python内置函数2-bytearra

2023-01-31 02:01:31 python 函数

Help on class bytearray in module __builtin__:

class bytearray(object)

| bytearray(iterable_of_ints) -> bytearray.

| bytearray(string, encoding[, errors]) -> bytearray.

| bytearray(bytes_or_bytearray) -> mutable copy of bytes_or_bytearray.

| bytearray(memory_view) -> bytearray.

| Construct an mutable bytearray object from:

| - an iterable yielding integers in range(256)

| - a text string encoded using the specified encoding

| - a bytes or a bytearray object

| - any object implementing the buffer api.

| bytearray(int) -> bytearray.

| Construct a zero-initialized bytearray of the given length.

| Methods defined here:

| __add__(...)

| x.__add__(y) <==> x+y

| __alloc__(...)

| B.__alloc__() -> int

| Returns the number of bytes actually allocated.

| __contains__(...)

| x.__contains__(y) <==> y in x

| __delitem__(...)

| x.__delitem__(y) <==> del x[y]

| __eq__(...)

| x.__eq__(y) <==> x==y

| __ge__(...)

| x.__ge__(y) <==> x>=y

| __getattribute__(...)

| x.__getattribute__('name') <==> x.name

| __getitem__(...)

| x.__getitem__(y) <==> x[y]

| __gt__(...)

| x.__gt__(y) <==> x>y

| __iadd__(...)

| x.__iadd__(y) <==> x+=y

| __imul__(...)

| x.__imul__(y) <==> x*=y

| __init__(...)

| x.__init__(...) initializes x; see help(type(x)) for signature

| __iter__(...)

| x.__iter__() <==> iter(x)

| __le__(...)

| x.__le__(y) <==> x<=y

| __len__(...)

| x.__len__() <==> len(x)

| __lt__(...)

| x.__lt__(y) <==> x<y

| __mul__(...)

| x.__mul__(n) <==> x*n

| __ne__(...)

| x.__ne__(y) <==> x!=y

| __reduce__(...)

| Return state infORMation for pickling.

| __repr__(...)

| x.__repr__() <==> repr(x)

| __rmul__(...)

| x.__rmul__(n) <==> n*x

| __setitem__(...)

| x.__setitem__(i, y) <==> x[i]=y

| __sizeof__(...)

| B.__sizeof__() -> int

| Returns the size of B in memory, in bytes

| __str__(...)

| x.__str__() <==> str(x)

| append(...)

| B.append(int) -> None

| Append a single item to the end of B.

| capitalize(...)

| B.capitalize() -> copy of B

| Return a copy of B with only its first character capitalized (ASCII)

| and the rest lower-cased.

| center(...)

| B.center(width[, fillchar]) -> copy of B

| Return B centered in a string of length width. Padding is

| done using the specified fill character (default is a space).

| count(...)

| B.count(sub [,start [,end]]) -> int

| Return the number of non-overlapping occurrences of subsection sub in

| bytes B[start:end]. Optional arguments start and end are interpreted

| as in slice notation.

| decode(...)

| B.decode([encoding[, errors]]) -> unicode object.

| Decodes B using the codec reGIStered for encoding. encoding defaults

| to the default encoding. errors may be given to set a different error

| handling scheme. Default is 'strict' meaning that encoding errors raise

| a UnicodeDecodeError. Other possible values are 'ignore' and 'replace'

| as well as any other name registered with codecs.register_error that is

| able to handle UnicodeDecodeErrors.

| endswith(...)

| B.endswith(suffix [,start [,end]]) -> bool

| Return True if B ends with the specified suffix, False otherwise.

| With optional start, test B beginning at that position.

| With optional end, stop comparing B at that position.

| suffix can also be a tuple of strings to try.

| expandtabs(...)

| B.expandtabs([tabsize]) -> copy of B

| Return a copy of B where all tab characters are expanded using spaces.

| If tabsize is not given, a tab size of 8 characters is assumed.

| extend(...)

| B.extend(iterable int) -> None

| Append all the elements from the iterator or sequence to the

| end of B.

| find(...)

