Plugin compiler error: undefined reference

[faldzip]

app.pro

TARGET = test
TEMPLATE = app
CONFIG += debug
SOURCES += main.cpp
LIBS += E:/documents/test/app/lib/ui.dll # I realized this is the correct syntax on Windows
INCLUDEPATH += ../ui

TARGET = test
TEMPLATE = app
CONFIG += debug
SOURCES += main.cpp
LIBS += E:/documents/test/app/lib/ui.dll # I realized this is the correct syntax on Windows
INCLUDEPATH += ../ui

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I don't think so. Do you have ui.lib file generated with ui.dll. I'm not sure if DESTDIR works with it so check in debug folder. This ui.lib is the right file to link with while compiling and ui.dll it the right file to link with in runtime. And the previous syntax was okay - I use it on both - Windows and Linux.

main.cpp

// Since this is a library, I think I should use it just like QtGui and so on, so I include necessary head files and create an instance as usual
#include <QtGui/QApplication>
#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow win;
    win.show();
    return a.exec();
}

// Since this is a library, I think I should use it just like QtGui and so on, so I include necessary head files and create an instance as usual
#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow win;
    win.show();
    return a.exec();
}

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That's correct.

ui.pro

# also I should edit this file in order to generate a library instead of a plugin
TARGET = ui
TEMPLATE = lib
DEFINES += UI_LIBRARY
CONFIG += debug
SOURCES += mainwindow.cpp
HEADERS += mainwindow.h \
    ui_global.h
FORMS += mainwindow.ui
DESTDIR = ../app/lib

# also I should edit this file in order to generate a library instead of a plugin
TARGET = ui
TEMPLATE = lib
DEFINES += UI_LIBRARY
CONFIG += debug
SOURCES += mainwindow.cpp
HEADERS += mainwindow.h \
    ui_global.h
FORMS += mainwindow.ui
DESTDIR = ../app/lib

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This file looks okay now (for library).

mainwindow.h

// OK, this is almost what QtCreator generated for me, I only added show() function in order to let Qt export this function, am I right?

// OK, this is almost what QtCreator generated for me, I only added show() function in order to let Qt export this function, am I right?

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No, it is already exported in QtGui.dll as it is part of QWidget class.

OK, when I recompile this project, there is nothing wrong.

Are you sure? You are qmaking and building test.pro or app.pro?
Open VS command prompt, go to the app dir and run:

qmake && nmake

qmake && nmake

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and see what you get.

But I could not run it. It says that "E:\documents\test\app\debug\test.exe exited with code -1073741819" although I have copied ui.dll to the same directory of test.exe.

Use Dependency Walker to check library dependencies of your app.exe. And did you try also running it from outside of QtCreator just by double clicking test.exe?

[FinderCheng]

I don't think so. Do you have ui.lib file generated with ui.dll. I'm not sure if DESTDIR works with it so check in debug folder. This ui.lib is the right file to link with while compiling and ui.dll it the right file to link with in runtime. And the previous syntax was okay - I use it on both - Windows and Linux.

Sorry, I check both DESTDIR and debug folders and there is no such file called ui.lib.

Are you sure? You are qmaking and building test.pro or app.pro?

Yes, I rebuild project with test.pro and app.pro each time and there is no error.

Open VS command prompt, go to the app dir and run:

qmake && nmake

qmake && nmake

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and see what you get.

I'm sorry but I have no VS compiler. So I open app.pro as a separate project and build it, nothing wrong here.

Use Dependency Walker to check library dependencies of your app.exe. And did you try also running it from outside of QtCreator just by double clicking test.exe?

I have a little trouble with Dependency Walker. What results should I looking for? I checked test.exe(not app.exe, TARGET = test in app.pro) and its library contains ui.dll. And I tried to open test.exe outside QtCreator, no window opened...