I have created simple test project that uses QT3 gui. The main function is as follows:
int main(int argc, char** argv)
{
QApplication a(atgc, argv);
MainWindow *w = new MainWindow;
w->show();
a.setMainWidget(w);
a.exec();
if(w) delete w;
return 0;
}
When I compile it like this:
qmake
make
it is ok (the used compiler is g++-2.95.4). But when I do this:
qmake
make CXX=g++-3.3.6 LINK=g++-3.3.6
I get tons of link errors like this:
.obj/main.o(.text+0x27): In function `main':
: undefined reference to `QApplication::QApplication[in-charge](int&, char**)'
.obj/main.o(.text+0x66): In function `main':
: undefined reference to `QApplication::setMainWidget(QWidget*)'
.obj/main.o(.text+0x6e): In function `main':
: undefined reference to `QApplication::exec()'
It seems like it has not linked qt libraries properly. Is there any idea how to build project using any other compiler? I am using linux RedHat.
Related
I am relatively new to Qt and was going through many tutorials. Everything was fine. All scripts compiled and ran.
Then, at some point, I am getting the error for even a new Qt widget application created with Qt Creator 4.3.1:
C:\ \Documents\111\main.cpp:-1: In function 'int qMain(int, char**)':
C:\ \Documents\111\main.cpp:6: error: variable 'QApplication a' has initializer but incomplete type
QApplication a(argc, argv);
^
C:\ \Documents\111\main.cpp:11: warning: control reaches end of non-void function [-Wreturn-type]
}
^
I am not sure what happened, yet seems like some setups were messed up.
QApplication is included, and not missing in the script.
111.pro
# Project created by QtCreator 2018-02-23T01:36:28
QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = 111
TEMPLATE = app
DEFINES += QT_DEPRECATED_WARNINGS
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0
SOURCES += \
main.cpp \
mainwindow.cpp
HEADERS += \
mainwindow.h
FORMS += \
mainwindow.ui
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
mainview.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
It seems to me that this issue appeared after trying to run qt5.6_src.zip examples from https://en.ids-imaging.com/open-source.html.
Without completed code, I guess you need to add #include <QApplication> to main.cpp
The error message told you what is missing.
According to Qt's docs, the constructor's signature is QApplication(int &argc, char **argv).
Therefore, if you inherit from QApplication then the subclass's constructor must pass argc by reference. From your description, it appears that the constructor of your subclass is actually passing argc by value (i.e., int qMain(int, char**) ). That will cause some problems.
The issue is fixed by deleting the Qt folder and QtCreator folder in the <drive>:\Users\<username>\AppData\Roaming\QtProject and <drive>:\Users\<username>\AppData\Roaming\Qt. It stored incorrect settings, which I somehow setup by running open source scripts. For more information visit Where does QtCreator save its settings?.
I am trying to use Taglib with Qt5.7. But my programm crashes:
The GDB process terminated unexpectedly (exit code 0).
Cannot continue debugged process: The program is not being run.
During startup program exited with code 0xc0000135
There did not seem to be any error messages while building Taglib.
*.pro file
QT += core
QT -= gui
CONFIG += c++11
TARGET = untitled2
CONFIG += console
CONFIG -= app_bundle
TEMPLATE = app
SOURCES += main.cpp
TAGLIBDIR = $$quote(D:/D/Programmieren/Libraries/taglib)
INCLUDEPATH += $$quote( $${TAGLIBDIR}/include )
LIBS += -L$$quote($${TAGLIBDIR}/lib) -ltag
main.cpp
#include <QCoreApplication>
#include <taglib/tag.h>
#include <taglib/fileref.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
TagLib::FileRef ref("D:/D/Media/Musik/Disturbed/The Sickness/Disturbed - Stupify.mp3");
return a.exec();
}
Edit:
I created Taglib-buildfiles using CMake-GUI and native MinGW-Installation since I did not manage to create them using Qt. My OS is Windows 10 x64 Education and I use Qt-Creator. I downloaded the latest Taglib-Release (1.11.1)
Why I cant create buildfiles using CMake:
First some *dll-files where missing, i coud solve that by just copying the ones from native MinGW-Installation to QT-MinGW.
Second I could not find any of the *exe-files desired by CMake so i could not change the path from native MinGW-Installation.
After rebuilding Taglib in debugmode I get this errors:
main.cpp:10: error: undefined reference to `_imp___ZN6TagLib8FileNameC1EPKc'
main.cpp:10: error: undefined reference to `_imp___ZN6TagLib7FileRefC1ENS_8FileNameEbNS_15AudioProperties9ReadStyleE'
main.cpp:11: error: undefined reference to `_imp___ZNK6TagLib7FileRef3tagEv'
main.cpp:11: error: undefined reference to `_imp___ZNK6TagLib6String9toCStringEb'
main.cpp:11: error: undefined reference to `_imp___ZN6TagLib6StringD1Ev'
main.cpp:10: error: undefined reference to `_imp___ZN6TagLib7FileRefD1Ev'
main.cpp:11: error: undefined reference to `_imp___ZN6TagLib6StringD1Ev'
main.cpp:10: error: undefined reference to `_imp___ZN6TagLib7FileRefD1Ev'
collect2.exe:-1: error: error: ld returned 1 exit status
Solved it by using new version (5.8 instead of 5.7) of Qt.
hi i'm just trying to compile an easy project in qt
#include <QApplication>
#include <QPushButton>
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QPushButton bouton("Salut les Zéros, la forme ?");
bouton.show();
return app.exec();
}
but i have this error : /home/eid/test/easyprojet/main.cpp:1: error: QApplication: No such file or directory
can anyone help me ?
sorry for my english
In Qt5, it resides in , while in Qt4 it was .
