Re: Can one compile khello.cc ?

From: Scott W (wegster_at_mindcore.net)
Date: 03/03/04

  • Next message: Warren Block: "Re: USB printer setup" 
    Date: Tue, 02 Mar 2004 19:19:10 -0500
To: Charles McManis <cmcmanis@mcmanis.com>

    Charles McManis wrote:

    >Ok, so this is now officially weird. I decided to try to compile khello.cc
    >from the KDE tutorial on my 4.8 system that has never had me attempt to
    >upgrade KDE on it.
    >
    >When I compile khello.cc, it compiles fine, when I link it I get this:
    >-----------------------------snip----------------------------------------------------------------
    >ddp% make
    >g++ -o khello -R/usr/X11R6/lib -L/usr/local/lib/kde3/ -L/usr/local/lib
    >-L/usr/X11R6/lib -lqt-mt -pthread -lkdeui -lkdecore -lXft khello.o
    >/usr/local/gnu/lib/gcc-lib/i386-unknown-freebsd4.8/3.2.3/../../../../i386-unknown-freebsd4.8/bin/ld:
    >warning: libstdc++.so.3, needed by /usr/X11R6/lib/libqt-mt.so, may conflict
    >with libstdc++.so.5
    >/usr/lib/libc.so.4: WARNING! setkey(3) not present in the system!
    >/usr/lib/libc.so.4: warning: this program uses gets(), which is unsafe.
    >/usr/lib/libc.so.4: warning: mktemp() possibly used unsafely; consider using
    >mkstemp()
    >/usr/lib/libc.so.4: WARNING! des_setkey(3) not present in the system!
    >/usr/lib/libc.so.4: WARNING! encrypt(3) not present in the system!
    >/usr/lib/libc.so.4: warning: tmpnam() possibly used unsafely; consider using
    >mkstemp()
    >/usr/lib/libc.so.4: warning: this program uses f_prealloc(), which is not
    >recommended.
    >/usr/lib/libc.so.4: WARNING! des_cipher(3) not present in the system!
    >/usr/lib/libc.so.4: warning: tempnam() possibly used unsafely; consider using
    >mkstemp()
    >khello.o(.text+0x2b): In function `main':
    >: undefined reference to `QCString::QCString[in-charge](char const*)'
    >khello.o(.text+0x48): In function `main':
    >: undefined reference to `KApplication::KApplication[in-charge](int&, char**,
    >QCString const&, bool, bool)'
    >khello.o(.text+0x68): In function `main':
    >: undefined reference to `QCString::~QCString [in-charge]()'
    >khello.o(.text+0x8e): In function `main':
    >: undefined reference to `QCString::~QCString [in-charge]()'
    >khello.o(.text+0xc2): In function `main':
    >: undefined reference to `KMainWindow::KMainWindow[in-charge](QWidget*, char
    >const*, unsigned)'
    >khello.o(.text+0x16e): In function `main':
    >: undefined reference to `QApplication::setMainWidget(QWidget*)'
    >khello.o(.text+0x19d): In function `main':
    >: undefined reference to `QApplication::exec()'
    >khello.o(.text+0x1b1): In function `main':
    >: undefined reference to `KApplication::~KApplication [in-charge]()'
    >khello.o(.text+0x1d7): In function `main':
    >: undefined reference to `KApplication::~KApplication [in-charge]()'
    >collect2: ld returned 1 exit status
    >make: *** [khello] Error 1
    >ddp%
    >-----------------------------------------------------------------------------------------
    >So what am I missing?
    >
    >--Chuck
    >_______________________________________________
    >freebsd-questions@freebsd.org mailing list
    >http://lists.freebsd.org/mailman/listinfo/freebsd-questions
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    >
    >
    >
    If you have a pointer to the KDE tutorial/code you're using, may be of
    more help, but here's a quick 'khello' program, step by step:

    [wegster@db KDETutorial]$ cat main.cc
    #include <qapplication.h>
    #include <qpushbutton.h>

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

        QPushButton *hello=new QPushButton( "Hello world!", 0 );
        hello->resize(200, 30 );

        QObject::connect(hello,
                            SIGNAL(clicked()),
                            &app,
                            SLOT(quit()) );

        app.setMainWidget(hello);
        hello->show();

        return app.exec();
    }

    wegster@db KDETutorial]$ g++ main.cc

    main.cc:1:26: qapplication.h: No such file or directory
    main.cc:2:25: qpushbutton.h: No such file or directory
    main.cc: In function `int main(int, char**)':
    main.cc:7: `QApplication' undeclared (first use this function)
    main.cc:7: (Each undeclared identifier is reported only once for each
    function
       it appears in.)
    main.cc:7: syntax error before `(' token
    main.cc:9: `QPushButton' undeclared (first use this function)
    main.cc:9: `hello' undeclared (first use this function)
    main.cc:9: syntax error before `(' token
    main.cc:12: `QObject' undeclared (first use this function)
    main.cc:12: syntax error before `::' token
    main.cc:17: `app' undeclared (first use this function)

