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C++ - Can't access function in another class

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  • M mad-hatter

    Hello,

    I've got a problems accessing a function in another class.
    Help would be appriciated.

    Regards

    Compiler: GNU GCC 5.3.0
    Qt Version: 5.11.2
    System: Windows 10 (10.0)

    Header file for the class to access:-

    class QG_CommandEdit: public QLineEdit {
        Q_OBJECT
    
    public:
        QG_CommandEdit(QWidget* parent=0);
        virtual ~QG_CommandEdit()=default; //line 43 ****
    
        void readCommandFile(const QString& path);
        ... ...
    

    my.cpp file

    QString where = qApp->applicationDirPath().append("/").append(fileName); //this is valid
    
    QG_CommandEdit inst;
    inst.readCommandFile( where ); //line 222 ***
    
    errors:-
    error: undefined reference to `vtable for QG_CommandEdit'                  - qg_commandedit.h #43
    error: undefined reference to `QG_CommandEdit::QG_CommandEdit(QWidget*)'   - my.cpp #222
    
    K Offline
    K Offline
    koahnig
    wrote on last edited by
    #2

    @mad-hatter

    Is the associated source file included in the .pro file?

    Vote the answer(s) that helped you to solve your issue(s)

    1 Reply Last reply
    0
    • M Offline
      M Offline
      mad-hatter
      wrote on last edited by
      #3

      @koahnig

      Is the associated source file included in the .pro file?

      Yes.

      aha_1980A 1 Reply Last reply
      0
      • M mad-hatter

        @koahnig

        Is the associated source file included in the .pro file?

        Yes.

        aha_1980A Offline
        aha_1980A Offline
        aha_1980
        Lifetime Qt Champion
        wrote on last edited by
        #4

        @mad-hatter please clean your project (worst case: delete build directory), run qmake and build again.

        Qt has to stay free or it will die.

        1 Reply Last reply
        1
        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #5

          Hi,

          Usually, vtable related errors comes after you added or remove the Q_OBJECT macro. Either re-run qmake by hand or do as @aha_1980 suggested: nuke the build folder and re-build.

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          1 Reply Last reply
          2
          • M Offline
            M Offline
            mad-hatter
            wrote on last edited by
            #6

            Hello,

            Thanks for all your repies.

            Deleted build folder
            Deleted *.pro.usr
            Ran clean
            Ran Qmake
            Ran Rebuild

            Deleted build folder
            Deleted *.pro.usr
            Ran clean
            Ran Qmake
            Ran Build

            same errors,

            Is it something to do with virtual?
            virtual ~QG_CommandEdit()=default;

            Regards

            1 Reply Last reply
            0
            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #7

              Might be a silly question but did you implement your class constructor ?

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

              1 Reply Last reply
              2
              • M Offline
                M Offline
                mad-hatter
                wrote on last edited by
                #8

                @SGaist
                A silly answer, I don't know about class constructors in this context.

                jsulmJ 1 Reply Last reply
                0
                • M mad-hatter

                  @SGaist
                  A silly answer, I don't know about class constructors in this context.

                  jsulmJ Online
                  jsulmJ Online
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #9

                  @mad-hatter said in C++ - Can't access function in another class:

                  I don't know about class constructors in this context

                  Then you should learn.
                  Do you have this in your cpp file:

                  QG_CommandEdit::QG_CommandEdit(QWidget* parent=0)
                  {
                  }
                  

                  https://forum.qt.io/topic/113070/qt-code-of-conduct

                  1 Reply Last reply
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                  • M Offline
                    M Offline
                    mad-hatter
                    wrote on last edited by
                    #10

                    Hello,

                    Thanks for your response.
                    I can't change this file as its part of an open source project.

                    @jsulm
                    This is in the qg_commandedit.cpp file.

                    QG_CommandEdit::QG_CommandEdit(QWidget* parent)
                            : QLineEdit(parent)
                            , keycode_mode(false)
                            , relative_ray("none")
                            , calculator_mode(false)
                    
                    {
                        setStyleSheet("selection-color: white; selection-background-color: green;");
                        setFrame(false);
                        setFocusPolicy(Qt::StrongFocus);
                    }
                    

                    Regards

                    K 1 Reply Last reply
                    0
                    • M mad-hatter

                      Hello,

                      Thanks for your response.
                      I can't change this file as its part of an open source project.

