QBitArray Class Reference

The QBitArray class provides an array of bits. More...

#include <qbitarray.h>

Public Types
typedef QByteArray::DataPtr	DataPtr

Public Functions
bool	at (int i) const
	Returns the value of the bit at index position i. More...
void	clear ()
	Clears the contents of the bit array and makes it empty. More...
void	clearBit (int i)
	Sets the bit at index position i to 0. More...
int	count () const
	Same as size(). More...
int	count (bool on) const
	If on is true, this function returns the number of 1-bits stored in the bit array; otherwise the number of 0-bits is returned. More...
DataPtr &	data_ptr ()
void	detach ()
bool	fill (bool val, int size=-1)
	Sets every bit in the bit array to value, returning true if successful; otherwise returns false. More...
void	fill (bool val, int first, int last)
	Sets bits at index positions begin up to and excluding end to value. More...
bool	isDetached () const
bool	isEmpty () const
	Returns true if this bit array has size 0; otherwise returns false. More...
bool	isNull () const
	Returns true if this bit array is null; otherwise returns false. More...
QBitArray &	operator &= (const QBitArray &)
bool	operator!= (const QBitArray &a) const
	Returns true if other is not equal to this bit array; otherwise returns false. More...
QBitArray &	operator= (const QBitArray &other)
	Assigns other to this bit array and returns a reference to this bit array. More...
bool	operator== (const QBitArray &a) const
	Returns true if other is equal to this bit array; otherwise returns false. More...
QBitRef	operator[] (int i)
	Returns the bit at index position i as a modifiable reference. More...
bool	operator[] (int i) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
QBitRef	operator[] (uint i)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
bool	operator[] (uint i) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. More...
QBitArray &	operator^= (const QBitArray &)
	Performs the XOR operation between all bits in this bit array and other. More...
QBitArray &	operator|= (const QBitArray &)
	Performs the OR operation between all bits in this bit array and other. More...
QBitArray	operator~ () const
	Returns a bit array that contains the inverted bits of this bit array. More...
	QBitArray ()
	Constructs an empty bit array. More...
	QBitArray (int size, bool val=false)
	Constructs a bit array containing size bits. More...
	QBitArray (const QBitArray &other)
	Constructs a copy of other. More...
void	resize (int size)
	Resizes the bit array to size bits. More...
void	setBit (int i)
	Sets the bit at index position i to 1. More...
void	setBit (int i, bool val)
	Sets the bit at index position i to value. More...
int	size () const
	Returns the number of bits stored in the bit array. More...
void	swap (QBitArray &other)
	Swaps bit array other with this bit array. More...
bool	testBit (int i) const
	Returns true if the bit at index position i is 1; otherwise returns false. More...
bool	toggleBit (int i)
	Inverts the value of the bit at index position i, returning the previous value of that bit as either true (if it was set) or false (if it was unset). More...
void	truncate (int pos)
	Truncates the bit array at index position pos. More...

Properties
QByteArray	d

Friends
Q_CORE_EXPORT QDataStream &	operator<< (QDataStream &, const QBitArray &)
	Writes bit array ba to stream out. More...
Q_CORE_EXPORT QDataStream &	operator>> (QDataStream &, QBitArray &)
	Reads a bit array into ba from stream in. More...
Q_CORE_EXPORT uint	qHash (const QBitArray &key)

Related Functions
(Note that these are not member functions.)
QBitArray	operator& (const QBitArray &a1, const QBitArray &a2)
	Returns a bit array that is the AND of the bit arrays a1 and a2. More...
QBitArray	operator^ (const QBitArray &a1, const QBitArray &a2)
	Returns a bit array that is the XOR of the bit arrays a1 and a2. More...
QBitArray	operator| (const QBitArray &a1, const QBitArray &a2)
	Returns a bit array that is the OR of the bit arrays a1 and a2. More...

Detailed Description

The QBitArray class provides an array of bits.

Note

This class or function is reentrant.

A QBitArray is an array that gives access to individual bits and provides operators (AND, OR, XOR, and NOT) that work on entire arrays of bits. It uses implicit sharing (copy-on-write) to reduce memory usage and to avoid the needless copying of data.

