Stores an array of bits. More...

Public Methods
	QBitArray ()

	QBitArray (const QBitArray &other)

	QBitArray (int size, bool value=false)

bool	at (int i) const

void	clear ()

void	clearBit (int i)

int	count () const

int	count (bool on) const

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

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

bool	isEmpty () const

bool	isNull () const

bool	operator!= (const QBitArray &other) const

QBitArray &	operator&= (const QBitArray &other)

QBitArray &	operator= (const QBitArray &other)

QBitArray &	operator= (QBitArray &&other)

bool	operator== (const QBitArray &other) const

QBitRef	operator[] (int i)

bool	operator[] (int i) const

QBitRef	operator[] (uint i)

bool	operator[] (uint i) const

QBitArray &	operator^= (const QBitArray &other)

QBitArray &	operator\|= (const QBitArray &other)

QBitArray	operator~ () const

void	resize (int size)

void	setBit (int i)

void	setBit (int i, bool value)

int	size () const

void	swap (QBitArray &other)

bool	testBit (int i) const

bool	toggleBit (int i)

void	truncate (int pos)

Friends
QDataStream &	operator<< (QDataStream &stream, const QBitArray &bitArray)

QDataStream &	operator>> (QDataStream &stream, QBitArray &bitArray)

Related Functions
These are not member functions
QBitArray	operator& (const QBitArray &a1, const QBitArray &a2)

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

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

Detailed Description

The QBitArray class stores an array of bits which provides access to individual bits and 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. 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.

QBitArray ba;
ba.resize(3);
 
ba[0] = true;
ba[1] = false;
ba[2] = true;

It is more efficient to use testBit() and setBit() to access bits in the array than operator[]().

QBitArray ba(3);
ba.setBit(0, true);
ba.setBit(1, false);
ba.setBit(2, true);

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.

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 ]

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 however an empty bit array is not 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

The only method which distinguishes between null and empty is isNull(). For example, QBitArray() compares equal to QBitArray(0). You should normally use isEmpty() instead of isNull().

See also: QByteArray, QVector

Constructor & Destructor Documentation

QBitArray::QBitArray ( )

inline

Constructs an empty bit array.

See also: isEmpty()

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).

QBitArray::QBitArray ( const QBitArray & other )

inline

Copy constructs a new QBitArray from 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=()

Method Documentation

bool QBitArray::at ( int i ) const

inline

Returns the value of the bit at index position i. The value for i must be a valid index position in the bit array.

See also: operator[]()

void QBitArray::clear ( )

inline

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

See also: resize(), isEmpty()

void QBitArray::clearBit ( int i )

inline

Sets the bit at index position i to 0. The value for i must be a valid index position in the bit array.

See also: setBit(), toggleBit()

int QBitArray::count ( ) const

inline

Equivalent to calling size().

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.

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

Sets bits at index positions begin up to and excluding end to value. The value for begin and end must be valid index positions in the bit array.

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 bit array is resized to the value of size beforehand.

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()

bool QBitArray::isEmpty ( ) const

inline

Returns true if this bit array has a size of 0, otherwise returns false.

See also: size()

bool QBitArray::isNull ( ) const

inline

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

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

CopperSpice makes a distinction between null bit arrays and empty bit arrays. 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()

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==()

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

Performs the AND 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.

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, 0, 0 ]

See also: operator&(), operator|=(), operator^=(), operator~()

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

inline

Copy assigns from other and returns a reference to this object.

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

inline

Move assigns from other and returns a reference to this object.

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

inline

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

See also: operator!=()

QBitRef QBitArray::operator[] ( int i )

inline

Returns a reference to the data at index position i. The value for i must be a valid index position in the bit array.

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.

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

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

See also: at(), testBit(), setBit(), clearBit()

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

inline

Refer to operator[]().

QBitRef QBitArray::operator[] ( uint i )

inline

Refer to operator[]().

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

inline

Refer to 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.

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~()

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.

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~()

QBitArray QBitArray::operator~ ( ) const

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

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^()

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()

void QBitArray::setBit ( int i )

inline

Sets the bit at index position i to 1. The value for i must be a valid index position in the bit array.

See also: clearBit(), toggleBit()

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

inline

Sets the bit at index position i to value.

int QBitArray::size ( ) const

inline

Returns the number of bits stored in the bit array.

See also: resize()

void QBitArray::swap ( QBitArray & other )

inline

Swaps other with this object. This operation is very fast and never fails.

bool QBitArray::testBit ( int i ) const

inline

Returns true if the bit at index position i is 1, otherwise returns false. The value for i must be a valid index position in the bit array.

See also: setBit(), clearBit()

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). The value for i must be a valid index position in the bit array.

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

See also: setBit(), clearBit()

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()

Friends And Related Function Documentation

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

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.

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

QDataStream & operator<<	(	QDataStream &	stream,
		const QBitArray &	bitArray
	)

friend

Writes the given bitArray to the stream. Returns a reference to the stream.

Refer to Serializing Data Types for additional information.

QDataStream & operator>>	(	QDataStream &	stream,
		QBitArray &	bitArray
	)

friend

Reads from the stream into the given bitArray. Returns a reference to the stream.

Refer to Serializing Data Types for additional information.

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

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.

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|()

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

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.

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^()

Public Methods

Friends

Related Functions

Detailed Description

Constructor & Destructor Documentation

Method Documentation

Friends And Related Function Documentation