Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. creating cpp library using qt
Forum Updated to NodeBB v4.3 + New Features

creating cpp library using qt

Scheduled Pinned Locked Moved General and Desktop
23 Posts 3 Posters 7.5k Views 2 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • jsulmJ jsulm

    @amruz said in creating cpp library using qt:

    but when i tried to use the library in my application it is showing like qpushbutton cannot be found..qlabel not found..

    That indicates that you're forgot to link your app against needed Qt libraries. Or even header files cannot be found? Can you show your pro file? And the exact errors? Else we can just guess what is the problem

    A Offline
    A Offline
    amruz
    wrote on last edited by amruz
    #6

    @jsulm
    sharedlib.pro

    #-------------------------------------------------
    #
    # Project created by QtCreator 2017-07-27T15:45:22
    #
    #-------------------------------------------------
    
    QT       += widgets
    
    QT       -= core gui
    
    TARGET = worksharedlib
    TEMPLATE = lib
    
    DEFINES += WORKSHAREDLIB_LIBRARY
    
    SOURCES += worksharedlib.cpp
    
    HEADERS += worksharedlib.h\
            worksharedlib_global.h
    
    unix {
        target.path = /usr/lib
        INSTALLS += target
    }
    
    

    sharedlib.h

    #ifndef WORKSHAREDLIB_H
    #define WORKSHAREDLIB_H
    
    #include "worksharedlib_global.h"
    #include<qobject.h>
    #include<qwidget.h>
    #include <QPushButton>
    #include<QLineEdit>
    #include <QHBoxLayout>
    #include<qlabel.h>
    #include<QtGui>
    
    
    class WORKSHAREDLIBSHARED_EXPORT Worksharedlib:public QWidget
    {
    
       Q_OBJECT
    public:
        //Worksharedlib();
        Worksharedlib(QWidget *parent = 0);
        ~Worksharedlib() {}
    
    private slots:
    
       void handleButton();
    
       void m_buttonClicked();
    
    private:
    
       QPushButton *m_button;
    
       QLineEdit *m_textbox;
    
       QHBoxLayout *layout;
    
       QWidget *window;
    
       QLabel * label;
    
       QWidget *frame;
    
    };
    
    #endif // WORKSHAREDLIB_H
    
    

    sharedlib_global.h

    #ifndef WORKSHAREDLIB_GLOBAL_H
    #define WORKSHAREDLIB_GLOBAL_H
    
    #include <QtCore/qglobal.h>
    
    #if defined(WORKSHAREDLIB_LIBRARY)
    #  define WORKSHAREDLIBSHARED_EXPORT Q_DECL_EXPORT
    #else
    #  define WORKSHAREDLIBSHARED_EXPORT Q_DECL_IMPORT
    #endif
    
    #endif // WORKSHAREDLIB_GLOBAL_H
    
    

    sharedlib.cpp

    #include "worksharedlib.h"
    
    #include <QCoreApplication>
    #include <QMessageBox>
    #include <QDebug>
    using namespace std;
    
    Worksharedlib::Worksharedlib(QWidget *parent)
                                 : QWidget (parent)
    {
            layout = new QHBoxLayout( this );
            m_textbox = new QLineEdit ( this );
            // Create the button, make "this" the parent
            m_button = new QPushButton("My Button",this);
            // set size and location of the button
            m_button->setGeometry(QRect(QPoint(300, 200),
                                        QSize(200, 50)));
    
            //create the text box
            layout->addWidget(m_textbox);
            m_textbox->setGeometry(100,200,90,25);
    
    
            //try image
    
    
    
            //create a image viewer
            QString url = R"(/home/pi/krishna.jpg)";
            QPixmap img(url);
            QLabel *label = new QLabel(this);
            label->setGeometry(200,300,100,50);
            label->resize(this->width(),300);
            label->setPixmap(img);
            // Connect button signal to appropriate slot
            connect(m_button, SIGNAL (clicked()), this, SLOT (m_buttonClicked()));
    }
    
    void Worksharedlib::m_buttonClicked()
    {
        m_textbox = new QLineEdit;
        m_textbox->setPlaceholderText("Placeholder Text");
        m_textbox->setFocus();
        QMessageBox::information( this, "Information", "Just clicked Ui PushButton" );
    }
    