The following code constructs a QBitArray containing 200 bits initialized to false (0):

QBitArray ba(200);

To initialize the bits to true, either pass true as second argument to the constructor, or call fill() later on.

QBitArray uses 0-based indexes, just like C++ arrays. To access the bit at a particular index position, you can use operator[](). On non-const bit arrays, operator[]() returns a reference to a bit that can be used on the left side of an assignment. For example:

QBitArray ba;
ba.resize(3);
ba[0] = true;

For technical reasons, it is more efficient to use testBit() and setBit() to access bits in the array than operator[](). For example:

QBitArray supports & (AND), | (OR), ^ (XOR), ~ (NOT), as well as &=, |=, and ^=. These operators work in the same way as the built-in C++ bitwise operators of the same name. For example:

QBitArray x(5);
x.setBit(3, true);
// x: [ 0, 0, 0, 1, 0 ]

QBitArray y(5);
y.setBit(4, true);
// y: [ 0, 0, 0, 0, 1 ]

x |= y;
// x: [ 0, 0, 0, 1, 1 ]

For historical reasons, QBitArray distinguishes between a null bit array and an empty bit array. A null bit array is a bit array that is initialized using QBitArray's default constructor. An empty bit array is any bit array with size 0. A null bit array is always empty, but an empty bit array isn't necessarily null:

QBitArray().isNull();           // returns true
QBitArray().isEmpty();          // returns true

QBitArray(0).isNull();          // returns false
QBitArray(0).isEmpty();         // returns true

QBitArray(3).isNull();          // returns false
QBitArray(3).isEmpty();         // returns false

All functions except isNull() treat null bit arrays the same as empty bit arrays; for example, QBitArray() compares equal to QBitArray(0). We recommend that you always use isEmpty() and avoid isNull().

See also

QByteArray, QVector

Definition at line 54 of file qbitarray.h.

Typedefs

DataPtr

QBitArray::DataPtr

Warning

This function is not part of the public interface.

Definition at line 113 of file qbitarray.h.

Constructors and Destructors

QBitArray() [1/3]

QBitArray::QBitArray ( )

inline

Constructs an empty bit array.

See also

isEmpty()

Definition at line 62 of file qbitarray.h.

{}

QBitArray() [2/3]

QBitArray::QBitArray ( int  size, bool  value = false  )

explicit

Constructs a bit array containing size bits.

The bits are initialized with value, which defaults to false (0).

Definition at line 129 of file qbitarray.cpp.

{
    if (!size) {
        d.resize(0);
        return;
    }
    d.resize(1 + (size+7)/8);
    uchar* c = reinterpret_cast<uchar*>(d.data());
    memset(c, value ? 0xff : 0, d.size());
    *c = d.size()*8 - size;
    if (value && size && size % 8)
        *(c+1+size/8) &= (1 << (size%8)) - 1;
}

QBitArray() [3/3]

QBitArray::QBitArray ( const QBitArray &  other )

inline

Constructs a copy of other.

This operation takes constant time, because QBitArray is implicitly shared. This makes returning a QBitArray from a function very fast. If a shared instance is modified, it will be copied (copy-on-write), and that takes linear time.

See also

operator=()

Definition at line 64 of file qbitarray.h.

: d(other.d) {}

Functions

at()

bool QBitArray::at ( int  i ) const

inline

Returns the value of the bit at index position i.

i must be a valid index position in the bit array (i.e., 0 <= i < size()).

See also

operator[]()

Definition at line 146 of file qbitarray.h.

Referenced by QHeaderViewPrivate::isVisualIndexHidden().

{ return testBit(i); }

clear()

void QBitArray::clear ( )

inline

Clears the contents of the bit array and makes it empty.

See also

resize(), isEmpty()

Definition at line 85 of file qbitarray.h.

Referenced by QXIMInputContext::ICData::clear(), and QHeaderViewPrivate::prepareSectionSelected().

{ d.clear(); }

clearBit()

void QBitArray::clearBit ( int  i )

inline

Sets the bit at index position i to 0.

i must be a valid index position in the bit array (i.e., 0 <= i < size()).

See also

setBit(), toggleBit()

Definition at line 132 of file qbitarray.h.

Referenced by QLCDNumberPrivate::internalSetString(), and xic_draw_callback().

