Debug
Microsoft (R) Program Maintenance Utility Version 9.00.21022.08
Copyright (C) Microsoft Corporation.  All rights reserved.
 cl -c -nologo -Zm200 -Zc:wchar_t- -Zi -MDd -GR -EHsc -W3 -w34100 -w34189 -DUNICODE -DWIN32 -DQT_LARGEFILE_SUPPORT -DQT_DLL -DQT_GUI_LIB -DQT_CORE_LIB -DQT_THREAD_SUPPORT -I"c:\Program1\Qt\2010.02.1\qt\include\QtCore" -I"c:\Program1\Qt\2010.02.1\qt\include\QtGui" -I"c:\Program1\Qt\2010.02.1\qt\include" -I"." -I"c:\Program1\Qt\2010.02.1\qt\include\ActiveQt" -I"debug" -I"c:\Program1\Qt\2010.02.1\qt\mkspecs\default" -Fodebug\ @C:\Users\KRISTO~1\AppData\Local\Temp\nmD695.tmp
user_interface.cpp
 link /LIBPATH:"c:\Program1\Qt\2010.02.1\qt\lib" /NOLOGO /DEBUG /MANIFEST /MANIFESTFILE:"debug\user_interface.intermediate.manifest" /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /OUT:debug\user_interface.exe @C:\Users\KRISTO~1\AppData\Local\Temp\nmEAB3.tmp 
LINK : debug\user_interface.exe not found or not built by the last incremental link; performing full link
user_interface.obj : error LNK2019: unresolved external symbol __imp__GetKeyState@4 referenced in function "unsigned char __cdecl get_key_down(int)" (?get_key_down@@YAEH@Z)
debug\user_interface.exe : fatal error LNK1120: 1 unresolved externals
NMAKE : fatal error U1077: '"c:\Program Files\Microsoft Visual Studio 9.0\VC\bin\link.EXE"' : return code '0x460'
Stop.
NMAKE : fatal error U1077: '"c:\Program Files\Microsoft Visual Studio 9.0\VC\bin\nmake.exe"' : return code '0x2'
Stop.
Project : error PRJ0019: A tool returned an error code from "Performing Makefile project actions"
Build log was saved at "file://d:\Work\TSEA27_(Elektronikprojektet)\Projektet\src\user_interface_visual_studio\user_interface\Release\BuildLog.htm"
user_interface - 5 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

"user_interface.obj : error LNK2019: unresolved external symbol __imp__GetKeyState@4 referenced in function "unsigned char __cdecl get_key_down(int)" (?get_key_down@@YAEH@Z)"
This is probably a beginner problem, but what is causing it and how do I solve it? If I have to include some library to make it work, how do I do that and where is the library located?

Adding the path to the library to the dependency path didn't make any difference.

Normal Win32 Console Applications that use GetKeyState can be compiled, and they could before I added the path to the dependency paths to (which I found out).

Makefile Projects that uses GetKeyState on the other hand, can't be compiled, there the compiler will give an error corresponding to: "main.obj : error LNK2019: unresolved external symbol __imp__GetKeyState@4 referenced in function _main". Why I don't know.

My program is a Makefile Project, and I can't compile it, although I think I should be able to.

I have never worked with makefiles, but MSDN says it's in user32.lib. So you can't go to C/C++ -> Linker -> Input -> and enter user32.lib?

The problem has already been resolved. No, there is no such thing in VS Makefile Projects, there you simply have to add the libraries and the dependency paths directly into your makefile.

The thing that caused the problem in my case, was that I was building a Qt project, and let qt generate the makefiles for me from a .pro file (qt project file), with a program called qmake. The generated makefiles then contained something that visual studio didn't like, or at least treated differently than MinGW. The solution to the problem was to change in my .pro file, and add "LIBS += User32.Lib", in order to tell qmake to generate the appropriate makefiles.

-Kristofer