    
    

    in which all qt applications can i call this library.. what is the correct method to call this library in an application..

    jsulmJ 2 Replies Last reply
    0
    • A amruz

      @jsulm
      sharedlib.pro

      #-------------------------------------------------
      #
      # Project created by QtCreator 2017-07-27T15:45:22
      #
      #-------------------------------------------------
      
      QT       += widgets
      
      QT       -= core gui
      
      TARGET = worksharedlib
      TEMPLATE = lib
      
      DEFINES += WORKSHAREDLIB_LIBRARY
      
      SOURCES += worksharedlib.cpp
      
      HEADERS += worksharedlib.h\
              worksharedlib_global.h
      
      unix {
          target.path = /usr/lib
          INSTALLS += target
      }
      
      

      sharedlib.h

      #ifndef WORKSHAREDLIB_H
      #define WORKSHAREDLIB_H
      
      #include "worksharedlib_global.h"
      #include<qobject.h>
      #include<qwidget.h>
      #include <QPushButton>
      #include<QLineEdit>
      #include <QHBoxLayout>
      #include<qlabel.h>
      #include<QtGui>
      
      
      class WORKSHAREDLIBSHARED_EXPORT Worksharedlib:public QWidget
      {
      
         Q_OBJECT
      public:
          //Worksharedlib();
          Worksharedlib(QWidget *parent = 0);
          ~Worksharedlib() {}
      
      private slots:
      
         void handleButton();
      
         void m_buttonClicked();
      
      private:
      
         QPushButton *m_button;
      
         QLineEdit *m_textbox;
      
         QHBoxLayout *layout;
      
         QWidget *window;
      
         QLabel * label;
      
         QWidget *frame;
      
      };
      
      #endif // WORKSHAREDLIB_H
      
      

      sharedlib_global.h

      #ifndef WORKSHAREDLIB_GLOBAL_H
      #define WORKSHAREDLIB_GLOBAL_H
      
      #include <QtCore/qglobal.h>
      
      #if defined(WORKSHAREDLIB_LIBRARY)
      #  define WORKSHAREDLIBSHARED_EXPORT Q_DECL_EXPORT
      #else
      #  define WORKSHAREDLIBSHARED_EXPORT Q_DECL_IMPORT
      #endif
      
      #endif // WORKSHAREDLIB_GLOBAL_H
      
      

      sharedlib.cpp

      #include "worksharedlib.h"
      
      #include <QCoreApplication>
      #include <QMessageBox>
      #include <QDebug>
      using namespace std;
      
      Worksharedlib::Worksharedlib(QWidget *parent)
                                   : QWidget (parent)
      {
              layout = new QHBoxLayout( this );
              m_textbox = new QLineEdit ( this );
              // Create the button, make "this" the parent
              m_button = new QPushButton("My Button",this);
              // set size and location of the button
              m_button->setGeometry(QRect(QPoint(300, 200),
                                          QSize(200, 50)));
      
              //create the text box
              layout->addWidget(m_textbox);
              m_textbox->setGeometry(100,200,90,25);
      
      
              //try image
      
      
      
              //create a image viewer
              QString url = R"(/home/pi/krishna.jpg)";
              QPixmap img(url);
              QLabel *label = new QLabel(this);
              label->setGeometry(200,300,100,50);
              label->resize(this->width(),300);
              label->setPixmap(img);
              // Connect button signal to appropriate slot
              connect(m_button, SIGNAL (clicked()), this, SLOT (m_buttonClicked()));
      }
      
      void Worksharedlib::m_buttonClicked()
      {
          m_textbox = new QLineEdit;
          m_textbox->setPlaceholderText("Placeholder Text");
          m_textbox->setFocus();
          QMessageBox::information( this, "Information", "Just clicked Ui PushButton" );
      }
      
      
      

      in which all qt applications can i call this library.. what is the correct method to call this library in an application..

      jsulmJ Offline
      jsulmJ Offline
      jsulm
      Lifetime Qt Champion
      wrote on last edited by
      #7

      @amruz This is your shared lib, I'm talking about your app which uses the lib.

