how to read coordinates points from text file

[rafik]

Hello,

i want to read points coordinats from a text file, how can i do that please?

2.0000000e+000 8.1000000e+001
3.0000000e+000 6.9000000e+001
6.0000000e+000 1.5500000e+002
1.2000000e+001 1.2400000e+002
1.2000000e+001 2.2800000e+002
2.4000000e+001 1.9200000e+002
2.4000000e+001 2.1600000e+002
2.8000000e+001 2.3700000e+002

there are spaces between the X and Y coordinates
help me please and thank you.

[anda_skoa]

QFile, QTextStream::readLine(), QString::split().

Cheers,
_

[rafik]

Thank you for your reply, but i tried this and i have a runTime error

#include <QApplication>
#include <QtWidgets>
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QWidget f;
 
    QFile monFichier("C:/Users/amine/Downloads/dcis/dcis1.txt");
 
        double x = 0.0;
        double y = 0.0;
 
        QTextStream ts(&monFichier);
        QString line;
            line = ts.readLine();
            QStringList s = line.split(" ",QString::SkipEmptyParts);
            x = s.at(0).toDouble();
            y = s.at(1).toDouble();
 
         QLCDNumber *lcd1 = new QLCDNumber(&f);
         lcd1->setSegmentStyle(QLCDNumber::Flat);
         lcd1->move(100, 100);
         QLCDNumber *lcd2 = new QLCDNumber(&f);
          lcd2->setSegmentStyle(QLCDNumber::Flat);
          lcd2->move(170, 100);
 
          lcd1->display(x);
          lcd2->display(y);
          f.show();
 
 
    return app.exec();
 
}

#include <QApplication>
#include <QtWidgets>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QWidget f;

    QFile monFichier("C:/Users/amine/Downloads/dcis/dcis1.txt");

        double x = 0.0;
        double y = 0.0;

        QTextStream ts(&monFichier);
        QString line;
            line = ts.readLine();
            QStringList s = line.split(" ",QString::SkipEmptyParts);
            x = s.at(0).toDouble();
            y = s.at(1).toDouble();

         QLCDNumber *lcd1 = new QLCDNumber(&f);
         lcd1->setSegmentStyle(QLCDNumber::Flat);
         lcd1->move(100, 100);
         QLCDNumber *lcd2 = new QLCDNumber(&f);
          lcd2->setSegmentStyle(QLCDNumber::Flat);
          lcd2->move(170, 100);

          lcd1->display(x);
          lcd2->display(y);
          f.show();


    return app.exec();

}

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---

Added after 10 minutes:

there are some spaces in the begining and between the coordinates

[Lesiok]

Read about QString::trimmed() - manual is the best friend the programmer.

[yeye_olive]

If I remember correctly, QTextStream's extraction operator (>>) interprets whitespace as a separator between values. Perhaps all you have to do is:

double x, y;
ts >> x >> y;

double x, y;
ts >> x >> y;

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[rafik]

thank you all for your replies , yeye_olive your instruction give the result, thank you

---

Added after 31 minutes:

i have another problem, i don't want to read the last line in the text file, because if i do a loop and read the coordinates the program display x as 0.0 and y as 0.0
so my question is : to stop reading coordinates when it reaches the line before the last line if it is possible.
How can i do that please.

#include <QApplication>
#include <QtWidgets>
 
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QWidget f;
 
    QFile monFichier("C:/Users/amine/Downloads/dcis/dcis1.txt");
    monFichier.open(QIODevice::ReadOnly);
 
        double x = 0.0;
        double y = 0.0;
 
        QTextStream ts(&monFichier);
        while(!ts.atEnd())
        {
            ts >> x >> y;
        }
 
         QLCDNumber *lcd1 = new QLCDNumber(&f);
         lcd1->setSegmentStyle(QLCDNumber::Flat);
         lcd1->move(100, 100);
         QLCDNumber *lcd2 = new QLCDNumber(&f);
          lcd2->setSegmentStyle(QLCDNumber::Flat);
          lcd2->move(170, 100);
 
          lcd1->display(x);
          lcd2->display(y);
          f.show();
 
    return app.exec();
 
}

#include <QApplication>
#include <QtWidgets>


int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QWidget f;

    QFile monFichier("C:/Users/amine/Downloads/dcis/dcis1.txt");
    monFichier.open(QIODevice::ReadOnly);

        double x = 0.0;
        double y = 0.0;

        QTextStream ts(&monFichier);
        while(!ts.atEnd())
        {
            ts >> x >> y;
        }

         QLCDNumber *lcd1 = new QLCDNumber(&f);
         lcd1->setSegmentStyle(QLCDNumber::Flat);
         lcd1->move(100, 100);
         QLCDNumber *lcd2 = new QLCDNumber(&f);
          lcd2->setSegmentStyle(QLCDNumber::Flat);
          lcd2->move(170, 100);

          lcd1->display(x);
          lcd2->display(y);
          f.show();

    return app.exec();

}

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[Lesiok]

Read data with first method (readLine()) and test whether the length is greater then 0.