When Qt5 combobox added item, it was added twice in the list. Does anyone know why?

when Qt5 combobox adds item, the list appears to be added twice 

void MainWindow::initSerialPort()
{
  foreach(const QSerialPortInfo &info, QSerialPortInfo::availablePorts())
  {
    qDebug()<<"Name"<<info.portName();
    qDebug()<<"Description"<<info.description();
    qDebug()<<"Manufacture"<<info.manufacturer();

    QSerialPort port;
    port.setPort(info);
    if(port.open(QIODevice::ReadWrite))
    {
        ui->cmbComName->addItem(info.portName());
        port.close();
    }

    QStringList baudRateList;
    baudRateList <<"4800"<<"9600"<<"19200"<<"57600"<<"115200";
    ui->cmdBaudRate->addItems(baudRateList);
    ui->cmdBaudRate->setCurrentIndex(1);

  }
}

Qt5
Apr.12,2022

Why does the UI control call addItem

foreach

Previous: Golang one goroutine write, one read, will it also produce static?

Next: How to traverse QCheckBox in QGridLayout in qt5

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b39ec2-2c1cb.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b39ec2-2c1cb.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?