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

      A 1 Reply Last reply
      0
      • A amruz

        @jsulm
        sharedlib.pro

        #-------------------------------------------------
        #
        # Project created by QtCreator 2017-07-27T15:45:22
        #
        #-------------------------------------------------
        
        QT       += widgets
        
        QT       -= core gui
        
        TARGET = worksharedlib
        TEMPLATE = lib
        
        DEFINES += WORKSHAREDLIB_LIBRARY
        
        SOURCES += worksharedlib.cpp
        
        HEADERS += worksharedlib.h\
                worksharedlib_global.h
        
        unix {
            target.path = /usr/lib
            INSTALLS += target
        }
        
        

        sharedlib.h

        #ifndef WORKSHAREDLIB_H
        #define WORKSHAREDLIB_H
        
        #include "worksharedlib_global.h"
        #include<qobject.h>
        #include<qwidget.h>
        #include <QPushButton>
        #include<QLineEdit>
        #include <QHBoxLayout>
        #include<qlabel.h>
        #include<QtGui>
        
        
        class WORKSHAREDLIBSHARED_EXPORT Worksharedlib:public QWidget
        {
        
           Q_OBJECT
        public:
            //Worksharedlib();
            Worksharedlib(QWidget *parent = 0);
            ~Worksharedlib() {}
        
        private slots:
        
           void handleButton();
        
           void m_buttonClicked();
        
        private:
        
           QPushButton *m_button;
        
           QLineEdit *m_textbox;
        
           QHBoxLayout *layout;
        
           QWidget *window;
        
           QLabel * label;
        
           QWidget *frame;
        
        };
        
        #endif // WORKSHAREDLIB_H
        
        

        sharedlib_global.h

        #ifndef WORKSHAREDLIB_GLOBAL_H
        #define WORKSHAREDLIB_GLOBAL_H
        
        #include <QtCore/qglobal.h>
        
        #if defined(WORKSHAREDLIB_LIBRARY)
        #  define WORKSHAREDLIBSHARED_EXPORT Q_DECL_EXPORT
        #else
        #  define WORKSHAREDLIBSHARED_EXPORT Q_DECL_IMPORT
        #endif
        
        #endif // WORKSHAREDLIB_GLOBAL_H
        
        

        sharedlib.cpp

        #include "worksharedlib.h"
        
        #include <QCoreApplication>
        #include <QMessageBox>
        #include <QDebug>
        using namespace std;
        
        Worksharedlib::Worksharedlib(QWidget *parent)
                                     : QWidget (parent)
        {
                layout = new QHBoxLayout( this );
                m_textbox = new QLineEdit ( this );
                // Create the button, make "this" the parent
                m_button = new QPushButton("My Button",this);
                // set size and location of the button
                m_button->setGeometry(QRect(QPoint(300, 200),
                                            QSize(200, 50)));
        
                //create the text box
                layout->addWidget(m_textbox);
                m_textbox->setGeometry(100,200,90,25);
        
        
                //try image
        
        
        
                //create a image viewer
                QString url = R"(/home/pi/krishna.jpg)";
                QPixmap img(url);
                QLabel *label = new QLabel(this);
                label->setGeometry(200,300,100,50);
                label->resize(this->width(),300);
                label->setPixmap(img);
                // Connect button signal to appropriate slot
                connect(m_button, SIGNAL (clicked()), this, SLOT (m_buttonClicked()));
        }
        
        void Worksharedlib::m_buttonClicked()
        {
            m_textbox = new QLineEdit;
            m_textbox->setPlaceholderText("Placeholder Text");
            m_textbox->setFocus();
            QMessageBox::information( this, "Information", "Just clicked Ui PushButton" );
        }
        
