Getting error when trying to access 2D QVector's elements.

[borasemiz]

Hello, I would like to create a matrix by using QVector. Could you tell me where I make mistake? Here is the code:

#include <QCoreApplication>
#include <QVector>
#include <QDebug>

int main(int argc, char* argv[]) {
    QCoreApplication a(argc, argv);
    QVector< QVector<double> > list(3);

    QVector<double> first(5, 1.0);
    QVector<double> second(5, 2.0);
    QVector<double> third(5, 3.0);

    list.append(first);
    list.append(second);
    list.append(third);

    qDebug() << list.at(0).at(0);

    return a.exec();
}

It is compiled successfully, but when I run it, it prompts a console output which says:

ASSERT failure in QVector<T>::at: "index out of range", file ../../Qt/5.4/gcc_64/include/QtCore/qvector.h, line 388

How can I solve this? If I use standard library vector class, would it solve?

[SGaist]

Hi,

You create list with three empty elements and then you append your three other vectors. So you have in fact list size that is 6 and the first three are empty hence the assert failure.

[borasemiz]

@SGaist Thank you :) This solved my problem.