qt - How can I convert integer to qbitarray?

Question

How can I get QBitArray from qint value? I need to change some bits in number, so I want to use QBitArray for it.

Answer 1

QBitArray's '>>' operator expects bitset size as the first 4 bytes, so JustMaximumPower's snipper won't work. Correct data stream should look like this:

QBitArray bits;

quint32 size = 32;
quint32 value = 1337;
QByteArray data;
QDataStream stream(data, QIODevice::ReadWrite);
stream << size << value;
stream.device()->seek(0);
stream >> bits;

Actually I don't find QBitArray very useful. You could try std::vector<bool> for variable size or std::bitset for fixed size (both from STL library).

std::bitset<32> bits(1337);
bits[0] = 1;

Answer 2

Not testet but should work:

qint value = 1337;
QBitArray bits;
QDataStream stream;

stream << value;
bits << stream;

Answer 3

If you want to just change some bits, QBitArray is overkill.

int bitmask = 1 << 3; // let's change 4th bit
bitmask = 0x55555555; // or perhaps all odd bits

int number = 12345678;
number |= bitmask; // set to 1s
number &= ~bitmask; // set to 0s
number ^= bitmask; // negate what's already there