OS: Ubuntu 18.02
GCC version 7.4.0
QMake Version 3.1
Qt Version 5.9.5
QWT Version 6.1.4

Hello Everyone!

I created a qwtplot array, and set a point on origin.

When I delete the qwtplot array before close qt windows, the Qt program is crashed.

The Code is show in the following

mainwindows.h
Qt Code: 
  1. #include <QMainWindow>
  2. #include <qwt_plot.h>
  3. #include <qwt_plot_curve.h>
  4. #include <qwt_plot_grid.h>
  5. #include <qwt_plot_canvas.h>
  6. #include <qwt_plot_curve.h>
  7. #include <qwt_plot_grid.h>
  8. #include <qwt_symbol.h>
  9. #include <QPolygonF>
  10. namespace Ui {
  11. class MainWindow;
  12. }
  13. class MainWindow : public QMainWindow
  14. {
  15.     Q_OBJECT
  16. public:
  17.     explicit MainWindow(QWidget *parent = 0);
  18.     ~MainWindow();
  19. private:
  20.     Ui::MainWindow *ui;
  21.     QwtPlot *qwtpt;
  22.     QPolygonF *polygon;
  23.     QwtPlotCurve *curve;
  24.     QwtPlotGrid *grid;
  25.     QwtSymbol *symbol;
  26. };
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mainwindow.cpp
Qt Code: 
  1. MainWindow::MainWindow(QWidget *parent) :
  2.     QMainWindow(parent),
  3.     ui(new Ui::MainWindow)
  4. {
  5.     ui->setupUi(this);
  6.     int numpoints = 10;
  7.     qwtpt = new QwtPlot[numpoints];
  8.     polygon = new QPolygonF[numpoints];
  9.     curve = new QwtPlotCurve[numpoints];
  10.     grid = new QwtPlotGrid[numpoints];
  11.     symbol = new QwtSymbol[numpoints];
  12.     QString style = "color: white; ";
  13.     QPolygonF initialpoint;
  14.     initialpoint << QPointF(0.0f, 0.0f);
  15.     int k;
  16.     for(k = 0; k < numpoints; ++k){
  17.         //plot
  18.         qwtpt[k].setParent(ui->scrollArea);
  19.         qwtpt[k].setGeometry(10, 20 + 181 * k, 760, 161);
  20.         qwtpt[k].setAxisTitle(QwtPlot::xBottom, "points");
  21.         qwtpt[k].setAxisTitle(QwtPlot::yLeft, "efficience %");
  22.         qwtpt[k].setAxisScale(QwtPlot::xBottom, 0.0, 132);
  23.         qwtpt[k].setAxisScale(QwtPlot::yLeft, 0.0, 100);
  24.         qwtpt[k].setStyleSheet(style);
  25.         //symbol
  26.         symbol[k].setPen(QPen(Qt::red, 2));
  27.         symbol[k].setStyle(QwtSymbol::Ellipse);
  28.         symbol[k].setBrush(QBrush(Qt::yellow));
  29.         symbol[k].setSize(QSize(8,8));
  30.         //curve
  31.         curve[k].setPen(Qt::blue, 4);
  32.         curve[k].setRenderHint(QwtPlotItem::RenderAntialiased, true);
  33.         curve[k].setSymbol(&symbol[k]);
  34.         curve[k].attach(&qwtpt[k]);
  35.         curve[k].setSamples(initialpoint);
  36.         //grid
  37.         grid[k].attach(&qwtpt[k]);
  38.     }
  39. }
  40. MainWindow::~MainWindow()
  41. {
  42.     delete [] qwtpt;	//  crash on this line
  43.     delete [] polygon;
  44.     delete [] curve;
  45.     delete [] grid;
  46.     delete [] symbol;
  47.     delete ui;
  48. }
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if I do not to delete the qwtpt array, the Qt debug show the crash on function ~MainWindow()

if I exchange position between qwtpt and curve, the crash is happened on “delete [] curve”
Qt Code: 
  1. delete [] curve;	//  crash on this line
  2.      delete [] polygon;
  3.      delete [] qwtpt;
  4.      delete [] grid;
  5.      delete [] symbol;
  6.      delete ui;
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Maybe I must to do something before delete the qwtplot array.

Is anyone have idea, or some suggestion for this issues?

Thanks in advance.