I customize a slot in a class inherited class QObject. The error LNK2001 occurs.

smarter.math

Hello, everyone,

I use Qt creator 3.2.1 based on Qt 5.3.2 on windows7 64bit.
The compiler kit is Desktop Qt 5.3 MSVC2013 64bit (autodetected) using the compiler: Microsoft Visual C++ Compiler 12.0 (x86_amd64).

Here are the codes:

@
#include <QMainWindow>
#include <QApplication>
#include <QObject>
#include <QTextCodec>
#include <QDialog>

QTextCodec *codec = QTextCodec::codecForName("BIG5");

//類別宣告區
class SignalAndSlot : public QObject
{
Q_OBJECT
public slots:
void testSlot(void)
{

};

//主程式
int main(int argc, char *argv[])
{
QApplication a(argc, argv);

QMainWindow w;

SignalAndSlot *connector1 = new SignalAndSlot;

w.setWindowTitle("Title");

w.show();

return a.exec&#40;&#41;;

}
@

After building it, it returns LNK2001 error messages:

bq. C:\Qt\Tools\QtCreator\bin\jom.exe -f Makefile.Debug
cl -c -nologo -Zm200 -Zc:wchar_t -FS -Zi -MDd -GR -W3 -w34100 -w34189 -EHsc /Fddebug\qttest4.pdb -DUNICODE -DWIN32 -DWIN64 -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -DQT_OPENGL_ES_2 -DQT_OPENGL_ES_2_ANGLE -I"C:\Qt\5.3\msvc2013_64\include" -I"C:\Qt\5.3\msvc2013_64\include\QtWidgets" -I"C:\Qt\5.3\msvc2013_64\include\QtGui" -I"C:\Qt\5.3\msvc2013_64\include\QtANGLE" -I"C:\Qt\5.3\msvc2013_64\include\QtCore" -I"debug" -I"." -I"C:\Qt\5.3\msvc2013_64\mkspecs\win32-msvc2013" -Fodebug\ @C:\Users\user\AppData\Local\Temp\main.obj.5956.78.jom
main.cpp
..\qttest4\main.cpp(28) : warning C4189: 'connector1' : 已初始化區域變數，但並未參考
echo 1 /* CREATEPROCESS_MANIFEST_RESOURCE_ID / 24 / RT_MANIFEST / "debug\qttest4.exe.embed.manifest">debug\qttest4.exe_manifest.rc
if not exist debug\qttest4.exe if exist debug\qttest4.exe.embed.manifest del debug\qttest4.exe.embed.manifest
if exist debug\qttest4.exe.embed.manifest copy /Y debug\qttest4.exe.embed.manifest debug\qttest4.exe_manifest.bak
link /NOLOGO /DYNAMICBASE /NXCOMPAT /DEBUG /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='' processorArchitecture='*'" /MANIFEST /MANIFESTFILE:debug\qttest4.exe.embed.manifest /OUT:debug\qttest4.exe @C:\Users\user\AppData\Local\Temp\qttest4.exe.5956.1575.jom
main.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __cdecl SignalAndSlot::metaObject(void)const " (?metaObject@SignalAndSlot@@UEBAPEBUQMetaObject@@XZ)
main.obj : error LNK2001: unresolved external symbol "public: virtual void * __cdecl SignalAndSlot::qt_metacast(char const *)" (?qt_metacast@SignalAndSlot@@UEAAPEAXPEBD@Z)
main.obj : error LNK2001: unresolved external symbol "public: virtual int __cdecl SignalAndSlot::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@SignalAndSlot@@UEAAHW4Call@QMetaObject@@HPEAPEAX@Z)

I've checked this on the Internet. It seems running qmake and rebuilding it can solve this problem.
I tried but the problem is still there, so I am here looking for help.
If my expression makes you feeling difficult to understand, please let me know.
I'll try to express my question more clear.

Thanks for your help.

Chris Kawa

Hi, welcome to devnet.

You've put your class in a .cpp file. MOC (the Qt meta object compiler) only processes header files (for things like Q_OBJECT macros, signals , slots etc.). Put your class in proper .h/.cpp files where it belongs and it will work.

After you do, re-run qmake to make sure it picks up the changes (usually not necessary but can't hurt).

smarter.math

Thank you very much, Mr. Kawa. Problem solved!