| B.find(sub [,start [,end]]) -> int

| Return the lowest index in B where subsection sub is found,

| such that sub is contained within B[start,end]. Optional

| arguments start and end are interpreted as in slice notation.

| Return -1 on failure.

| fromhex(...)

| bytearray.fromhex(string) -> bytearray

| Create a bytearray object from a string of hexadecimal numbers.

| Spaces between two numbers are accepted.

| Example: bytearray.fromhex('B9 01EF') -> bytearray(b'\xb9\x01\xef').

| index(...)

| B.index(sub [,start [,end]]) -> int

| Like B.find() but raise ValueError when the subsection is not found.

| insert(...)

| B.insert(index, int) -> None

| Insert a single item into the bytearray before the given index.

| isalnum(...)

| B.isalnum() -> bool

| Return True if all characters in B are alphanumeric

| and there is at least one character in B, False otherwise.

| isalpha(...)

| B.isalpha() -> bool

| Return True if all characters in B are alphabetic

| and there is at least one character in B, False otherwise.

| isdigit(...)

| B.isdigit() -> bool

| Return True if all characters in B are digits

| and there is at least one character in B, False otherwise.

| islower(...)

| B.islower() -> bool

| Return True if all cased characters in B are lowercase and there is

| at least one cased character in B, False otherwise.

| isspace(...)

| B.isspace() -> bool

| Return True if all characters in B are whitespace

| and there is at least one character in B, False otherwise.

| istitle(...)

| B.istitle() -> bool

| Return True if B is a titlecased string and there is at least one

| character in B, i.e. uppercase characters may only follow uncased

| characters and lowercase characters only cased ones. Return False

| otherwise.

| isupper(...)

| B.isupper() -> bool

| Return True if all cased characters in B are uppercase and there is

| at least one cased character in B, False otherwise.

| join(...)

| B.join(iterable_of_bytes) -> bytes

| Concatenates any number of bytearray objects, with B in between each pair.

| ljust(...)

| B.ljust(width[, fillchar]) -> copy of B

| Return B left justified in a string of length width. Padding is

| done using the specified fill character (default is a space).

| lower(...)

| B.lower() -> copy of B

| Return a copy of B with all ASCII characters converted to lowercase.

| lstrip(...)

| B.lstrip([bytes]) -> bytearray

| Strip leading bytes contained in the argument.

| If the argument is omitted, strip leading ASCII whitespace.

| partition(...)

| B.partition(sep) -> (head, sep, tail)

| Searches for the separator sep in B, and returns the part before it,

| the separator itself, and the part after it. If the separator is not

| found, returns B and two empty bytearray objects.

| pop(...)

| B.pop([index]) -> int

| Remove and return a single item from B. If no index

| argument is given, will pop the last value.

| remove(...)

| B.remove(int) -> None

| Remove the first occurance of a value in B.

| replace(...)

| B.replace(old, new[, count]) -> bytes

| Return a copy of B with all occurrences of subsection

| old replaced by new. If the optional argument count is

| given, only the first count occurrences are replaced.

| reverse(...)

| B.reverse() -> None

| Reverse the order of the values in B in place.

| rfind(...)

| B.rfind(sub [,start [,end]]) -> int

| Return the highest index in B where subsection sub is found,

| such that sub is contained within B[start,end]. Optional

| arguments start and end are interpreted as in slice notation.

| Return -1 on failure.

| rindex(...)

| B.rindex(sub [,start [,end]]) -> int

| Like B.rfind() but raise ValueError when the subsection is not found.

| rjust(...)

| B.rjust(width[, fillchar]) -> copy of B

| Return B right justified in a string of length width. Padding is

| done using the specified fill character (default is a space)

| rpartition(...)

| B.rpartition(sep) -> (head, sep, tail)

| Searches for the separator sep in B, starting at the end of B,

| and returns the part before it, the separator itself, and the

| part after it. If the separator is not found, returns two empty

| bytearray objects and B.

| rsplit(...)

| B.rsplit(sep[, maxsplit]) -> list of bytearray

| Return a list of the sections in B, using sep as the delimiter,

| starting at the end of B and working to the front.

| If sep is not given, B is split on ASCII whitespace characters

| (space, tab, return, newline, formfeed, vertical tab).