                      @jsulm
                      This is in the qg_commandedit.cpp file.

                      QG_CommandEdit::QG_CommandEdit(QWidget* parent)
                              : QLineEdit(parent)
                              , keycode_mode(false)
                              , relative_ray("none")
                              , calculator_mode(false)
                      
                      {
                          setStyleSheet("selection-color: white; selection-background-color: green;");
                          setFrame(false);
                          setFocusPolicy(Qt::StrongFocus);
                      }
                      

                      Regards

                      K Offline
                      K Offline
                      koahnig
                      wrote on last edited by
                      #11

                      @mad-hatter

                      Show the .pro or .pri file where the source "qg_commandedit.cpp" is included.

                      Vote the answer(s) that helped you to solve your issue(s)

                      1 Reply Last reply
                      0
                      • M Offline
                        M Offline
                        mad-hatter
                        wrote on last edited by
                        #12

                        @koahnig

                        Pro file

                        TEMPLATE = app
                        
                        DISABLE_POSTSCRIPT = false
                        
                        #uncomment to enable a Debugging menu entry for basic unit testing
                        #DEFINES += LC_DEBUGGING
                        
                        DEFINES += DWGSUPPORT
                        DEFINES -= JWW_WRITE_SUPPORT
                        
                        LC_VERSION="2.2.0-alpha"
                        VERSION=$${LC_VERSION}
                        
                        # Store intermedia stuff somewhere else
                        GENERATED_DIR = ../../generated/librecad
                        # Use common project definitions.
                        include(../../common.pri)
                        include(./boost.pri)
                        include(./muparser.pri)
                        
                        CONFIG += qt \
                            warn_on \
                            link_prl \
                            verbose \
                            depend_includepath
                        
                        QT += widgets printsupport
                        CONFIG += c++11
                        *-g++ {
                            QMAKE_CXXFLAGS += -fext-numeric-literals
                        }
                        
                        GEN_LIB_DIR = ../../generated/lib
                        PRE_TARGETDEPS += $$GEN_LIB_DIR/libdxfrw.a \
                        		$$GEN_LIB_DIR/libjwwlib.a
                        
                        DESTDIR = $${INSTALLDIR}
                        
                        # Make translations at the end of the process
                        unix {
                            LC_VERSION=$$system([ "$(which git)x" != "x" -a -d ../../.git ] && echo "$(git describe --tags)" || echo "$${LC_VERSION}")
                        
                            macx {
                                TARGET = LibreCAD
                                VERSION=$$system(echo "$${LC_VERSION}" | sed -e 's/\-.*//g')
                                QMAKE_INFO_PLIST = Info.plist.app
                                DEFINES += QC_APPDIR="\"LibreCAD\""
                                ICON = ../res/main/librecad.icns
                                contains(DISABLE_POSTSCRIPT, false) {
                                    QMAKE_POST_LINK = /bin/sh $$_PRO_FILE_PWD_/../../scripts/postprocess-osx.sh $$OUT_PWD/$${DESTDIR}/$${TARGET}.app/ $$[QT_INSTALL_BINS];
                                    QMAKE_POST_LINK += /usr/libexec/PlistBuddy -c \"Set :CFBundleGetInfoString string $${TARGET} $${LC_VERSION}\" $$OUT_PWD/$${DESTDIR}/$${TARGET}.app/Contents/Info.plist;
                                }
                            }
                            else {
                                TARGET = librecad
                                DEFINES += QC_APPDIR="\"librecad\""
                                RC_FILE = ../res/main/librecad.icns
                                contains(DISABLE_POSTSCRIPT, false) {
                                    QMAKE_POST_LINK = cd $$_PRO_FILE_PWD_/../.. && scripts/postprocess-unix.sh
                                }
                            }
                        }
                        win32 {
                            TARGET = LibreCAD
                            DEFINES += QC_APPDIR="\"LibreCAD\""
                        