        
        

        in which all qt applications can i call this library.. what is the correct method to call this library in an application..

        jsulmJ Offline
        jsulmJ Offline
        jsulm
        Lifetime Qt Champion
        wrote on last edited by
        #8

        @amruz said in creating cpp library using qt:

        in which all qt applications can i call this library.. what is the correct method to call this library in an application..

        You just link against your library and Qt in your app.
        See here http://doc.qt.io/qtcreator/creator-project-qmake-libraries.html

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

        1 Reply Last reply
        0
        • jsulmJ jsulm

          @amruz This is your shared lib, I'm talking about your app which uses the lib.

          A Offline
          A Offline
          amruz
          wrote on last edited by amruz
          #9

          @jsulm the pro file of my application which calls the library is

          QT += core
          QT -= gui
          
          CONFIG += c++11
          
          TARGET = testcretedlibrary
          CONFIG += console
          CONFIG -= app_bundle
          
          TEMPLATE = app
          
          SOURCES += main.cpp
          
          DEPENDPATH += /home/amruz/worksharedlib
          INCLUDEPATH += /home/amruz/worksharedlib
          LIBS += -L /home/amruz/build-worksharedlib-Desktop_Qt_5_7_0_GCC_64bit-Debug -lworksharedlib
          
          
          jsulmJ 1 Reply Last reply
          0
          • A amruz

            @jsulm the pro file of my application which calls the library is

            QT += core
            QT -= gui
            
            CONFIG += c++11
            
            TARGET = testcretedlibrary
            CONFIG += console
            CONFIG -= app_bundle
            
            TEMPLATE = app
            
            SOURCES += main.cpp
            
            DEPENDPATH += /home/amruz/worksharedlib
            INCLUDEPATH += /home/amruz/worksharedlib
            LIBS += -L /home/amruz/build-worksharedlib-Desktop_Qt_5_7_0_GCC_64bit-Debug -lworksharedlib
            
            
            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #10

            @amruz Add

            QT       += widgets
            
            

            Fix the LIBS line (no space between -L and the path):

            LIBS += -L/home/amruz/build-worksharedlib-Desktop_Qt_5_7_0_GCC_64bit-Debug -lworksharedlib
            

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

            A 1 Reply Last reply
            0
            • jsulmJ jsulm

              @amruz Add

              QT       += widgets
              
              

              Fix the LIBS line (no space between -L and the path):

              LIBS += -L/home/amruz/build-worksharedlib-Desktop_Qt_5_7_0_GCC_64bit-Debug -lworksharedlib
              
              A Offline
              A Offline
              amruz
              wrote on last edited by
              #11

              @jsulm said in creating cpp library using qt:

              QT += widgets

              can you also help me in writing the main.cpp file..
              how to actually call the mainwindow there with the library output in it

              jsulmJ 1 Reply Last reply
              0
              • A amruz

                @jsulm said in creating cpp library using qt:

                QT += widgets

                can you also help me in writing the main.cpp file..
                how to actually call the mainwindow there with the library output in it

                jsulmJ Offline
                jsulmJ Offline
                jsulm
                Lifetime Qt Champion
                wrote on last edited by
                #12

                @amruz You use it as any other library. You're already doing it with Qt.
                Just include the header file of your library and use it. For example create an instance of Worksharedlib.

                #include "sharedlib.h"
                
                int main()
                {
                    ...
                    Worksharedlib lib;
                    lib.show();
                    ...
                }

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

                A 1 Reply Last reply
                0
                • jsulmJ jsulm

                  @amruz You use it as any other library. You're already doing it with Qt.
                  Just include the header file of your library and use it. For example create an instance of Worksharedlib.