{ Q_ASSERT(uint(i) < uint(size()));
 *(reinterpret_cast<uchar*>(d.data())+1+(i>>3)) &= ~uchar(1 << (i & 7)); }

count() [1/2]

int QBitArray::count ( ) const

inline

Same as size().

Definition at line 74 of file qbitarray.h.

Referenced by QHeaderViewPrivate::_q_layoutChanged(), QHeaderViewPrivate::prepareSectionSelected(), and QHeaderView::sectionsInserted().

{ return (d.size() << 3) - *d.constData(); }

count() [2/2]

int QBitArray::count

(

bool

on

)

const

If on is true, this function returns the number of 1-bits stored in the bit array; otherwise the number of 0-bits is returned.

Definition at line 166 of file qbitarray.cpp.

{
    int numBits = 0;
    int len = size();
#if 0
    for (int i = 0; i < len; ++i)
        numBits += testBit(i);
#else
    // See http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
    const quint8 *bits = reinterpret_cast<const quint8 *>(d.data()) + 1;
    while (len >= 32) {
        quint32 v = quint32(bits[0]) | (quint32(bits[1]) << 8) | (quint32(bits[2]) << 16) | (quint32(bits[3]) << 24);
        quint32 c = ((v & 0xfff) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        c += (((v & 0xfff000) >> 12) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        c += ((v >> 24) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        len -= 32;
        bits += 4;
        numBits += int(c);
    }
    while (len >= 24) {
        quint32 v = quint32(bits[0]) | (quint32(bits[1]) << 8) | (quint32(bits[2]) << 16);
        quint32 c =  ((v & 0xfff) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        c += (((v & 0xfff000) >> 12) * Q_UINT64_C(0x1001001001001) & Q_UINT64_C(0x84210842108421)) % 0x1f;
        len -= 24;
        bits += 3;
        numBits += int(c);
    }
    while (len >= 0) {
        if (bits[len / 8] & (1 << ((len - 1) & 7)))
            ++numBits;
        --len;
    }
#endif
    return on ? numBits : size() - numBits;
}

data_ptr()

DataPtr & QBitArray::data_ptr ( )

inline

Warning

This function is not part of the public interface.

Definition at line 114 of file qbitarray.h.

{ return d.data_ptr(); }

detach()

void QBitArray::detach ( )

inline

Warning

This function is not part of the public interface.

Definition at line 83 of file qbitarray.h.

{ d.detach(); }

fill() [1/2]

bool QBitArray::fill ( bool  value, int  size = -1  )

inline

Sets every bit in the bit array to value, returning true if successful; otherwise returns false.

If size is different from -1 (the default), the bit array is resized to size beforehand.

Example:

QBitArray ba(8);
ba.fill(true);
// ba: [ 1, 1, 1, 1, 1, 1, 1, 1 ]

ba.fill(false, 2);
// ba: [ 0, 0 ]

See also

resize()

Definition at line 117 of file qbitarray.h.

Referenced by QHeaderViewPrivate::prepareSectionSelected(), and QHeaderView::sectionsInserted().

{ *this = QBitArray((asize < 0 ? this->size() : asize), aval); return true; }

fill() [2/2]

void QBitArray::fill	(	bool	value,
		int	begin,
		int	end
	)

Sets bits at index positions begin up to and excluding end to value.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

begin and end must be a valid index position in the bit array (i.e., 0 <= begin <= size() and 0 <= end <= size()).

Definition at line 287 of file qbitarray.cpp.

{
    while (begin < end && begin & 0x7)
        setBit(begin++, value);
    int len = end - begin;
    if (len <= 0)
        return;
    int s = len & ~0x7;
    uchar *c = reinterpret_cast<uchar*>(d.data());
    memset(c + (begin >> 3) + 1, value ? 0xff : 0, s >> 3);
    begin += s;
    while (begin < end)
        setBit(begin++, value);
}

isDetached()

bool QBitArray::isDetached ( ) const

inline

Warning

This function is not part of the public interface.

Definition at line 84 of file qbitarray.h.

{ return d.isDetached(); }

isEmpty()

bool QBitArray::isEmpty ( ) const

inline

Returns true if this bit array has size 0; otherwise returns false.

