compilation error

[jjbabu]

after installing qt,i just for checking i compiled

#include <QApplication>
#include <QLabel>
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QLabel *label = new QLabel("Hello Qt!");
    label->show();
    return app.exec();
}

#include <QApplication>
#include <QLabel>
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QLabel *label = new QLabel("Hello Qt!");
    label->show();
    return app.exec();
}

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but compiler showing below error:

hello.cpp:9:2: warning: no newline at end of file
g++ -enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-rel
oc -mthreads -Wl -Wl,-subsystem,windows -o debug\hello.exe tmp/obj/debug_shared/
hello.o -L"c:\Qt\4.4.3\lib" -L"c:\Program Files\SQLXML 4.0\bin\" -L"c:\Qt\4.4.3
\lib" -lmingw32 -lqtmaind -lQtGuid4 -lQtCored4
tmp/obj/debug_shared/hello.o(.text+0x158): In function `Z5qMainiPPc':
C:/Qt/4.4.3/hello/hello.cpp:5: undefined reference to `_imp___ZN12QApplicationC1
ERiPPci'
tmp/obj/debug_shared/hello.o(.text+0x1ec):C:/Qt/4.4.3/hello/hello.cpp:6: undefin
ed reference to `_imp___ZN6QLabelC1ERK7QStringP7QWidget6QFlagsIN2Q t10WindowTypeE
E'
tmp/obj/debug_shared/hello.o(.text+0x2b2):C:/Qt/4.4.3/hello/hello.cpp:8: undefin
ed reference to `_imp___ZN12QApplication4execEv'
tmp/obj/debug_shared/hello.o(.text+0x2cf):C:/Qt/4.4.3/hello/hello.cpp:8: undefin
ed reference to `QApplication::~QApplication()'
tmp/obj/debug_shared/hello.o(.text+0x2fe):C:/Qt/4.4.3/hello/hello.cpp:8: undefin
ed reference to `QApplication::~QApplication()'
tmp/obj/debug_shared/hello.o(.text$_ZN7QStringD1Ev[QString::~QString()]+0x20): I
n function `ZSt3minIjERKT_S2_S2_':
C:/Qt/4.4.3/hello/../include/QtCore/../../src/corelib/tools/qstring.h: undefined
reference to `_imp___ZN7QString4freeEPNS_4DataE'
tmp/obj/debug_shared/hello.o(.text$_ZN7QStringC1EPKc[QString::QString(char const
*)]+0x19):C:/Qt/4.4.3/hello/../include/QtCore/../../src/corelib/tools/qstring.h:
undefined reference to `_imp___ZN7QString16fromAscii_helperEPKci'
/mingw/lib/libmingw32.a(main.o)(.text+0x106):main.c: undefined reference to `Win
Main@16'
collect2: ld returned 1 exit status
mingw32-make[1]: *** [debug\hello.exe] Error 1
mingw32-make[1]: Leaving directory `C:/Qt/4.4.3/hello'
mingw32-make: *** [debug-all] Error 2

what does it mean?can anyone help me....
thanks in advance.

[talk2amulya]

what kind of application did you create? Qt Console or Qt Gui?

[jjbabu]

QtGui only.
i just want to check whether "hello qt" label will be displayed or not.

[lyuts]

What is in your .pro file?

[jjbabu]

this is my .pro file:

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

# Input
SOURCES += hello.cpp

[lyuts]

Try adding QT += gui to you .pro file.

[talk2amulya]

u havent included QtGui..QApplication and QLabel are both part of it

[jjbabu]

I tried by adding "QT += gui" to my .pro file and also i included "#include <QtGui>" in my .cpp file,but the result is same.

i have visual studio 2005 in my system,but i have not integrated my qt with visual studio.
is VS2005 cause for this errors?

previously i installed qt with minGW on my windows system with out having VS2005.at that time examples of qt are compiled fine,but know i am facing this problem.

what is the reason behind this anyone can explain?
thanks...

[spirit]

Try adding QT += gui to you .pro file.

this flag included by default, from docs

By default, QT contains both core and gui, ensuring that standard GUI applications can be built without further configuration.

[spirit]

I tried by adding "QT += gui" to my .pro file and also i included "#include <QtGui>" in my .cpp file,but the result is same.

i have visual studio 2005 in my system,but i have not integrated my qt with visual studio.
is VS2005 cause for this errors?

previously i installed qt with minGW on my windows system with out having VS2005.at that time examples of qt are compiled fine,but know i am facing this problem.

what is the reason behind this anyone can explain?
thanks...

did you build Qt for VS2005?

[lyuts]

this flag included by default, from docs

Yeah, that's right until a user modifies qmake.conf. Someone might prefer to change the default settings.

[jjbabu]

of course by default that will be added to our project,but what are the reasons behind those errors.i tried so many ways,but i couldn't rectify those errors.not even examples in the qt are running.

[spirit]

ask you again: did you build Qt for VS2005?
do you use only minGW or VS2005 too?

[jjbabu]

i have not build qt with VS2005.i am directly using qt.

[spirit]

so, why did you ask about VS? I thought that you have Qt built for MinGW and you try to use this Qt version with VS.
did you try to make mingw32-make clean & qmake & mingw32-make?

[jjbabu]

Spirit let me explain clearly what is my problem:

STEP1:there is no qt on my machine,it is having VS2005 and .NET framework.

STEP2:Now i want to develope QT applications,For that reason i downloaded QT version "qt-win-opensource-4.4.3-mingw" and installed along with MINGW in my "C" directory.

STEP3:i created folder in "C:\Qt\4.4.3" with the name hello and i placed "hello.cpp" file

STEP4:using "QT4.4.3 command prompt" i compiled my application,for compilation i used
qmake -project ; qmake ;make.

at this point of time i got errors of unreferensed which are montion in my 1st post.

where i did wrong? please help me...

[spirit]

looks like you did right steps.
can you show us what returns this command echo %QTDIR% in "QT4.4.3 command prompt".

[jjbabu]

it is showing like below:

C:\Qt\4.4.3

[jjbabu]

are u interested to see any of my system variables and user variables?

[spirit]

I don't know what to say you, looks like you did everything right.
I don't know what to suggest you except as remove this Qt installation at all, reinstall it and try to compile an example again.