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SIGSEGV (Segmentation fault) - Bad Pointer i guess

  • 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
    SerialSetup(MainWindow *myWindowPtr);
    void setupSerial();

    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");

        qDebug("Serial Opened");
        QMessageBox::information(myWindowPtr_,myWindowPtr_->tr("Succesfull"),myWindowPtr_->tr("Succesfully connected to STK"));
        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

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


    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();
    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) :
    ui(new Ui::MainWindow)

     setupPtr_ = setupPtr;
     setupPtr_ ->setupSerial();


    can any of you figure out whats wrong ?


  • 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?

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

  • 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.


  • Could you show where do you create SerialSetup object?

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


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

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