See also

size()

Definition at line 78 of file qbitarray.h.

Referenced by QHeaderViewPrivate::isVisualIndexHidden(), QDeclarativeVMEMetaObject::metaCall(), QHeaderView::moveSection(), QDeclarativeVMEMetaObject::registerInterceptor(), and QHeaderViewPrivate::setVisualIndexHidden().

{ return d.isEmpty(); }

isNull()

bool QBitArray::isNull ( ) const

inline

Returns true if this bit array is null; otherwise returns false.

Example:

QBitArray().isNull();           // returns true
QBitArray(0).isNull();          // returns false
QBitArray(3).isNull();          // returns false

Qt makes a distinction between null bit arrays and empty bit arrays for historical reasons. For most applications, what matters is whether or not a bit array contains any data, and this can be determined using isEmpty().

See also

isEmpty()

Definition at line 79 of file qbitarray.h.

{ return d.isNull(); }

operator &=()

QBitArray& QBitArray::operator&=

(

const QBitArray &

)

Referenced by fill().

operator!=()

bool QBitArray::operator!= ( const QBitArray &  other ) const

inline

Returns true if other is not equal to this bit array; otherwise returns false.

See also

operator==()

Definition at line 105 of file qbitarray.h.

{ return d != a.d; }

operator=()

QBitArray & QBitArray::operator= ( const QBitArray &  other )

inline

Assigns other to this bit array and returns a reference to this bit array.

Definition at line 65 of file qbitarray.h.

{ d = other.d; return *this; }

operator==()

bool QBitArray::operator== ( const QBitArray &  other ) const

inline

Returns true if other is equal to this bit array; otherwise returns false.

See also

operator!=()

Definition at line 104 of file qbitarray.h.

{ return d == a.d; }

operator[]() [1/4]

QBitRef QBitArray::operator[] ( int  i )

inline

Returns the bit at index position i as a modifiable reference.

i must be a valid index position in the bit array (i.e., 0 <= i < size()).

Example:

QBitArray a(3);
a[0] = false;
a[1] = true;
a[2] = a[0] ^ a[1];

The return value is of type QBitRef, a helper class for QBitArray. When you get an object of type QBitRef, you can assign to it, and the assignment will apply to the bit in the QBitArray from which you got the reference.

The functions testBit(), setBit(), and clearBit() are slightly faster.

See also

at(), testBit(), setBit(), clearBit()

Definition at line 162 of file qbitarray.h.

{ Q_ASSERT(i >= 0); return QBitRef(*this, i); }

operator[]() [2/4]

bool QBitArray::operator[] ( int  i ) const

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 144 of file qbitarray.h.

{ return testBit(i); }

operator[]() [3/4]

QBitRef QBitArray::operator[] ( uint  i )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 164 of file qbitarray.h.

{ return QBitRef(*this, i); }

operator[]() [4/4]

bool QBitArray::operator[] ( uint  i ) const

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 145 of file qbitarray.h.

{ return testBit(i); }

operator^=()

QBitArray & QBitArray::operator^=

(

const QBitArray &

other

)

Performs the XOR operation between all bits in this bit array and other.

Assigns the result to this bit array, and returns a reference to it.

The result has the length of the longest of the two bit arrays, with any missing bits (if one array is shorter than the other) taken to be 0.

Example:

QBitArray a(3);
QBitArray b(2);
a[0] = 1; a[1] = 0; a[2] = 1;   // a: [ 1, 0, 1 ]
b[0] = 1; b[1] = 0;             // b: [ 1, 1 ]
a ^= b;                         // a: [ 0, 1, 1 ]

See also

operator^(), operator&=(), operator|=(), operator~()

Definition at line 580 of file qbitarray.cpp.

{
    resize(qMax(size(), other.size()));
    uchar *a1 = reinterpret_cast<uchar*>(d.data()) + 1;
    const uchar *a2 = reinterpret_cast<const uchar *>(other.d.constData()) + 1;
    int n = other.d.size() - 1;
    while (n-- > 0)
        *a1++ ^= *a2++;
    return *this;
}

operator|=()

QBitArray & QBitArray::operator|=

(

const QBitArray &

other

)

Performs the OR operation between all bits in this bit array and other.