In Qt5 you need to add QT += widgets to your .pro file.
It may be also because the project is not in the workspace of QT creator.
It happened with me before.
so,try to put the project in the workspace .
I've got a relatively simple Qt 5.0 project that uses CMake 2.8.9:
CMakeLists.txt:
cmake_minimum_required(VERSION 2.8.9)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
project(hello-world)
find_package(Qt5Widgets REQUIRED)
qt5_wrap_ui(hello-world_UI MainWindow.ui)
add_executable(hello-world MainWindow.cpp main.cpp ${hello-world_UI})
qt5_use_modules(hello-world Widgets)
MainWindow.h:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow();
virtual ~MainWindow();
private:
Ui::MainWindow * const ui;
};
#endif // CMAINWINDOW_H
MainWindow.cpp:
#include "MainWindow.h"
#include "ui_MainWindow.h"
MainWindow::MainWindow()
: ui(new Ui::MainWindow)
{
}
MainWindow::~MainWindow()
{
delete ui;
}
main.cpp:
#include <QApplication>
#include "MainWindow.h"
int main(int argc, char * argv[])
{
QApplication app(argc, argv);
MainWindow win;
win.show();
return app.exec();
}
The project also includes a .ui file created with Qt Creator 2.6.1 (MainWindow.ui).
When I attempt to build the file with g++ on Linux, I receive the following errors:
CMakeFiles/hello-world.dir/MainWindow.cpp.o: In function `MainWindow::MainWindow()':
MainWindow.cpp:(.text+0x3b): undefined reference to `vtable for MainWindow'
MainWindow.cpp:(.text+0x4d): undefined reference to `vtable for MainWindow'
CMakeFiles/hello-world.dir/MainWindow.cpp.o: In function `MainWindow::~MainWindow()':
MainWindow.cpp:(.text+0xaf): undefined reference to `vtable for MainWindow'
MainWindow.cpp:(.text+0xc1): undefined reference to `vtable for MainWindow'
collect2: error: ld returned 1 exit status
What could possibly be causing this sort of error? I recently switched to CMake from qmake and I never remember running into this much trouble getting a trivial example to compile. What am I doing wrong?
Edit: here is the command being used to link everything:
/usr/bin/c++ CMakeFiles/hello-world.dir/MainWindow.cpp.o
CMakeFiles/hello-world.dir/main.cpp.o -o hello-world -rdynamic
/usr/local/Qt-5.0.0/lib/libQt5Widgets.so.5.0.0
/usr/local/Qt-5.0.0/lib/libQt5Gui.so.5.0.0
/usr/local/Qt-5.0.0/lib/libQt5Core.so.5.0.0
-Wl,-rpath,/usr/local/Qt-5.0.0/lib
Turns out I forgot:
set(CMAKE_AUTOMOC ON)
At the top of the CMakeLists.txt file.
I struggled with this for a long time using all the hints published here:
http://doc.qt.io/qt-5/cmake-manual.html
And here
https://www.kdab.com/using-cmake-with-qt-5/
What I had to do was specify things in the right order. For example, the following is the top of my CMakeLists.txt. Note that the two CMAKE set directives come before add_executable. Once I did this, I was able to link without undefined symbols and vtable references. I just thought I'd post this for the benefit of others.
cmake_minimum_required (VERSION 2.8)
set (CMAKE_AUTOMOC ON)
set (CMAKE_INCLUDE_CURRENT_DIR ON)
add_executable(FHSpectrumSensor wideband_seq_spectrum_sensor.cpp sensor.cpp gui.cpp ${gui_SRC})
Later in the CMakeLists.txt I have the following:
find_package(Qt5Widgets REQUIRED)
find_package(Qt5Charts REQUIRED)
find_package(Qt5Core REQUIRED)
qt5_use_modules(FHSpectrumSensor Widgets Charts)
qt5_wrap_cpp(gui_SRC gui.h gui.cpp)
That did the trick.
I also ran into this problem yesterday and the above mentioned answers did't help. I already used set (CMAKE_AUTOMOC ON) and also qt5_wrap_cpp.
I tried to remember what I did, because I had a working version but it stopped working after "some" changes. I finally remembered that I tried to split the include files into a separate directory hierarchy. After reverting that and putting the include files back into the CMakeLists.txt it worked again. I sure don't know why, and I would like to know what went wrong, but I settled now for keeping the includes near the cpp files.
set(SOURCES
buffer.h
ITVSet.h
MainWindow.h
MainWindow.cpp
TVSet.h
TVSet.cpp
)
I've tried to compile the following code using Qt(4.6.3) + MinGW:
#include <QtCore/QCoreApplication>
#include <exception>
int main(int argc, char *argv[])
{
throw std::runtime_error("");
QCoreApplication a(argc, argv);
return a.exec();
}
... and got this error:
..\untitled11\main.cpp:6: error: 'runtime_error' is not a member of 'std'
Project created from scratch(console application), the pro file:
QT += core
QT -= gui
TARGET = untitled11
CONFIG += console
CONFIG -= app_bundle
TEMPLATE = app
SOURCES += main.cpp
Tried to compile this using Qt+MSVC2008 compiler - works fine.
This is a standard exception, have no idea why is missing.
<exception> defines only the base std::exceptionclass; if you want child classes like std::runtime_error, you must include the <stdexcept> header.