    We're missing the header location in our include path (because we didn't
    specify one), so let's find it:

    [wegster@db KDETutorial]$ locate qapplication.h
    /usr/share/doc/qt-devel-3.1.2/html/qapplication.html
    /usr/lib/qt-3.1/include/qapplication.h

    The latter is the one we need, so feed the path as an include path to
    g++ via the -I switch:

    [wegster@db KDETutorial]$ g++ main.cc -I /usr/lib/qt-3.1/include
    /tmp/ccC2zAn3.o(.text+0x23): In function `main':
    : undefined reference to `QApplication::QApplication[in-charge](int&,
    char**)'
    /tmp/ccC2zAn3.o(.text+0x52): In function `main':
    : undefined reference to `QString::QString[in-charge](char const*)'
    /tmp/ccC2zAn3.o(.text+0x61): In function `main':
    : undefined reference to `QPushButton::QPushButton[in-charge](QString
    const&, QWidget*, char const*)'
    /tmp/ccC2zAn3.o(.text+0x12c): In function `main':
    : undefined reference to `QObject::connect(QObject const*, char const*,
    QObject const*, char const*)'
    /tmp/ccC2zAn3.o(.text+0x13e): In function `main':
    : undefined reference to `QApplication::setMainWidget(QWidget*)'
    /tmp/ccC2zAn3.o(.text+0x164): In function `main':
    : undefined reference to `QApplication::exec()'
    /tmp/ccC2zAn3.o(.text+0x175): In function `main':
    : undefined reference to `QApplication::~QApplication [in-charge]()'
    /tmp/ccC2zAn3.o(.text+0x195): In function `main':
    : undefined reference to `QApplication::~QApplication [in-charge]()'
    /tmp/ccC2zAn3.o(.gnu.linkonce.t._ZN7QStringD1Ev+0x21): In function
    `QString::~QString [in-charge]()':
    : undefined reference to `QString::shared_null'
    /tmp/ccC2zAn3.o(.gnu.linkonce.t._ZN7QStringD1Ev+0x30): In function
    `QString::~QString [in-charge]()':
    : undefined reference to `QStringData::deleteSelf()'
    collect2: ld returned 1 exit status

    Looks like what you've got, which isn't surprising- I'll bet we can
    compile to an object file only however, let's test using -c for 'compile
    but don't link' to g++:

    [wegster@db KDETutorial]$ g++ -c main.cc -I /usr/lib/qt-3.1/include
    [wegster@db KDETutorial]$ ls -l main.*
    -rw-rw-r-- 1 wegster wegster 380 Mar 2 19:05 main.cc
    -rw-rw-r-- 1 wegster wegster 2816 Mar 2 19:13 main.o

    Yep, that works. But to get a running executable, you need to resolve
    library dependencies, in this case likely the QT library...let's find it
    first:

    [wegster@db KDETutorial]$ locate libqt
    /usr/lib/qt-3.1/lib/libqt-mt.so.3.1.2
    /usr/lib/qt-3.1/lib/libqt-mt.so.3
    /usr/lib/qt-3.1/lib/libqt-mt.so.3.1
    /usr/lib/qt-3.1/lib/libqt.so.3.1
    /usr/lib/qt-3.1/lib/libqt.so.3
    /usr/lib/qt-3.1/lib/libqt.so.3.1.2
    /usr/lib/qt-3.1/lib/libqt-mt.so
    /usr/lib/qt-3.1/lib/libqt.so
    /usr/lib/libqthreads.so.12.3.0
    /usr/lib/libqthreads.so.12
    /usr/lib/libqtmcop.la
    /usr/lib/libqtmcop.so.1
    /usr/lib/libqtmcop.so.1.0.0
    /usr/lib/libqtmcop.so

    What we really want here is likely the libqt, so add the compile time
    library path via -L switches, and finally the short name (lib name - the
    'lib' prefix and the versioning) of the library we want to link against:

    [wegster@db KDETutorial]$ g++ main.cc -I /usr/lib/qt-3.1/include
    -L/usr/lib/qt-3.1/lib/ -lqt
    [wegster@db KDETutorial]$ ./a.out

    Works ;-)

    NOTE: This was done on a RHES system, because I've got the KDE
    development headers and libs installed. For FreeBSD, you'll need the qt
    sources or a KDE development package, although I'm not entirely sure
    which offhand...

    HTH,
    Scott

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