Assigns the result to this bit array, and returns a reference to it.

The result has the length of the longest of the two bit arrays, with any missing bits (if one array is shorter than the other) taken to be 0.

Example:

QBitArray a(3);
QBitArray b(2);
a[0] = 1; a[1] = 0; a[2] = 1;   // a: [ 1, 0, 1 ]
b[0] = 1; b[1] = 0;             // b: [ 1, 1 ]
a |= b;                         // a: [ 1, 1, 1 ]

See also

operator|(), operator&=(), operator^=(), operator~()

Definition at line 554 of file qbitarray.cpp.

{
    resize(qMax(size(), other.size()));
    uchar *a1 = reinterpret_cast<uchar*>(d.data()) + 1;
    const uchar *a2 = reinterpret_cast<const uchar *>(other.d.constData()) + 1;
    int n = other.d.size() - 1;
    while (n-- > 0)
        *a1++ |= *a2++;
    return *this;
}

operator~()

QBitArray QBitArray::operator~

(

)

const

Returns a bit array that contains the inverted bits of this bit array.

Example:

QBitArray a(3);
QBitArray b;
a[0] = 1; a[1] = 0; a[2] = 1;   // a: [ 1, 0, 1 ]
b = ~a;                         // b: [ 0, 1, 0 ]

See also

operator&(), operator|(), operator^()

Definition at line 601 of file qbitarray.cpp.

{
    int sz = size();
    QBitArray a(sz);
    const uchar *a1 = reinterpret_cast<const uchar *>(d.constData()) + 1;
    uchar *a2 = reinterpret_cast<uchar*>(a.d.data()) + 1;
    int n = d.size() - 1;

    while (n-- > 0)
        *a2++ = ~*a1++;

    if (sz && sz%8)
        *(a2-1) &= (1 << (sz%8)) - 1;
    return a;
}

resize()

void QBitArray::resize

(

int

size

)

Resizes the bit array to size bits.

If size is greater than the current size, the bit array is extended to make it size bits with the extra bits added to the end. The new bits are initialized to false (0).

If size is less than the current size, bits are removed from the end.

See also

size()

Definition at line 214 of file qbitarray.cpp.

Referenced by QAbstractItemModel::decodeData(), QStandardItemModel::dropMimeData(), fill(), operator^=(), operator|=(), QDeclarativeVMEMetaObject::QDeclarativeVMEMetaObject(), QDeclarativeVMEMetaObject::registerInterceptor(), registerInterface(), registerType(), QHeaderView::sectionsInserted(), and xic_draw_callback().

{
    if (!size) {
        d.resize(0);
    } else {
        int s = d.size();
        d.resize(1 + (size+7)/8);
        uchar* c = reinterpret_cast<uchar*>(d.data());
        if (size > (s << 3))
            memset(c + s, 0, d.size() - s);
        else if ( size % 8)
            *(c+1+size/8) &= (1 << (size%8)) - 1;
        *c = d.size()*8 - size;
    }
}

setBit() [1/2]

void QBitArray::setBit ( int  i )

inline

Sets the bit at index position i to 1.

i must be a valid index position in the bit array (i.e., 0 <= i < size()).

See also

clearBit(), toggleBit()

Definition at line 128 of file qbitarray.h.

Referenced by QHeaderViewPrivate::_q_layoutChanged(), QDeclarativeVMEMetaObject::connectAlias(), QAbstractItemModel::decodeData(), QTableViewPrivate::drawAndClipSpans(), QStandardItemModel::dropMimeData(), fill(), QGridLayoutEngine::fillRowData(), QLCDNumberPrivate::internalSetString(), QRegExpMatchState::matchHere(), QHeaderView::moveSection(), QBitRef::operator=(), QTableView::paintEvent(), QDeclarativeVMEMetaObject::registerInterceptor(), registerInterface(), registerType(), QHeaderView::sectionsInserted(), QHeaderViewPrivate::setVisualIndexHidden(), and xic_draw_callback().

{ Q_ASSERT(uint(i) < uint(size()));
 *(reinterpret_cast<uchar*>(d.data())+1+(i>>3)) |= uchar(1 << (i & 7)); }

setBit() [2/2]

void QBitArray::setBit ( int  i, bool  value  )

inline

Sets the bit at index position i to value.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 136 of file qbitarray.h.

