The QBitArray class provides an array of bits. 更多...
| 头： | #include <QBitArray> |
| CMake: |
find_package(Qt6 REQUIRED COMPONENTS Core)
target_link_libraries(mytarget PRIVATE Qt6::Core) |
| qmake: | QT += core |
注意： 此类的所有函数 可重入 .
| QBitArray () | |
| QBitArray (qsizetype size , bool value = false) | |
| QBitArray (const QBitArray & other ) | |
| QBitArray (QBitArray && other ) | |
| bool | at (qsizetype i ) const |
| const char * | bits () const |
| void | clear () |
| void | clearBit (qsizetype i ) |
| qsizetype | count () const |
| qsizetype | count (bool on ) const |
| bool | fill (bool value , qsizetype size = -1) |
| void | fill (bool value , qsizetype begin , qsizetype end ) |
| bool | isEmpty () const |
| bool | isNull () const |
| void | resize (qsizetype size ) |
| void | setBit (qsizetype i ) |
| void | setBit (qsizetype i , bool value ) |
| qsizetype | size () const |
| void | swap (QBitArray & other ) |
| bool | testBit (qsizetype i ) const |
| quint32 | toUInt32 (QSysInfo::Endian endianness , bool * ok = nullptr) const |
| bool | toggleBit (qsizetype i ) |
| void | truncate (qsizetype pos ) |
| 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[] (qsizetype i ) |
| bool | operator[] (qsizetype i ) const |
| QBitArray & | operator^= (const QBitArray & other ) |
| QBitArray & | operator|= (const QBitArray & other ) |
| QBitArray | operator~ () const |
| QBitArray | fromBits (const char * data , qsizetype size ) |
| QBitArray | operator& (const QBitArray & a1 , const QBitArray & a2 ) |
| QDataStream & | operator<< (QDataStream & out , const QBitArray & ba ) |
| QDataStream & | operator>> (QDataStream & in , QBitArray & ba ) |
| QBitArray | operator^ (const QBitArray & a1 , const QBitArray & a2 ) |
| QBitArray | operator| (const QBitArray & a1 , const QBitArray & a2 ) |
A QBitArray is an array that gives access to individual bits and provides operators ( AND , OR , XOR ，和 NOT ) that work on entire arrays of bits. It uses 隐式共享 (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; ba[1] = false; ba[2] = true;
For technical reasons, it is more efficient to use testBit () 和 setBit () to access bits in the array than operator[](). For example:
QBitArray ba(3); ba.setBit(0, true); ba.setBit(1, false); ba.setBit(2, true);
QBitArray supports
&
(
AND
),
|
(
OR
),
^
(
XOR
),
~
(
NOT
), as well as
&=
,
|=
，和
^=
. 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
所有函数除了 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 ().
另请参阅 QByteArray and QList .
Constructs an empty bit array.
另请参阅 isEmpty ().
[explicit]
QBitArray::
QBitArray
(
qsizetype
size
,
bool
value
= false)
Constructs a bit array containing size bits. The bits are initialized with value , which defaults to false (0).
构造副本为 other .
此操作花费 常量时间 , because QBitArray is 隐式共享 . 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 线性时间 .
另请参阅 operator= ().
Move-constructs a QBitArray instance, making it point at the same object that other 所指向的。
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 ()).
另请参阅 operator[] ().
Returns a pointer to a dense bit array for this
QBitArray
. Bits are counted upwards from the least significant bit in each byte. The number of bits relevant in the last byte is given by
size() % 8
.
Clears the contents of the bit array and makes it empty.
Sets the bit at index position i 为 0。
i must be a valid index position in the bit array (i.e., 0 <= i < size ()).
另请参阅 setBit () 和 toggleBit ().
如同 size ().
若 on is true, this function returns the number of 1-bits stored in the bit array; otherwise the number of 0-bits is returned.
Sets every bit in the bit array to
value
, returning true if successful; otherwise returns
false
。若
size
is different from -1 (the default), the bit array is resized to
size
事先。
范例：
QBitArray ba(8); ba.fill(true); // ba: [ 1, 1, 1, 1, 1, 1, 1, 1 ] ba.fill(false, 2); // ba: [ 0, 0 ]
另请参阅 resize ().
这是重载函数。
Sets bits at index positions begin up to (but not including) end to value .
begin must be a valid index position in the bit array (0 <= begin < size ()).
end must be either a valid index position or equal to size (), in which case the fill operation runs until the end of the array (0 <= end <= size ()).
