QBitArray ¶

概要 ¶

详细描述 ¶

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):

ba = QBitArray(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:

ba = QBitArray()
ba.resize(3)
ba[0] = True
ba[1] = False
ba[2] = True
											

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

ba = QBitArray(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:

x = QBitArray(5)
x.setBit(3, True)
# x: [ 0, 0, 0, 1, 0 ]
y = QBitArray(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() .

另请参阅

QByteArray QVector

class QBitArray ¶

QBitArray(other)

QBitArray(size[, val=false])

param size

int

param other

QBitArray

param val

bool

Constructs an empty bit array.

另请参阅

isEmpty()

Constructs a bit array containing size bits. The bits are initialized with value , which defaults to false (0).

PySide2.QtCore.QBitArray. __getitem__ ( ) ¶

PySide2.QtCore.QBitArray. __len__ ( ) ¶

PySide2.QtCore.QBitArray. __setitem__ ( ) ¶

PySide2.QtCore.QBitArray. at ( i ) ¶

参数

i – int

返回类型

bool

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[]()

PySide2.QtCore.QBitArray. bits ( ) ¶

返回类型

str

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 .

另请参阅

fromBits() size()

PySide2.QtCore.QBitArray. clear ( ) ¶

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

另请参阅

resize() isEmpty()

PySide2.QtCore.QBitArray. clearBit ( i ) ¶

参数

i – int

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() ).

另请参阅

setBit() toggleBit()

PySide2.QtCore.QBitArray. count ( ) ¶

返回类型

int

如同 size() .

PySide2.QtCore.QBitArray. count ( on ) ¶

参数

on – bool

返回类型

int

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.

PySide2.QtCore.QBitArray. fill ( val , first , last ) ¶

参数

• val – bool

• first – int

• last – int

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 ]
											

PySide2.QtCore.QBitArray. fill ( val [ , size=-1 ] ) ¶

参数

• val – bool

• size – int

返回类型

bool

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 beforehand.

范例：

ba = QBitArray(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()

static PySide2.QtCore.QBitArray. fromBits ( data , len ) ¶

参数

• data – str

• len – long long

返回类型

QBitArray

创建 QBitArray with the dense bit array located at data ，采用 size bits. The byte array at data must be at least 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()

PySide2.QtCore.QBitArray. isEmpty ( ) ¶

返回类型

bool

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

另请参阅

size()

PySide2.QtCore.QBitArray. isNull ( ) ¶

返回类型

bool

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()

PySide2.QtCore.QBitArray. __ne__ ( other ) ¶

参数

other – QBitArray

返回类型

bool

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

另请参阅

operator==()

PySide2.QtCore.QBitArray. __and__ ( arg__2 ) ¶

参数

arg__2 – QBitArray

返回类型

QBitArray

PySide2.QtCore.QBitArray. __and__ ( arg__2 ) ¶

参数

arg__2 – QBitArray

返回类型

QBitArray

PySide2.QtCore.QBitArray. __iand__ ( arg__1 ) ¶

参数

arg__1 – QBitArray

返回类型

QBitArray

PySide2.QtCore.QBitArray. __eq__ ( other ) ¶

参数

other – QBitArray

返回类型

bool

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

另请参阅

operator!=()

PySide2.QtCore.QBitArray.operator[](i)

参数

i – int

返回类型

bool

这是重载函数。

PySide2.QtCore.QBitArray.operator[](i)

参数

i – uint

返回类型

bool

这是重载函数。

PySide2.QtCore.QBitArray. __xor__ ( arg__2 ) ¶

参数

arg__2 – QBitArray

返回类型

QBitArray

PySide2.QtCore.QBitArray. __ixor__ ( arg__1 ) ¶

参数

arg__1 – QBitArray

返回类型

QBitArray

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：

a = QBitArray(3)
b = QBitArray(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 ]
											

另请参阅

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

PySide2.QtCore.QBitArray. __or__ ( arg__2 ) ¶

参数

arg__2 – QBitArray

返回类型

QBitArray

PySide2.QtCore.QBitArray. __ior__ ( arg__1 ) ¶

参数

arg__1 – QBitArray

返回类型

QBitArray

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：

a = QBitArray(3)
b = QBitArray(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 ]
											

另请参阅

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

PySide2.QtCore.QBitArray.operator~()

返回类型

QBitArray

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

范例：

a = QBitArray(3)
b = QBitArray()
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|() operator^()

PySide2.QtCore.QBitArray. resize ( size ) ¶

参数

size – int

Resizes the bit array to size bits.

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()

PySide2.QtCore.QBitArray. setBit ( i ) ¶

参数

i – int

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() toggleBit()

PySide2.QtCore.QBitArray. setBit ( i , val ) ¶

参数

• i – int

• val – bool

这是重载函数。

Sets the bit at index position i to value .

PySide2.QtCore.QBitArray. size ( ) ¶

返回类型

int

Returns the number of bits stored in the bit array.

另请参阅

resize()

PySide2.QtCore.QBitArray. swap ( other ) ¶

参数

other – QBitArray

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

PySide2.QtCore.QBitArray. testBit ( i ) ¶

参数

i – int

返回类型

bool

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() ).

另请参阅

setBit() clearBit()

PySide2.QtCore.QBitArray. toggleBit ( i ) ¶

参数

i – int

返回类型

bool

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() ).

另请参阅

setBit() clearBit()

PySide2.QtCore.QBitArray. truncate ( pos ) ¶

参数

pos – int

Truncates the bit array at index position pos .

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

另请参阅

resize()