QFileDialog::getSaveFileName Cancel Button

[penny]

I'm using QFileDialog::getSaveFileName to save a file.

QString saveFileName = QFileDialog::getSaveFileName(this,"Save As","./untitled.dat",tr("files(*.dat )"));
saveFile(saveFileName);
QMessageBox::StandardButton reply;
reply = QMessageBox::information(this, tr(" "), "File Saved");

QString saveFileName = QFileDialog::getSaveFileName(this,"Save As","./untitled.dat",tr("files(*.dat )"));
saveFile(saveFileName);
QMessageBox::StandardButton reply;
reply = QMessageBox::information(this, tr(" "), "File Saved");

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I cannot understand how to recognize whether Save has been pressed or Cancel button. Currently my application saves the file even if i press cancel.