                  #include "sharedlib.h"
                  
                  int main()
                  {
                      ...
                      Worksharedlib lib;
                      lib.show();
                      ...
                  }
                  A Offline
                  A Offline
                  amruz
                  wrote on last edited by
                  #13

                  @jsulm said in creating cpp library using qt:

                  Worksharedlib lib;
                  lib.show();

                  i used the same way only.. but i am getting error as follows

                  /home/amruz/worksharedlib/worksharedlib.h:14: error: undefined reference to `vtable for Worksharedlib'

                  jsulmJ 1 Reply Last reply
                  0
                  • A amruz

                    @jsulm said in creating cpp library using qt:

                    Worksharedlib lib;
                    lib.show();

                    i used the same way only.. but i am getting error as follows

                    /home/amruz/worksharedlib/worksharedlib.h:14: error: undefined reference to `vtable for Worksharedlib'

                    jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on last edited by
                    #14

                    @amruz Will probably not solve that error, but this looks wrong as well:

                    QT -= gui
                    

                    Your app is going to show an UI, right? Then it is a gui app:

                    QT += core gui widgets
                    

                    Don't forget to rerun qmake after changing pro file and rebuild.

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

                    A 1 Reply Last reply
                    1
                    • jsulmJ jsulm

                      @amruz Will probably not solve that error, but this looks wrong as well:

                      QT -= gui
                      

                      Your app is going to show an UI, right? Then it is a gui app:

                      QT += core gui widgets
                      

                      Don't forget to rerun qmake after changing pro file and rebuild.

                      A Offline
                      A Offline
                      amruz
                      wrote on last edited by
                      #15

                      @jsulm said in creating cpp library using qt:

                      QT += core gui widgets

                      this is a console application actually..is that the problem?

                      jsulmJ 1 Reply Last reply
                      0
                      • A amruz

                        @jsulm said in creating cpp library using qt:

                        QT += core gui widgets

                        this is a console application actually..is that the problem?

                        jsulmJ Offline
                        jsulmJ Offline
                        jsulm
                        Lifetime Qt Champion
                        wrote on last edited by
                        #16

                        @amruz If it is a console application then why do you want to use a library which provides an UI class:

                        class WORKSHAREDLIBSHARED_EXPORT Worksharedlib:public QWidget
                        {
                        
                           Q_OBJECT
                        public:
                            //Worksharedlib();
                            Worksharedlib(QWidget *parent = 0);
                            ~Worksharedlib() {}
                        
                        private slots:
                           void handleButton();
                           void m_buttonClicked();
                        
                        private:
                           QPushButton *m_button;
                           QLineEdit *m_textbox;
                           QHBoxLayout *layout;
                           QWidget *window;
                           QLabel * label;
                           QWidget *frame;
                        };
                        

                        ?

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

                        A 1 Reply Last reply
                        0
                        • jsulmJ jsulm

                          @amruz If it is a console application then why do you want to use a library which provides an UI class:

                          class WORKSHAREDLIBSHARED_EXPORT Worksharedlib:public QWidget
                          {
                          
                             Q_OBJECT
                          public:
                              //Worksharedlib();
                              Worksharedlib(QWidget *parent = 0);
                              ~Worksharedlib() {}
                          
                          private slots:
                             void handleButton();
                             void m_buttonClicked();
                          
                          private:
                             QPushButton *m_button;
                             QLineEdit *m_textbox;
                             QHBoxLayout *layout;
                             QWidget *window;
                             QLabel * label;
                             QWidget *frame;
                          };
                          

                          ?

                          A Offline
                          A Offline
                          amruz
                          wrote on last edited by
                          #17

                          @jsulm which application should i use to test this library?

                          jsulmJ 1 Reply Last reply
                          0
                          • A amruz

                            @jsulm which application should i use to test this library?

                            jsulmJ Offline
                            jsulmJ Offline
                            jsulm
                            Lifetime Qt Champion
                            wrote on last edited by
                            #18

                            @amruz gui?

