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  4. SIGSEGV (Segmentation fault) - Bad Pointer i guess
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SIGSEGV (Segmentation fault) - Bad Pointer i guess

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  • M Offline
    M Offline
    Matthacker
    wrote on last edited by
    #1

    Hi I have made a code for a system, an when I try to run it it crashes and comes with the code
    Signal name: SIGSEGV
    Signal meaning: Segmentation fault

    I think that it is because I am using a pointer incorrect, but cant figure out why it is wrong

    I have made a pointer in a class and want to use it in my mainwindow, and I have made a pointer in my mainwindow which i want to use in my class aswell. I know thats abit tricky.

    here is my code.
    @
    #ifndef SERIALSETUP_H
    #define SERIALSETUP_H
    #include <QMessageBox>
    #include <QDebug>
    #include <QSerialPort>

    #include "mainwindow.h"

    class SerialSetup
    {
    public:
    SerialSetup(MainWindow *myWindowPtr);
    void setupSerial();

    private:
    MainWindow *myWindowPtr_;
    QSerialPort *serialPtr_;
    };

    #endif // SERIALSETUP_H

    @

    @

    #include "serialsetup.h"

    SerialSetup::SerialSetup(MainWindow *myWindowPtr)
    {
    myWindowPtr_ = myWindowPtr;
    }

    void SerialSetup::setupSerial()
    {
    serialPtr_ = new QSerialPort(myWindowPtr_); // this is where it goes wrong!
    serialPtr_ ->setPortName("COM2");

    if(serialPtr_->open(QIODevice::ReadWrite))
    {
        qDebug("Serial Opened");
        QMessageBox::information(myWindowPtr_,myWindowPtr_->tr("Succesfull"),myWindowPtr_->tr("Succesfully connected to STK"));
        serialPtr_->setBaudRate(QSerialPort::Baud9600);
        serialPtr_->setDataBits(QSerialPort::Data8);
        serialPtr_->setParity(QSerialPort::NoParity);
        serialPtr_->setStopBits(QSerialPort::OneStop);
        serialPtr_->setFlowControl(QSerialPort::NoFlowControl);
        myWindowPtr_->connect(serialPtr_,SIGNAL(readyRead()),myWindowPtr_,SLOT(serialReceived()));
    }
    else
    {
        QMessageBox::warning(myWindowPtr_,myWindowPtr_->tr("Error"),myWindowPtr_->tr("Connection failed"));
        qDebug ("Serial NOT Opened");
        qDebug() << "error code = " << serialPtr_->error();
        qDebug() << "error string = " << serialPtr_->errorString();
    }
    

    }
    @

    and my mainwindow

    @
    #ifndef MAINWINDOW_H
    #define MAINWINDOW_H

    #include <QMainWindow>
    #include <QSerialPort>
    #include <QTimer>
    #include "modify_scenario.h"

    class SerialSetup;

    namespace Ui {
    class MainWindow;
    }

    class MainWindow : public QMainWindow
    {
    Q_OBJECT

    public:
    explicit MainWindow(QWidget *parent = 0, SerialSetup *setupPtr = 0 );

    ~MainWindow();
    

    private slots:
    void serialReceived();
    void on_Modify_button_clicked();
    void on_On_button_clicked();
    void on_Off_button_clicked();
    void on_Minus_button_clicked();
    void on_Plus_button_clicked();
    void on_Scenario1_button_clicked();
    void on_Scenario2_button_clicked();
    void on_Scenario3_button_clicked();
    void on_Load_button_clicked();
    void fcheckButton1();
    void fcheckButton2();
    void fcheckButton3();
    void fcheckLocked();
    //void serialSetup();
    void timeSetup();
    private:
    Ui::MainWindow *ui;
    Modify_Scenario *modify;
    SerialSetup *setupPtr_;
    QSerialPort *serial1Ptr_;
    QTime *time;
    bool Scenario1Chk, Scenario2Chk, Scenario3Chk, LockedChk,OpenChk;
    int counter;

    };

    #endif // MAINWINDOW_H

    @

    @
    #include "ui_mainwindow.h"
    #include "modify_scenario.h"
    #include "serialsetup.h"

    MainWindow::MainWindow(QWidget *parent, SerialSetup *setupPtr) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
    {

     ui->setupUi(this);
    
     setupPtr_ = setupPtr;
     setupPtr_ ->setupSerial();
    

    @

    can any of you figure out whats wrong ?

    Alex.

    1 Reply Last reply
    0
    • A Offline
      A Offline
      andreyc
      wrote on last edited by
      #2

      Where do you allocate SerialSetup?
      Is myWindowPtr_ a valid pointer at this line?
      @
      serialPtr_ = new QSerialPort(myWindowPtr_);
      @

      There is no any threads except main GUI thread in your app, right?

      1 Reply Last reply
      0
      • A Offline
        A Offline
        andreyc
        wrote on last edited by
        #3

        I think the fact that you are using myWindowPtr_ inside MainWindow constructor makes myWindowPtr_ invalid.

        1 Reply Last reply
        0
        • M Offline
          M Offline
          Matthacker
          wrote on last edited by
          #4

          Hi Andreyc

          thanks for your response.

          Have made the class SerialSetup to make the MainWindow cpp smaller.

          before I had
          @serialPtr_ = new QSerialPort(this); @

          inside MainWindow, and that worked. now instead of using this pointer I needed to have a pointer to the mainwindow and put it in there. but cant understand why that is wrong.

          dont think I am using the myWindowPtr_ inside MainWindow constructor, though I use it in SerialSetup constructor.

          Alex.

          1 Reply Last reply
          0
          • A Offline
            A Offline
            andreyc
            wrote on last edited by
            #5

            Could you show where do you create SerialSetup object?

            1 Reply Last reply
            0
            • M Offline
              M Offline
              Matthacker
              wrote on last edited by
              #6

              ahh I forgot to initialize the constructor, it never got in to it.!
              figured it out ;)

              thanks.!

              1 Reply Last reply
              0
              • A Offline
                A Offline
                andreyc
                wrote on last edited by
                #7

                Glad you solved it.
                Could you put [SOLVED] in the title of you message. Thanks.

                1 Reply Last reply
                0

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