QT crashed during running

Question

I'm trying to load some data from a file into a nested list. However, the application crashed during loading of the data. I found that the code crashed in appending data in my inner most list. Can someone please help me to understand what happened and how to fix it? Thanks.

header file(snp_plotter.h)

#ifndef SNP_PLOTTER_H
#define SNP_PLOTTER_H

#include <QMainWindow>

#include "QList"
#include <QtCharts/QChartGlobal>

QT_CHARTS_BEGIN_NAMESPACE
class QLineSeries;
class QChart;
QT_CHARTS_END_NAMESPACE
QT_CHARTS_USE_NAMESPACE

namespace Ui {
class SNP_Plotter;
}

class SNP_Plotter : public QMainWindow
{
    Q_OBJECT

public:
    explicit SNP_Plotter(QWidget *parent = 0);
    ~SNP_Plotter();

private slots:
    void on_openSnpFile_clicked();

private:
    Ui::SNP_Plotter *ui;
    QString nPorts;
    QString currentFile;
    QString snpData;
    QString snpHeader;
    QString domainType; //freq or time
    QString measureMethod; // s,y,abcd, etc
    QString measureType; // real+img, log+angl or linear+angl
    QString referenceImp; // system impd
    QList<QVector<double>*> listVector; //data list with [[][][]]
};

#endif // SNP_PLOTTER_H

code(main.cpp):

#include "snp_plotter.h"
#include "ui_snp_plotter.h"
#include "QFile"
#include "QFileDialog"
#include "QTextStream"
#include "QMessageBox"
#include "QDebug"
#include "QRegularExpression"
#include "QRegularExpressionMatch"
#include <QQueue>
#include <QList>
#include <QList>

SNP_Plotter::SNP_Plotter(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::SNP_Plotter)
{
    ui->setupUi(this);
    this->setCentralWidget(ui->verticalLayoutWidget);
}

SNP_Plotter::~SNP_Plotter()
{
    delete ui;
}

void SNP_Plotter::on_openSnpFile_clicked()
{
    // clean up the currntfile cache
    QString openFile = QFileDialog::getOpenFileName(this,
                                       tr("Open SNP file"),
                                       "/usr",
                                       "SNP(*.s*p)"
                                       );

    //extract number of ports
    QRegularExpression snpFormat(".s(\\d+)p");
    QRegularExpressionMatch match0 = snpFormat.match(openFile);
    nPorts = match0.captured(1);
    qint8 numberItems = 2*(nPorts.toInt()*nPorts.toInt())+1;
//    listVector = new QList<QList<double>*>(numberItems);

    for(auto i=0; i<numberItems; i++){
        QVector<double> *vector = new QVector<double>(1000);
        listVector.push_back(vector);
    }

    //open file
    QFile file(openFile);
    if (!file.open(QIODevice::ReadOnly | QFile::Text)) {
        QMessageBox::warning(this, "Warning", "Cannot open file: " + file.errorString());
        return;
    }


     QTextStream dataReading(&file);

     qint8 counter = 0;
     QRegularExpression headerFormat("#\\s+(\\w+)\\s+(\\w+)\\s+(\\w+)\\s+(\\w+)\\s+(\\w+)");
     QRegularExpression dataFormat("([^ ][-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?)");
     QString currentLine;
     while(!dataReading.atEnd()){
        //start a new line in the file
        currentLine = dataReading.readLine();

        //type of lines to skip
        if((currentLine[0]=="\x0")||(currentLine[0]=="!") ){continue;}

        //data extraction and insertion
        else if((currentLine[0]!="#")&&(currentLine[0]!="!")){
            QRegularExpressionMatchIterator dataList = dataFormat.globalMatch(currentLine);
            while(dataList.hasNext()){
                QRegularExpressionMatch matchedData = dataList.next();
                QString data = matchedData.captured(1);
                qInfo()<<data;
                listVector[counter%numberItems]->push_back(data.toDouble());  //crashed in this line 
                counter += 1;
            }
        }