                            # add MSYSGIT_DIR = PathToGitBinFolder (without quotes) in custom.pro file, for commit hash in about dialog
                            !isEmpty( MSYSGIT_DIR ) {
                                LC_VERSION = $$system( \"$$MSYSGIT_DIR/git.exe\" describe --tags || echo "$${LC_VERSION}")
                            }
                        
                            RC_FILE = ../res/main/librecad.rc
                            contains(DISABLE_POSTSCRIPT, false) {
                                QMAKE_POST_LINK = "$$_PRO_FILE_PWD_/../../scripts/postprocess-win.bat" $$LC_VERSION
                            }
                        }
                        
                        DEFINES += LC_VERSION=\"$$LC_VERSION\"
                        
                        # Additional libraries to load
                        LIBS += -L../../generated/lib  \
                            -ldxfrw \
                            -ljwwlib
                        
                        INCLUDEPATH += \
                        HEADERS += ui/lc_actionfactory.h \
                            ....
                            ui/qg_commandedit.h \
                            ... 
                        SOURCES += ui/lc_actionfactory.cpp \
                            ...
                            ui/qg_commandedit.cpp \
                            ...
                        
                        1 Reply Last reply
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                        • sierdzioS Offline
                          sierdzioS Offline
                          sierdzio
                          Moderators
                          wrote on last edited by
                          #13

                          @mad-hatter said in C++ - Can't access function in another class:

                          INCLUDEPATH +=
                          HEADERS += ui/lc_actionfactory.h \

                          Add a newline between these lines! Or rather, remove the INCLUDEPATH entirely.

                          (Z(:^

                          1 Reply Last reply
                          1
                          • M Offline
                            M Offline
                            mad-hatter
                            wrote on last edited by
                            #14

                            @sierdzio

                            Thanks for your reply.
                            I don't want to alter the pro file as it belongs to an open source project that works as it is.

                            Regards

                            1 Reply Last reply
                            0
                            • sierdzioS Offline
                              sierdzioS Offline
                              sierdzio
                              Moderators
                              wrote on last edited by
                              #15

                              It is a bug, at least tell them to fix it if you don't want to do it yourself. If a project is open source, by the way, you do have all the rights to do that modification on your own.

                              (Z(:^

                              1 Reply Last reply
                              4
                              • M Offline
                                M Offline
                                mad-hatter
                                wrote on last edited by
                                #16

                                Hello,

                                @sierdzio

                                INCLUDEPATH +=
                                HEADERS += ui/lc_actionfactory.h \

                                I'm sorry, ' INCLUDEPATH += ' should not be there, its a copy and paste error on my part.

                                Regards

                                1 Reply Last reply
                                0
                                • M Offline
                                  M Offline
                                  mad-hatter
                                  wrote on last edited by
                                  #17

                                  Hello,

                                  I've changed the code and I am left with one error now.
                                  Is there something I should add in the header file?
                                  Help please!

                                  Regards

                                  QG_CommandEdit *inst = nullptr;
                                  inst->QG_CommandEdit::readCommandFile( where ); //line 248
                                  
                                  error: undefined reference to `QG_CommandEdit::readCommandFile(QString const&)' // line 248
                                  
                                  aha_1980A 1 Reply Last reply
                                  0
                                  • M mad-hatter

                                    Hello,

                                    I've changed the code and I am left with one error now.
                                    Is there something I should add in the header file?
                                    Help please!

                                    Regards

                                    QG_CommandEdit *inst = nullptr;
                                    inst->QG_CommandEdit::readCommandFile( where ); //line 248
                                    
                                    error: undefined reference to `QG_CommandEdit::readCommandFile(QString const&)' // line 248
                                    
                                    aha_1980A Offline
                                    aha_1980A Offline
                                    aha_1980
                                    Lifetime Qt Champion
                                    wrote on last edited by aha_1980
                                    #18

                                    Hi @mad-hatter

                                    Is there something I should add in the header file?

                                    That would help to resolve compile errors, when the compiler cannot find the definition of a function.

                                    Linker errors mean, the linker cannot find the implementation of the function.

                                    Usually this means either the implementation is missing in your source file or you have it in a source file that is not compiled/linked.

                                    Regards

                                    Qt has to stay free or it will die.

                                    1 Reply Last reply
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