data from serial port

[bhe]

hi all,

i'm newbie in qt, and i have to make a program in qt to read data from usb device, digital compass to be more precisely

and this is the part of my code

in .h file

private:
char buf[256];
QString line

private:
char buf[256];
QString line

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in .cpp

while(running) {
  res = read(fd, buf, 255);
  if(res > 1) {
    buf[res-1] = 0;
    line = buf;
    emit newData(line);
  }
}

while(running) {
  res = read(fd, buf, 255);
  if(res > 1) {
    buf[res-1] = 0;
    line = buf;
    emit newData(line);
  }
}

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but when i try to run it i got message : "The program has unexpectedly finished"
when i try to comment the "emit newData(line)" with "qDebug() << line;" it'll show the data that i want.
even when i try to use mid() function on line like this "line.mid(2,5)" it'll show the same message, but not with "line.length()"

my purpose it to emit the data, and parse in other class outside this file

anybody can help me please

thanks in advance

cheers,