QTableWidget and the setHorizontalHeaderItem/setVerticalHeaderItem functions

[Lykurg]

And dimension points to the same value as rows and columns in SquareMatrix...

I thought so because of the name. But you never know here... So only thing I can guess of (without proving it) is, that you cant reuse one item for vertical and horizontal header. So try:

matrixTable->setHorizontalHeaderItem(row, new QTableWidgetItem(names.at(row)));
matrixTable->setVerticalHeaderItem(row, new QTableWidgetItem(names.at(row)));

matrixTable->setHorizontalHeaderItem(row, new QTableWidgetItem(names.at(row)));
matrixTable->setVerticalHeaderItem(row, new QTableWidgetItem(names.at(row)));

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If that is also not helping, debug and backtrace to see where it exactly crashes.