{ if (val) setBit(i); else clearBit(i); }

size()

int QBitArray::size ( ) const

inline

Returns the number of bits stored in the bit array.

See also

resize()

Definition at line 73 of file qbitarray.h.

Referenced by count(), fill(), QDeclarativeMetaType::isInterface(), QDeclarativeMetaType::isList(), QDeclarativeMetaType::isQObject(), operator^=(), operator|=(), operator~(), QTableView::paintEvent(), QBitArray(), qHash(), registerInterface(), registerType(), resize(), and xic_draw_callback().

{ return (d.size() << 3) - *d.constData(); }

swap()

void QBitArray::swap ( QBitArray &  other )

inline

Swaps bit array other with this bit array.

Since

4.8

This operation is very fast and never fails.

Definition at line 71 of file qbitarray.h.

{ qSwap(d, other.d); }

testBit()

bool QBitArray::testBit ( int  i ) const

inline

Returns true if the bit at index position i is 1; otherwise returns false.

i must be a valid index position in the bit array (i.e., 0 <= i < size()).

See also

setBit(), clearBit()

Definition at line 124 of file qbitarray.h.

Referenced by QHeaderViewPrivate::_q_layoutChanged(), QDeclarativeVMEMetaObject::connectAlias(), count(), QAbstractItemModel::decodeData(), QLCDNumberPrivate::drawString(), QStandardItemModel::dropMimeData(), QGridLayoutEngine::fillRowData(), QLCDNumberPrivate::internalSetString(), QDeclarativeMetaType::isInterface(), QDeclarativeMetaType::isList(), QDeclarativeMetaType::isQObject(), QRegExpMatchState::matchHere(), QDeclarativeVMEMetaObject::metaCall(), QHeaderView::moveSection(), QBitRef::operator bool(), QBitRef::operator!(), QTableView::paintEvent(), QLCDNumber::setDigitCount(), QDeclarativeMetaType::typeCategory(), and xic_draw_callback().

{ Q_ASSERT(uint(i) < uint(size()));
 return (*(reinterpret_cast<const uchar*>(d.constData())+1+(i>>3)) & (1 << (i & 7))) != 0; }

toggleBit()

bool QBitArray::toggleBit ( int  i )

inline

Inverts the value of the bit at index position i, returning the previous value of that bit as either true (if it was set) or false (if it was unset).

If the previous value was 0, the new value will be 1. If the previous value was 1, the new value will be 0.

i must be a valid index position in the bit array (i.e., 0 <= i < size()).

See also

setBit(), clearBit()

Definition at line 139 of file qbitarray.h.

{ Q_ASSERT(uint(i) < uint(size()));
 uchar b = uchar(1<<(i&7)); uchar* p = reinterpret_cast<uchar*>(d.data())+1+(i>>3);
 uchar c = uchar(*p&b); *p^=b; return c!=0; }

truncate()

void QBitArray::truncate ( int  pos )

inline

Truncates the bit array at index position pos.

If pos is beyond the end of the array, nothing happens.

See also

resize()

Definition at line 110 of file qbitarray.h.

{ if (pos < size()) resize(pos); }

Friends and Related Functions

operator&()

QBitArray operator & ( const QBitArray &  a1, const QBitArray &  a2  )

related

Returns a bit array that is the AND of the bit arrays a1 and a2.

The result has the length of the longest of the two bit arrays, with any missing bits (if one array is shorter than the other) taken to be 0.

Example:

QBitArray a(3);
QBitArray b(2);
QBitArray c;
a[0] = 1; a[1] = 0; a[2] = 1;   // a: [ 1, 0, 1 ]
b[0] = 1; b[1] = 0;             // b: [ 1, 1 ]
c = a & b;                      // c: [ 1, 0, 0 ]

See also

QBitArray::operator&=(), operator|(), operator^()

Definition at line 636 of file qbitarray.cpp.

{
    QBitArray tmp = a1;
    tmp &= a2;
    return tmp;
}

operator<<

QDataStream & operator<< ( QDataStream &  out, const QBitArray &  ba  )

friend

Writes bit array ba to stream out.

