QByteArray Initialization

vivekyuvan

Hi Friends

I am facing an issue in QByteArray when QByteArray Initialization.

I can initialize a QByteArray like:

QByteArray m_data;
m_data[0] = 0x0c;
m_data[1] = 0x06;
m_data[2] = 0x04;
m_data[3] = 0x04;
m_data[4] = 0x02;
m_data[5] = 0x00;

But I would like something more compact, like:

QByteArray m_data{0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};

Unfortunately, this form isn't allowed:

error: could not convert '{12, 6, 4, 4, 2, 0}' from '<brace-enclosed initializer list>' to 'QByteArray'
QByteArray m_data{0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};

I want to pass m_data(array Data ) in emit signal. Any code example and snippet will be helpful.

Thanks In Advance

Best Regards
Vivek Yuvan

mostefa

HI @vivekyuvan

What if you initialize it like this:

QByteArray m_data("\x0c\x06\x04\x04\x02\x00",6);

?

vivekyuvan

HI @mostefa I got an an error like this below
error: could not convert '{12, 6, 4, 4, 2, 0}' from '<brace-enclosed initializer list>' to 'QByteArray'
QByteArray m_data{0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};

mostefa

@vivekyuvan said in QByteArray Initialization:

HI @mostefa I got an an error like this below
error: could not convert '{12, 6, 4, 4, 2, 0}' from '<brace-enclosed initializer list>' to 'QByteArray'
QByteArray m_data{0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};

Can you share the code of what you are doing exactly?

vivekyuvan

Hi @mostefa
Its a test code I want to initalize array in normal C Standard type

If I initialize qbyte array in Private Slot

Ex

QByteArray m_data={0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};

I got an error See the screen shot ![alt text]( image url)

mostefa

@vivekyuvan said in QByteArray Initialization:

Hi @mostefa
Its a test code I want to initalize array in normal C Standard type

If I initialize qbyte array in Private Slot

Ex
QByteArray m_data={0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};
I got an error See the screen shot ![alt text]( image url)

What if you change this line :

QByteArray m_data={0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};

To this following line :

QByteArray m_data = QByteArray("\x0c\x06\x04\x04\x02\x00",6);

QByteArray Constructor

vivekyuvan

Hi@mostefa

QByteArray m_data = QByteArray("\x0c\x06\x04\x04\x02\x00",6);

The Error message gone and I got the output thanks. But I want to send the array to emit signal? is that possible ? I am newbie to QT soft/Development guide me to resolve this problem

mostefa

@vivekyuvan said in QByteArray Initialization:

Hi@mostefa The Error message gone and I got the output thanks. But I want to send the array to emit signal? is that possible ? I am newbie to QT soft/Development guide me to resolve this problem

You can actually send array in signal,

let's say you have the following signal :

void sendByteArray(QByteArray);// on your .h file

inside your testArrayInitialization you can do something like this :

QByteArray m_data = QByteArray("\x0c\x06\x04\x04\x02\x00",6);
emit sendByteArray(m_data);

If this is not what you want , can you explain what you want to do?

vivekyuvan

@mostefa thanks The problem is solved

mostefa

You are welcome =) , you can change the state of your post to solved

titan83

What about:

QByteArray text = QByteArray::fromHex("517420697320677265617421");

jsulm

@titan83 This is just a string containing ASCII characters.
It should be like @mostefa shown:

QByteArray m_data = QByteArray("\x0c\x06\x04\x04\x02\x00",6);

joaopagotto

Hi friend, use this:

#include <QCoreApplication>

int main(int argc, char *argv[])
{
   QCoreApplication a(argc, argv);

   QByteArray data;

   data.append((char)0x0c);
   data.append((char)0x06);
   data.append((char)0x04);
   data.append((char)0x04);
   data.append((char)0x02);
   data.append((char)0x00);
   data.append((char)0xFF);

   printf("%d\n", data.size());
   printf("%s\n", data.toHex().toStdString().c_str());

   return a.exec();   
}

jsulm

@joaopagotto This is actually the same he already did. He asked for something like this or similar:

QByteArray m_data{0x0c, 0x06, 0x04, 0x04, 0x02, 0x00};

Also there is no need to use printf in C++. Instead of

printf("%d\n", data.size());

you can just write

qDebug() << data.size();

or C++ without Qt

std::cout << data.size();

vivekyuvan

This post is deleted!

aha_1980

@jsulm said in QByteArray Initialization:

@titan83 This is just a string containing ASCII characters.

Of course @titan83 has a point here. His string is made of ASCII characters, but he uses QByteArray::fromHex(). This may not be the fastest operation, but allows to read the data from UI or an ASCII file, for example.

delverdl

You can basically use a C++11 initializer list the following way (I've added a char higher than 0x7f and initializtion by variables):

char        v1 = 0x06, v2 = 0x04;
QByteArray  ba(std::begin<char>({0x0c, v1, v2, v2, 0x02, 0x00, '\xf3'}), 7);