Append/Prepend QString to QByteArray

[ermustaqbal]

Hi,

I have a question about QByteArray.

assume that i have a source like this


QByteArray ba;

QString inName = QFileDialog::getOpenFileName(this, "Load a file");
QFile *fileIn = new QFile(inName);
fileIn->open(QIODevice::ReadOnly);


ba = fileIn->readAll();


"ba" is a QByteArray, i want to append QString after ba. How can i do that? because when i use QByteArray::append() i can't see anything change, and after i try to write ba as a file again, it is still the same like before.

Thanks in advanced,


ps: my file is binary(video) file

[mcosta]

can you post your code???

[ermustaqbal]

can you post your code???



QByteArray ba;

QString inName = QFileDialog::getOpenFileName(this, "Load a file");
QFile *fileIn = new QFile(inName);
fileIn->open(QIODevice::ReadOnly);


ba = fileIn->readAll();
qDebug() << ba;
qDebug() << ba.length();
fileIn->close();

QByteArray acba = ba;
QString key = "thisisakey";
acba = acba.append(key);
qDebug() << acba; //i hope here will go "thisisakey" appended

QString outName = QFileDialog::getSaveFileName(this, "Save a file");
QFile *fileOut = new QFile(outName);
fileOut->open(QIODevice::WriteOnly);

fileOut->write(acba); // i will fail save the same file as before because i have append it with key,
// but the result it is success, and it means there is no change.
fileOut->flush();
fileOut->close();

[wysota]

What does acba.size() return after line 15 compared to its result before this line?

[ermustaqbal]

What does acba.size() return after line 15 compared to its result before this line?

wysota after i print it out i have something like this :

before append: 26246026
after append: 26246036

it means the key succesfully appended?

Added after 54 minutes:

Hohoho got it, thanks wysota you make me think about size ... thanks a lot ...

[mcosta]

size increeased of 10 (size of "thisisakey");

This code works for me.


QByteArray ba ("1234567890");
qDebug () << ba;

ba = ba.append(QString("Hello World"));
qDebug () << ba;


If your file is a binary one, writing on console is wrong because at the first 0x00 byte the output will be truncated.