Get hex from Qlineedit and send to serial port

[hovuquocan1997]

Thank you for the reply, here is what I have so far and it's still not working,

void MainWindow::on_pushButton_3_clicked() //testing button
{
    ui->lineEdit_2->setInputMask("hhhhhhhhhhhhhh");
    QString input = ui->lineEdit_2->text();
    bool ok;
    char command=input.toInt(&ok,16);
    serial->write(command,sizeof(command));
}

void MainWindow::on_pushButton_3_clicked() //testing button
{
    ui->lineEdit_2->setInputMask("hhhhhhhhhhhhhh");
    QString input = ui->lineEdit_2->text();
    bool ok;
    char command=input.toInt(&ok,16);
    serial->write(command,sizeof(command));
}

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and also is there a method to input as many as hex pairs as I want? Since setinputmask restricts my input to only that many that I set. Thank you.