范例：
QBitArray ba(4); ba.fill(true, 1, 2); // ba: [ 0, 1, 0, 0 ] ba.fill(true, 1, 3); // ba: [ 0, 1, 1, 0 ] ba.fill(true, 1, 4); // ba: [ 0, 1, 1, 1 ]
[static]
QBitArray
QBitArray::
fromBits
(const
char
*
data
,
qsizetype
size
)
创建 QBitArray with the dense bit array located at data ，采用 size bits. The byte array at data 必须至少 size / 8 (rounded up) bytes long.
若 size is not a multiple of 8, this function will include the lowest size % 8 bits from the last byte in data .
另请参阅 bits ().
返回
true
if this bit array has size 0; otherwise returns false.
另请参阅 size ().
返回
true
if this bit array is null; otherwise returns
false
.
范例：
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 ().
另请参阅 isEmpty ().
Resizes the bit array to size 位。
若 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).
若 size is less than the current size, bits are removed from the end.
另请参阅 size ().
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 ()).
另请参阅 clearBit () 和 toggleBit ().
这是重载函数。
Sets the bit at index position i to value .
Returns the number of bits stored in the bit array.
另请参阅 resize ().
Swaps bit array other with this bit array. This operation is very fast and never fails.
返回
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 ()).
[since 6.0]
quint32
QBitArray::
toUInt32
(
QSysInfo::Endian
endianness
,
bool
*
ok
= nullptr) const
Returns the array of bit converted to an int. The conversion is based on
endianness
. Converts up to the first 32 bits of the array to
quint32
and returns it, obeying
endianness
。若
ok
is not a null pointer, and the array has more than 32 bits,
ok
is set to false and this function returns zero; otherwise, it's set to true.
该函数在 Qt 6.0 引入。
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 ()).
Truncates the bit array at index position pos .
若 pos 超越数组末尾，什么都不发生。
另请参阅 resize ().
返回
true
if
other
is not equal to this bit array; otherwise returns
false
.
另请参阅 operator== ().
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.
范例：
QBitArray a(3); QBitArray b(2); a[0] = 1; a[1] = 0; a[2] = 1; // a: [ 1, 0, 1 ] b[0] = 1; b[1] = 1; // b: [ 1, 1 ] a &= b; // a: [ 1, 0, 0 ]
另请参阅 operator& (), operator|= (), operator^= ()，和 operator~ ().
赋值 other to this bit array and returns a reference to this bit array.
移动 other to this bit array and returns a reference to this bit array.
返回
true
if
other
is equal to this bit array; otherwise returns
false
.
另请参阅 operator!= ().
Returns the bit at index position i 作为可修改引用。
i must be a valid index position in the bit array (i.e., 0 <= i < size ()).
范例：
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.
函数 testBit (), setBit ()，和 clearBit () are slightly faster.
另请参阅 at (), testBit (), setBit ()，和 clearBit ().
这是重载函数。
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.
范例：
QBitArray a(3); QBitArray b(2); a[0] = 1; a[1] = 0; a[2] = 1; // a: [ 1, 0, 1 ] b[0] = 1; b[1] = 1; // b: [ 1, 1 ] a ^= b; // a: [ 0, 1, 1 ]
另请参阅 operator^ (), operator&= (), operator|= ()，和 operator~ ().
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.
范例：
QBitArray a(3); QBitArray b(2); a[0] = 1; a[1] = 0; a[2] = 1; // a: [ 1, 0, 1 ] b[0] = 1; b[1] = 1; // b: [ 1, 1 ] a |= b; // a: [ 1, 1, 1 ]
另请参阅 operator| (), operator&= (), operator^= ()，和 operator~ ().
Returns a bit array that contains the inverted bits of this bit array.
范例：
QBitArray a(3); QBitArray b; a[0] = 1; a[1] = 0; a[2] = 1; // a: [ 1, 0, 1 ] b = ~a; // b: [ 0, 1, 0 ]
另请参阅 operator& (), operator| ()，和 operator^ ().
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.
范例：
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] = 1; // b: [ 1, 1 ] c = a & b; // c: [ 1, 0, 0 ]
另请参阅 operator&= (), operator| ()，和 operator^ ().
Writes bit array ba 到流 out .
另请参阅 QDataStream 运算符格式 .
Reads a bit array into ba from stream in .
另请参阅 QDataStream 运算符格式 .
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.
范例：
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] = 1; // b: [ 1, 1 ] c = a ^ b; // c: [ 0, 1, 1 ]
另请参阅 operator^=() , operator&() ，和 operator|() .
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.
范例：
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] = 1; // b: [ 1, 1 ] c = a | b; // c: [ 1, 1, 1 ]
另请参阅 QBitArray::operator|= (), operator& ()，和 operator^ ().