QT——QString转QByteArray16进制并自动补0

void MainWindow :: String2Hex ( QString str , QByteArray & senddata )

{

    int hexdata,lowhexdata;

        int hexdatalen = 0;

        int len = str.length();

        senddata.resize(len/2);

        char lstr,hstr;

        for(int i=0; i<len; )

        {

            //char lstr,

            hstr=str[i].toLatin1();

            if(hstr == ' ')

            {

                i++;

                continue;

            }

            i++;

            if(i >= len)

                break;

            lstr = str[i].toLatin1();

            hexdata = ConvertHexChar(hstr);

            lowhexdata = ConvertHexChar(lstr);

            if((hexdata == 16) || (lowhexdata == 16))

                break;

            else

                hexdata = hexdata*16+lowhexdata;

            i++;

            senddata[hexdatalen] = (char)hexdata;

            hexdatalen++;

        }

        senddata.resize(hexdatalen);

}
char MainWindow::ConvertHexChar(char ch)

{

    if((ch >= '0') && (ch <= '9'))

            return ch-0x30;

        else if((ch >= 'A') && (ch <= 'F'))

            return ch-'A'+10;

        else if((ch >= 'a') && (ch <= 'f'))

            return ch-'a'+10;

        else return (-1);

}

int main()
{

QString dbm ;
QByteArray db_m;
char db_buff[10]={0};

dbm = ui -> lineEdit_dB -> text ();
unsigned int db = dbm . toInt ();
sprintf ( db_buff , "%x" , db );
if ( strlen ( db_buff )% 2 )

    {

          qDebug("奇数");

          for(i=0;i<strlen(db_buff)+1;i++)

          {

              db_buff[strlen(db_buff)-i+1] = db_buff[strlen(db_buff)-i];

          }

         db_buff[0]='0';

         dbm=QString::fromLocal8Bit(db_buff,strlen(db_buff));

         qDebug("db_buffm%s",db_buff);

         memset(db_buff,0,strlen(db_buff));

    }

    else

    {

       dbm=QString::fromLocal8Bit(db_buff,strlen(db_buff));

    }

    String2Hex(dbm,db_m);
    serial->write(db_m);

}