Qt 调试时输出语句

QString fileName = "D:/res/label14.txt";
QFile file(fileName);
if (!file.open(QIODevice::WriteOnly | QIODevice::Text))
{
QMessageBox::warning(NULL, "can not write", "can't write");
}
QTextStream in(&file);
for (int p = 0; p < Ef.rows; p++)
{
for (int q = 0; q < Ef.cols; q++)
{
in << Ef.at(p, q)<<" ";
}
in << "\n";
}
file.close();