        //header type extraction
        else if ((currentLine[0]=="#")) {
            QRegularExpressionMatch match2 = headerFormat.match(currentLine);
            domainType = match2.captured(1);
            measureType = match2.captured(2);
            measureMethod = match2.captured(3);
            referenceImp = match2.captured(5);
        }
     }
     qInfo()<<(listVector)[0]->size();
    // extraction completed, close file
     file.close();
}

the data that I'm trying to use

! S3P File: Measurements: Mag<S11> Ang<S11> Mag<S12> Ang<S12> Mag<S13> Ang<S13>! row 1 
!             Mag<S21> Ang<S21> Mag<S22> Ang<S22> Mag<S23> Ang<S23>! row 2 
!             Mag<S31> Ang<S31> Mag<S32> Ang<S32> Mag<S33> Ang<S33>! row 3 



# Hz S  dB   R 50
10000000 -52.282864 83.754532 -15.67896 -0.49186572 -1.5670134 -1.301762
-15.748223 -0.10280456 -50.764286 149.86646 -56.900387 -70.843872
-1.5776229 -1.2955924 -71.374367 -141.70441 -48.866203 65.932648
29987500 -60.731289 51.972256 -15.724875 -1.8122723 -1.5746148 -3.2653806
-15.716247 -1.8535374 -52.617325 178.46486 -62.476551 5.2978568
-1.5735339 -3.2886419 -65.686714 36.462376 -61.792774 9.9133005
49975000 -64.386765 2.9596229 -15.755823 -3.1201222 -1.5706615 -5.4831181
-15.738674 -3.0600834 -52.237274 169.75545 -58.964714 27.526367
-1.5741955 -5.4729681 -58.479481 47.793446 -56.108696 63.561378
69962500 -60.896507 -36.51757 -15.757278 -4.3601637 -1.577867 -7.6754441
-15.747104 -4.3896055 -50.548729 177.66254 -57.043007 9.1148758
-1.5749472 -7.6169047 -56.500164 6.8388286 -57.866039 -28.409134
89950000 -55.328976 -45.191593 -15.76739 -5.6117945 -1.5797645 -9.8418713
-15.749889 -5.5769963 -50.809414 173.62177 -57.651119 -0.7305429
-1.5803487 -9.7842817 -56.621773 5.4209571 -66.583694 23.118269
109937500 -60.013988 -42.251778 -15.770485 -6.7288284 -1.5785085 -12.021818
-15.764176 -6.7430348 -51.211327 170.20062 -56.137653 -1.5785257
-1.5805914 -11.985991 -55.860668 0.92532599 -58.335781 15.83968
129925000 -55.2337 -47.264515 -15.773083 -7.9232988 -1.5834771 -14.20496
-15.74941 -7.9423704 -52.448433 166.58505 -57.46785 -5.3259425
-1.5812542 -14.161623 -57.962692 0.68304181 -66.230148 -5.397459
149912500 -52.218529 -63.591721 -15.763268 -9.1296005 -1.5826913 -16.37332
-15.770909 -9.0827551 -51.982231 165.33054 -56.151371 -14.161432
-1.586452 -16.33128 -56.938805 -20.056446 -57.895336 -49.978813
169900000 -48.723946 -68.877541 -15.772202 -10.29782 -1.58857 -18.537006
-15.756567 -10.253307 -53.100327 166.75829 -57.286308 -21.661839
-1.5859301 -18.455862 -58.19286 -23.011927 -56.403473 -61.177219
189887500 -47.055653 -63.976929 -15.761551 -11.486256 -1.5892707 -20.66897
-15.756705 -11.417432 -52.570255 161.31961 -58.11451 -14.260036
-1.589681 -20.645853 -58.313042 -19.368044 -56.06601 -59.461319
209875000 -48.199955 -65.147034 -15.758836 -12.678895 -1.5931528 -22.858885
-15.750708 -12.633892 -54.576355 159.43607 -57.476353 -23.090178
-1.5905892 -22.808754 -57.229259 -22.673452 -53.756973 -77.388786
229862500 -47.620575 -65.079559 -15.761273 -13.856562 -1.5960027 -24.995838
-15.757499 -13.857363 -54.944546 168.24443 -57.51046 -25.383596
-1.5932056 -24.973335 -56.755974 -24.434172 -53.588017 -78.209816
249850000 -45.54829 -72.373695 -15.759305 -15.106434 -1.5959594 -27.192209
-15.754061 -15.04305 -56.757584 167.29137 -57.757648 -35.331924
-1.593374 -27.133352 -57.15892 -38.918037 -52.251003 -78.6092
269837500 -45.209282 -79.048836 -15.762296 -16.186449 -1.595193 -29.34836
-15.761364 -16.268795 -56.31012 155.37877 -58.96965 -36.80077
-1.6012613 -29.305353 -58.892376 -30.59782 -51.139919 -88.653198
289825000 -44.495762 -75.946327 -15.77701 -17.442837 -1.5954289 -31.487225
-15.759547 -17.546104 -57.791164 136.05252 -58.239506 -44.324471
-1.6040369 -31.49972 -58.461231 -38.748329 -50.686073 -102.10234
309812500 -43.302803 -82.000542 -15.766918 -18.634033 -1.5996813 -33.661705
-15.761863 -18.641865 -61.730743 144.8166 -60.559978 -37.826778
-1.6024027 -33.65374 -57.697384 -42.566422 -51.518753 -105.38393
329800000 -43.696449 -78.707024 -15.772308 -19.829834 -1.6114002 -35.827797
-15.758872 -19.892492 -61.704247 131.07913 -60.35778 -39.423588
-1.6023126 -35.767818 -59.314335 -32.67252 -52.212837 -96.09478
349787500 -41.770233 -79.74221 -15.764846 -21.037899 -1.6063002 -37.965122
-15.761175 -21.141983 -67.287781 106.3756 -59.302685 -45.419971
-1.6093071 -37.931061 -58.065773 -47.054985 -50.113159 -100.45293
369775000 -41.834766 -85.074005 -15.755595 -22.26008 -1.6062098 -40.106232
-15.755444 -22.253096 -67.486336 95.830017 -60.84161 -46.56329
-1.6086895 -40.089161 -59.786545 -45.948189 -49.895309 -123.41199
389762500 -40.628685 -85.450836 -15.762123 -23.489182 -1.6093255 -42.268429
-15.763054 -23.396936 -68.248146 81.470787 -60.379967 -55.129562
-1.608591 -42.201767 -61.377071 -50.809517 -50.866241 -127.41563
409750000 -40.523582 -86.431625 -15.7611 -24.674004 -1.6127316 -44.40868
-15.759981 -24.647635 -75.545479 166.72386 -58.76609 -50.209095
-1.6096529 -44.381767 -58.312939 -53.500042 -50.608158 -125.55299
429737500 -39.49865 -87.925888 -15.768126 -25.870119 -1.6137398 -46.560898
-15.756283 -25.906502 -74.112823 -93.561935 -59.226101 -58.54623
-1.6217877 -46.567924 -59.321663 -53.369888 -48.844105 -125.06399