| If maxsplit is given, at most maxsplit splits are done.

| rstrip(...)

| B.rstrip([bytes]) -> bytearray

| Strip trailing bytes contained in the argument.

| If the argument is omitted, strip trailing ASCII whitespace.

| split(...)

| B.split([sep[, maxsplit]]) -> list of bytearray

| Return a list of the sections in B, using sep as the delimiter.

| If sep is not given, B is split on ASCII whitespace characters

| (space, tab, return, newline, formfeed, vertical tab).

| If maxsplit is given, at most maxsplit splits are done.

| splitlines(...)

| B.splitlines([keepends]) -> list of lines

| Return a list of the lines in B, breaking at line boundaries.

| Line breaks are not included in the resulting list unless keepends

| is given and true.

| startswith(...)

| B.startswith(prefix [,start [,end]]) -> bool

| Return True if B starts with the specified prefix, False otherwise.

| With optional start, test B beginning at that position.

| With optional end, stop comparing B at that position.

| prefix can also be a tuple of strings to try.

| strip(...)

| B.strip([bytes]) -> bytearray

| Strip leading and trailing bytes contained in the argument.

| If the argument is omitted, strip ASCII whitespace.

| swapcase(...)

| B.swapcase() -> copy of B

| Return a copy of B with uppercase ASCII characters converted

| to lowercase ASCII and vice versa.

| title(...)

| B.title() -> copy of B

| Return a titlecased version of B, i.e. ASCII Words start with uppercase

| characters, all remaining cased characters have lowercase.

| translate(...)

| B.translate(table[, deletechars]) -> bytearray

| Return a copy of B, where all characters occurring in the

| optional argument deletechars are removed, and the remaining

| characters have been mapped through the given translation

| table, which must be a bytes object of length 256.

| upper(...)

| B.upper() -> copy of B

| Return a copy of B with all ASCII characters converted to uppercase.

| zfill(...)

| B.zfill(width) -> copy of B

| Pad a numeric string B with zeros on the left, to fill a field

| of the specified width. B is never truncated.

| ----------------------------------------------------------------------

| Data and other attributes defined here:

| __new__ = <built-in method __new__ of type object>

| T.__new__(S, ...) -> a new object with type S, a subtype of T

class bytearray([source[, encoding[, errors]]])

Return a new array of bytes. The bytearray class is a mutable sequence of integers in the range 0 <= x < 256. It has most of the usual methods of mutable sequences, described in Mutable Sequence Types, as well as most methods that the str type has, see String Methods.

The optional source parameter can be used to initialize the array in a few different ways:

If it is unicode, you must also give the encoding (and optionally, errors) parameters; bytearray() then converts the unicode to bytes using unicode.encode().

If it is an integer, the array will have that size and will be initialized with null bytes.

If it is an object conforming to the buffer interface, a read-only buffer of the object will be used to initialize the bytes array.

If it is an iterable, it must be an iterable of integers in the range 0 <= x < 256, which are used as the initial contents of the array.

Without an argument, an array of size 0 is created.

中文说明：

bytearray([source [, encoding [, errors]]])返回一个byte数组。Bytearray类型是一个可变的序列，并且序列中的元素的取值范围为 [0 ,255]。

参数source:

如果source为整数，则返回一个长度为source的初始化数组；

如果source为字符串，则按照指定的encoding将字符串转换为字节序列；

如果source为可迭代类型，则元素必须为[0 ,255]中的整数；

如果source为与buffer接口一致的对象，则此对象也可以被用于初始化bytearray.。

>>> a=bytearray(3)

>>> a

bytearray(b'\x00\x00\x00')

>>> a[0]

>>> a[1]

>>> a[2]

>>> b=bytearray('abc')

>>> b

bytearray(b'abc')

>>> b[0]

>>> b[1]

>>> b[2]

>>> c=bytearray([1,2,3])

>>> c

bytearray(b'\x01\x02\x03')

>>> c[0]

>>> c[1]

>>> c[2]

>>> d=bytearray(buffer('abc'))

>>> d

bytearray(b'abc')

>>> d[0]

>>> d[1]

>>> d[2]

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