QbyteArray data copy

Question

I have two QByteArray, sData and dData.

I want to copy n bytes from location x in dData i.e. &dData[x] to location y of sData i.e. &sData[y].

In C, array copy is done by memcpy(&dData[x], &sData[y], n);

How could copying above data of QByteArray be done in Qt?

Answer 1

From the Qt documentation, you can use the replace function: -

QByteArray & QByteArray::replace(int pos, int len, const QByteArray & after)

Replaces len bytes from index position pos with the byte array after, and returns a reference to this byte array.

So, using the overload

QByteArray & QByteArray::replace(int pos, int len, const char * after);

sData = sData.replace(y, nBytes, dData.constData()+x);

Answer 2

Besides the given answer you could also use memcpy and the QByteArray::data() member to get a pointer to the internal array. Of course you are then responsible that the size of the destination array is big enough to hold all copied data from the source array.

memcpy(dest.data() + y, src.constData() + x, n)

Answer 3

If you want to copy data from index zero, there is a function for that:

sData.setRawData(dData, n);