File readline adds excess symbol

Question

I have a *.dat file with one string - localhost

a try to read this string and set host name

QFile file("file.dat");
if (file.open(QFile::ReadOnly)) {
    char buf[1024];
    qint64 lineLength = file.readLine(buf, sizeof(buf));
    QDebug() << buf;
    if (lineLength != -1) {
        db.setHostName(buf);
    }
}

I expected result of QDebug is: localhost, but I see a "localhost, with one quote. Also setHostName doesn't work because of the excess symbol - quote.

Why does the quote appear?