I need to convert a QTextStream to a QByteArray, and then back again. I found an example of QTextStream -> QByteArray by constructing a QTextStream(QBytearray) and then any text < < to the stream ends up in the bytearray.
But how about the other way? Probably a one liner but I can figure it out. Can someone post and explain?
Check it out if your text stream works via file (maybe via socket):
QFile file(fileName);
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return;
QTextStream in(&file);
QString text;
text = in.readAll();
file.close();
text.QString::toUtf8(); //convert your data to byte array
To get your data back use: QString::fromUtf8(const QByteArray &str)
Related
I have a QByteArray i create manually:
QByteArray hexArray(QByteArray::fromHex("495676"));
If this was encoded ASCII it would be "IVv".
If I want to get a single byte of data from that array.
I can do that like this:
qDebug() << messageToBeSent_raw[0];
However, that outputs I, which is correct but I would like to get 49. What I'm looking for is an equivalent of the QByteArray::toHex() just for a single byte. Is there a way to do it?
You can use QString::number.
qDebug() << QString::number(hexArray[0], 16);
How can I read only first word in every line in a text file while using QFile in Qt?
Thanks.
use
QFile ifile("in.txt");
QString text = txStream.readLine();
QStringList splitline = text.split(" ");
QFile ofile("out.txt");
ofile.open(QIODevice::WriteOnly | QIODevice::Text);
QTextStream out(&ofile);
// join QStringList by "\n" to write each single word in an own line
out << splitline.join("\n");
ofile.close();
I am new to Qt and need to prepare a project to send hex commands from rs232.
QString line contains 64bit binary data which i have to convert into hexadecimal and send it through rs232 .
QString a=ui->comboBox->currentText();
QString s1;
s1="./calc "+a;
QProcess p1;
p1.start(s1);
p1.waitForFinished(-1);
QString line ;
//read
QFile file("TeleOutput.txt");
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return;
QTextStream in (&file);
line = in.readAll();
ui->plainTextEdit->setPlainText(line);
So, how to convert 64 bit binary data in QString line to hexadecimal value and transfer it through rs232?
First of all - you should really use QtSerialPort
Second of all - QString is a class, which works with actual string. QByteArray works with raw data. When you write QString line = in.readAll(); it implicitly calls QString(const QByteArray &ba), which uses QString::fromAscii.
Last of all, if you want to process 64bit integers, you should do something like this:
quint64 d;
QDataStream stream(&file);
while (!stream.atEnd())
{
stream >> d;
process(d);
}
Update
Quote:
My problem is that in plainTextEdit
"1111110101000101010101010101010101010101010101010101010......." 64
bit data is populated , i need to convert this data into hex and send it through rs232
Solution:
QString binData = plainTextEdit.toPlainText();
QByteArray result;
while (binData.size() >= 64)
{
quint64 d;
QString dataPiece = binData.left(64);
binData.remove(0, 64);
d = dataPiece.toULongLong(0, 2);
result += QByteArray::number(d);
}
_com->write(result);
_com->flush();
Where _com is a pointer to QtSerialPort, with all parameters set and opened without errors.
Will this work?
QString bozo;
QFile filevar("sometextfile.txt");
QTextStream in(&filevar);
while(!in.atEnd()) {
QString line = in.readLine();
bozo = bozo + line;
}
filevar.close();
Will bozo be the entirety of sometextfile.txt?
Why even read line by line? You could optimize it a little more and reduce unnecessary re-allocations of the string as you add lines to it:
QFile file(fileName);
if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) return;
QTextStream in(&file);
QString text;
text = in.readAll();
file.close();
As ddriver mentions, you should first open the file using file.open(…); Other than that, yes bozo will contain the entirety of the file using the code you have.
One thing to note in ddriver's code is that text.reserve(file.size()); is unnecessary because on the following line:
text = in.readAll();
This will replace text with a new string so the call to text.reserve(file.size()); would have just done unused work.
i need add on firt position of qbytearray a quint16 and after read it: How can i to do it?
I have try this:
quint16 pos = 0;
QFile file(m_pathFile);
if (file.open(QFile::ReadOnly))
{
qDebug() << "el fichero existe";
m_udpSocket->bind(m_port);
QByteArray datagram;
while (!file.atEnd())
{
datagram.begin();
datagram.append(pos++);
datagram = file.read(m_blockSize);
qDebug() << "Sec" << datagram.at(0);
}
}
Thanks you very much
I got add with:
datagram.begin();
datagram.setNum(pos, 10);
datagram.append(file.read(m_blockSize));
but i don't know as read it
Thanks
Ok, first of all, that datagram.begin() is useless since it returns an iterator that you don't assign at all. If you want to insert a number in the first position of a QByteArray you can do something like:
datagram.insert(0, QString::number(pos++));
To read it, the simplest way is to use a QTextStream like this:
QTextStream str(datagram);
quint16 num;
str >> num;
Also, take a look at the docs before posting, because the Qt ones are really simple and helpful if you know how to search (and it's not that difficult, trust me).