See also

Format of the QDataStream operators

Definition at line 767 of file qbitarray.cpp.

{
    quint32 len = ba.size();
    out << len;
    if (len > 0)
        out.writeRawData(ba.d.constData() + 1, ba.d.size() - 1);
    return out;
}

operator>>

QDataStream & operator>> ( QDataStream &  in, QBitArray &  ba  )

friend

Reads a bit array into ba from stream in.

See also

Format of the QDataStream operators

Definition at line 787 of file qbitarray.cpp.

{
    ba.clear();
    quint32 len;
    in >> len;
    if (len == 0) {
    ba.clear();
    return in;
    }

    const quint32 Step = 8 * 1024 * 1024;
    quint32 totalBytes = (len + 7) / 8;
    quint32 allocated = 0;

    while (allocated < totalBytes) {
        int blockSize = qMin(Step, totalBytes - allocated);
        ba.d.resize(allocated + blockSize + 1);
        if (in.readRawData(ba.d.data() + 1 + allocated, blockSize) != blockSize) {
            ba.clear();
            in.setStatus(QDataStream::ReadPastEnd);
            return in;
        }
        allocated += blockSize;
    }

    int paddingMask = ~((0x1 << (len & 0x7)) - 1);
    if (paddingMask != ~0x0 && (ba.d.constData()[ba.d.size() - 1] & paddingMask)) {
        ba.clear();
        in.setStatus(QDataStream::ReadCorruptData);
        return in;
    }

    *ba.d.data() = ba.d.size() * 8 - len;
    return in;
}

operator^()

QBitArray operator^ ( const QBitArray &  a1, const QBitArray &  a2  )

related

Returns a bit array that is the XOR of the bit arrays a1 and a2.

The result has the length of the longest of the two bit arrays, with any missing bits (if one array is shorter than the other) taken to be 0.

Example:

QBitArray a(3);
QBitArray b(2);
QBitArray c;
a[0] = 1; a[1] = 0; a[2] = 1;   // a: [ 1, 0, 1 ]
b[0] = 1; b[1] = 0;             // b: [ 1, 1 ]
c = a ^ b;                      // c: [ 0, 1, 1 ]

See also

QBitArray::operator^=(), operator&(), operator|()

Definition at line 688 of file qbitarray.cpp.

{
    QBitArray tmp = a1;
    tmp ^= a2;
    return tmp;
}

operator|()

QBitArray operator| ( const QBitArray &  a1, const QBitArray &  a2  )

related

Returns a bit array that is the OR of the bit arrays a1 and a2.

The result has the length of the longest of the two bit arrays, with any missing bits (if one array is shorter than the other) taken to be 0.

Example:

QBitArray a(3);
QBitArray b(2);
QBitArray c;
a[0] = 1; a[1] = 0; a[2] = 1;   // a: [ 1, 0, 1 ]
b[0] = 1; b[1] = 0;             // b: [ 1, 1 ]
c = a | b;                      // c: [ 1, 1, 1 ]

See also

QBitArray::operator|=(), operator&(), operator^()

Definition at line 662 of file qbitarray.cpp.

Referenced by QRect::QRect().

{
    QBitArray tmp = a1;
    tmp |= a2;
    return tmp;
}

qHash

Q_CORE_EXPORT uint qHash ( const QBitArray &  key )

friend

Definition at line 107 of file qhash.cpp.

{
    int m = bitArray.d.size() - 1;
    uint result = hash(reinterpret_cast<const uchar *>(bitArray.d.constData()), qMax(0, m));

    // deal with the last 0 to 7 bits manually, because we can't trust that
    // the padding is initialized to 0 in bitArray.d
    int n = bitArray.size();
    if (n & 0x7)
        result = ((result << 4) + bitArray.d.at(m)) & ((1 << n) - 1);
    return result;
}

Properties

d

QByteArray QBitArray::d

private

Definition at line 59 of file qbitarray.h.

Referenced by count(), fill(), operator!=(), operator=(), operator==(), operator^=(), operator|=(), operator~(), QBitArray(), qHash(), resize(), and swap().

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The documentation for this class was generated from the following files:

• /src/corelib/tools/qbitarray.h
• /src/corelib/tools/qbitarray.cpp