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

                            A 1 Reply Last reply
                            0
                            • jsulmJ jsulm

                              @amruz gui?

                              A Offline
                              A Offline
                              amruz
                              wrote on last edited by
                              #19

                              @jsulm do you mean qt widget application?

                              jsulmJ 1 Reply Last reply
                              0
                              • A amruz

                                @jsulm do you mean qt widget application?

                                jsulmJ Offline
                                jsulmJ Offline
                                jsulm
                                Lifetime Qt Champion
                                wrote on last edited by
                                #20

                                @amruz Yes. You're using widgets - so it must be a gui application with widgets, right?

                                QT += core gui widgets
                                

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

                                A 2 Replies Last reply
                                0
                                • jsulmJ jsulm

                                  @amruz Yes. You're using widgets - so it must be a gui application with widgets, right?

                                  QT += core gui widgets
                                  
                                  A Offline
                                  A Offline
                                  amruz
                                  wrote on last edited by
                                  #21

                                  @jsulm when i try to include this library in a widget application also i am getting the same error..

                                  this is the .pro file of my widgetapplication

                                  #-------------------------------------------------
                                  #
                                  # Project created by QtCreator 2017-07-27T17:19:21
                                  #
                                  #-------------------------------------------------
                                  
                                  QT       += core gui widgets
                                  
                                  greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
                                  
                                  TARGET = sharedlibtryinwidget
                                  TEMPLATE = app
                                  
                                  
                                  SOURCES += main.cpp\
                                          mainwindow.cpp
                                  
                                  HEADERS  += mainwindow.h
                                  
                                  DEPENDPATH += /home/amruz/worksharedlib
                                  INCLUDEPATH += /home/amruz/worksharedlib
                                  LIBS += -L/home/amruz/build-worksharedlib-Desktop_Qt_5_7_0_GCC_64bit-Debug -lworksharedlib
                                  
                                  
                                  
                                  A 1 Reply Last reply
                                  0
                                  • A amruz

                                    @jsulm when i try to include this library in a widget application also i am getting the same error..

                                    this is the .pro file of my widgetapplication

                                    #-------------------------------------------------
                                    #
                                    # Project created by QtCreator 2017-07-27T17:19:21
                                    #
                                    #-------------------------------------------------
                                    
                                    QT       += core gui widgets
                                    
                                    greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
                                    
                                    TARGET = sharedlibtryinwidget
                                    TEMPLATE = app
                                    
                                    
                                    SOURCES += main.cpp\
                                            mainwindow.cpp
                                    
                                    HEADERS  += mainwindow.h
                                    
                                    DEPENDPATH += /home/amruz/worksharedlib
                                    INCLUDEPATH += /home/amruz/worksharedlib
                                    LIBS += -L/home/amruz/build-worksharedlib-Desktop_Qt_5_7_0_GCC_64bit-Debug -lworksharedlib
                                    
                                    
                                    
                                    A Offline
                                    A Offline
                                    amruz
                                    wrote on last edited by
                                    #22

                                    @amruz i also found that when destructor is not included this type of error may occur..but when i added destructor also the same problem exists

                                    1 Reply Last reply
                                    0
                                    • jsulmJ jsulm

                                      @amruz Yes. You're using widgets - so it must be a gui application with widgets, right?

                                      QT += core gui widgets
                                      
                                      A Offline
                                      A Offline
                                      amruz
                                      wrote on last edited by amruz
                                      #23

                                      @jsulm it worked finally! thanks a lot for all the help

                                      the problem was qobject in the library , i removed it and it worked.

                                      1 Reply Last reply
                                      0

                                      • Login

                                      • Login or register to search.
                                      • First post
                                        Last post
                                      0
                                      • Categories
                                      • Recent
                                      • Tags
                                      • Popular
                                      • Users
                                      • Groups
                                      • Search
                                      • Get Qt Extensions
                                      • Unsolved