Is it possible to move data from a QByteArray

t3685

Hi,

I am working on a client-server program over tcp and need to process a lot of raw byte data. Using Qt sockets I send and receive my data as QByteArray's. However to parse data I need to copy the data into another parsing class that is written by someone else. However their API also accept pre-allocated char* arrays and since I don't plan to use my QByteArrays again I thought it might be more efficient to just move the data out of the QByteArray, thereby eliminating one needless copy. Is this possible?

Thanks in advance!

SGaist

Hi,

Why not directly pass the data from the QByteArray using "this":http://qt-project.org/doc/qt-4.8/qbytearray.html#data ?

t3685

Thanks for your reply.

I'm using that right now (actually const data()), but the parsing class will then take a copy of the data. I would like to take ownership of the data inside the QByteArray, in which case I can just pass ownership to the parsing class. Is this possible?

SGaist

Just to be sure: what options does this library offer to parse your data ? And how do they work memory handling wise ?

ChrisW67

No, it is not possible to take ownership of the memory block you are given by data()/const_data().

If the parsing routine takes a copy of the (presumably \0 terminated) memory you pass as its const char * argument then it will do that regardless of whether you "own" that memory or the QByteArray does.

t3685

The parsing class gives me two options: either take a copy of the data (via a pointer) or pass a pointer and the parsing class will take ownership. But it seems that it is not possible to pass ownership, thanks for your answer.

SGaist

It would really be useful to know what the library authors mean by "take ownership"

t3685

As in you give them a pointer and they will delete it once it's done, without copying.

SGaist

Then indeed, you can't give them the QByteArray data to delete