read / write on byte array by QDataStream

Question

i have byte image array i want to write this byte array to another byte array with add some another value on second byte array , i'm using this code but i think something is wrong

 QByteArray byteArray;

 QDataStream ds(&byteArray,QIODevice::ReadWrite);

 ds<<(qint32)20;

 ds<<bArray;

 qint32 code;

 ds>>code;

when i trace ds>>code it is always have 0 value but in fact it must have 20 value and i used ds.resetStatus(); but it return 0 value again

Megidd · Accepted Answer · 2019-07-17 05:03:16Z

2

I suspect that QDataStream::operator<< functions sets some sort of pointer/iterator/index to point to the next location where they can start inserting data when the next call is made. QDataStream::operator>> probably starts to read from the same location.

QDataStream::resetStatus() does not change the position from where the object reads/writes. It merely resets the status to QDataStream::Ok to allow you to read from the stream after an error has occurred.

You can use two QDataStream objects -- one for writing to the QByteArray and the other for reading from the same QByteArray.

QByteArray byteArray;

QDataStream ds_w(&byteArray,QIODevice::WriteOnly);
QDataStream ds_r(&byteArray,QIODevice::ReadOnly);

ds_w << (qint32)20;

ds_w << bArray;

qint32 code;

ds_r >> code;

edited Jul 17, 2019 at 5:03

Megidd

8,22317 gold badges85 silver badges187 bronze badges

answered Jul 2, 2016 at 18:36

R Sahu

207k15 gold badges168 silver badges291 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

NetProjects Ir Over a year ago

ty R Sahu your codes worked too but i used ds.device()->reset();

Mike Over a year ago

note that you can use ds.device()->seek() to point to wherever you want (not just the beginning of the stream).

Collectives™ on Stack Overflow

read / write on byte array by QDataStream

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related