problem in qt hello world programme

[u04f061]

i am new user of qt and i am running ubuntu dapper linux.i got this hello world programe from trolltech official site. i could not run this programe. i got an error.here it is

#include <qapplication.h>
#include <qpushbutton.h>g++ -c -pipe -g -Wall -W -D_REENTRANT -DQT_GUI_LIB -DQT_CORE_LIB -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I. -I. -o main.o main.cpp
main.cpp: In function ‘int main(int, char**)’:
main.cpp:12: error: ‘class QApplication’ has no member named ‘setMainWidget’
make: *** [main.o] Error 1

int main( int argc, char **argv )
{
    QApplication a( argc, argv );
 
    QPushButton hello( "Hello world!", 0 );
    hello.resize( 100, 30 );
 
    a.setMainWidget( &hello );
    hello.show();
    return a.exec();
}

int main( int argc, char **argv )
{
    QApplication a( argc, argv );

    QPushButton hello( "Hello world!", 0 );
    hello.resize( 100, 30 );

    a.setMainWidget( &hello );
    hello.show();
    return a.exec();
}

To copy to clipboard, switch view to plain text mode 

then i made .pro file with name main.pro using qmake -project
here is this file

################################################## ####################
# Automatically generated by qmake (2.00a) Wed Mar 7 15:54:23 2007
################################################## ####################

TEMPLATE = app
TARGET +=
DEPENDPATH += .
INCLUDEPATH += .

# Input
SOURCES += main.cpp


then i made make file using qmake
then i ran the command make. after short time it gave the following error

g++ -c -pipe -g -Wall -W -D_REENTRANT -DQT_GUI_LIB -DQT_CORE_LIB -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I. -I. -o main.o main.cpp
main.cpp: In function ‘int main(int, char**)’:
main.cpp:12: error: ‘class QApplication’ has no member named ‘setMainWidget’
make: *** [main.o] Error 1

[jpn]

Looks like you have installed Qt4 but are trying to compile an old Hello World for Qt3. Try Hello World for Qt4.

[patrik08]

i am new user of qt and i am running ubuntu dapper linux.i got this hello world programe from trolltech official site. i could not run this programe. i got an error.here it is
int main( int argc, char **argv )
{
QApplication a( argc, argv );

QPushButton hello( "Hello world!", 0 );
hello.resize( 100, 30 );


hello.show();
return a.exec();
}

ror 1

QApplication is not a widget remove line a.setMainWidget( &hello ); or insert a widged..

#include <QApplication>
#include <QLabel>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QLabel label("Hallo Welt!");
    label.show();
 
    return a.exec();
}

#include <QApplication>
#include <QLabel>

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

    QLabel label("Hallo Welt!");
    label.show();

    return a.exec();
}

To copy to clipboard, switch view to plain text mode 

or ....

#include <QApplication>
#include <QPushButton>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QPushButton button("Beenden");
    button.show();
 
    QObject::connect(&button, SIGNAL(clicked()),
                     &a, SLOT(quit()));
 
    return a.exec();
}

#include <QApplication>
#include <QPushButton>

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

    QPushButton button("Beenden");
    button.show();

    QObject::connect(&button, SIGNAL(clicked()),
                     &a, SLOT(quit()));

    return a.exec();
}

To copy to clipboard, switch view to plain text mode 

or... ++ QWidget window;

#include <QApplication>
#include <QVBoxLayout>
#include <QLabel>
#include <QSpinBox>
#include <QSlider>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QWidget window;
 
    QVBoxLayout* mainLayout = new QVBoxLayout(&window);
    QLabel* label = new QLabel("0");
    QSpinBox* spinBox = new QSpinBox;
    QSlider* slider = new QSlider(Qt::Horizontal);
 
    mainLayout->addWidget(label);
    mainLayout->addWidget(spinBox);
    mainLayout->addWidget(slider);
 
    QObject::connect(spinBox, SIGNAL(valueChanged(int)),
                     label, SLOT(setNum(int)));
    QObject::connect(spinBox, SIGNAL(valueChanged(int)),
                     slider, SLOT(setValue(int)));
    QObject::connect(slider, SIGNAL(valueChanged(int)),
                     label, SLOT(setNum(int)));
    QObject::connect(slider, SIGNAL(valueChanged(int)),
                     spinBox, SLOT(setValue(int)));
 
    window.show();
 
    return a.exec();
}

#include <QApplication>
#include <QVBoxLayout>
#include <QLabel>
#include <QSpinBox>
#include <QSlider>

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

    QWidget window;

    QVBoxLayout* mainLayout = new QVBoxLayout(&window);
    QLabel* label = new QLabel("0");
    QSpinBox* spinBox = new QSpinBox;
    QSlider* slider = new QSlider(Qt::Horizontal);

    mainLayout->addWidget(label);
    mainLayout->addWidget(spinBox);
    mainLayout->addWidget(slider);

    QObject::connect(spinBox, SIGNAL(valueChanged(int)),
                     label, SLOT(setNum(int)));
    QObject::connect(spinBox, SIGNAL(valueChanged(int)),
                     slider, SLOT(setValue(int)));
    QObject::connect(slider, SIGNAL(valueChanged(int)),
                     label, SLOT(setNum(int)));
    QObject::connect(slider, SIGNAL(valueChanged(int)),
                     spinBox, SLOT(setValue(int)));

    window.show();

    return a.exec();
}

To copy to clipboard, switch view to plain text mode 

[u04f061]

still having a problem. following error occurs

g++ -c -pipe -g -Wall -W -D_REENTRANT -DQT_GUI_LIB -DQT_CORE_LIB -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I. -I. -o qt4h.o qt4h.cpp
g++ -o qt4h qt4h.o -L/usr/lib -lQtGui_debug -lQtCore_debug -lpthread
/usr/bin/ld: cannot find -lQtGui_debug
collect2: ld returned 1 exit status
make: *** [qt4h] Error 1

i think i am missing some package.i am installing libqt4-debug from repository. its size is 51MB.am i right or there is some other faylt?

[patrik08]

still having a problem. following error occurs
i think i am missing some package.i am installing libqt4-debug from repository. its size is 51MB.am i right or there is some other faylt?

How you installed qt only static && release .... or you get the new Ubuntu Feisy ready to use package qt4.2 ?

[u04f061]

How you installed qt only static && release .... or you get the new Ubuntu Feisy ready to use package qt4.2 ?

i installed qt from repository. its download size was 4Mb and install size was 51Mb. the package names i don't remember

[jpn]

So, the problem was solved? (Yes, you were missing the debug libs)