the program will run and process the data until to the line of

129925000 -55.2337 -47.264515 -15.773083 -7.9232988 -1.5834771 -14.20496
-15.74941 -7.9423704 -52.448433 166.58505 -57.46785 -5.3259425
-1.5812542 -14.161623 -57.962692 0.68304181 -66.230148 -5.397459

Answer 1

You have too many double values to read all of them using qint8 type as counter. counter has type qint8, so you can hold signed integers in range [-128,127], when you assign value greater than 127 ( in your file there are more double values than 127) to your counter variable it is treated as negative number, and your app crash while calling index operator because counter%numberItems is negative value.

listVector[counter%numberItems]->push_back(data.toDouble()); // accessing list item with negative index

Change counter to wider integer type for example qint32 or reset counter value in somewhere in your code to avoid the overflow of int value.

Answer 2

So first off, you're allocating a whole lot of heap memory without ever clearing it afterwards. Each of those new statements without a corresponding delete will lead to a memory leak.

Also if the nPorts.toInt() conversion fails or parses incorrectly, you're going to get a numberItems equal to something odd. You then use that number to allocate listVector assuming it will have the size you expect. Then operate directly on it with subscript operators, without checking the actual size of the object or the number you used to allocate it.

Accessing a dynamically allocated object using subscript operators like that, without checking the actual size, could absolutely crash your program.

I believe your problem is with this line: (edit: didn't read the comment on this line initially, but glad you know that. this furthers my suspicions.)

listVector[counter%numberItems]->push_back(data.toDouble()); //crashed in this line

And it's because you're getting a segmentation fault from exceeding the bounds of your listVector object, which isn't the size you expect. I could be wrong, but there's at least some things to start investigating.