8、'bytes', 字符串转换成字节流。第一个传入参数是要转换的字符串，第二个参数按什么编码转换为字节。
class bytes(object) | bytes(iterable_of_ints) -> bytes
# bytes([1, 2, 3, 4]) bytes must be in range(0, 256) | bytes(string, encoding[, errors]) -> bytes
# bytes('你妈嗨', encoding='utf-8') | bytes(bytes_or_buffer) -> immutable copy of bytes_or_buffer
# | bytes(int) -> bytes object of size given by the parameter initialized with null bytes | bytes() -> empty bytes object | | Construct an immutable array of bytes from: | - an iterable yielding integers in range(256) | - a text string encoded using the specified encoding | - any object implementing the buffer API. | - an integer | | Methods defined here: | | __add__(self, value, /) | Return self+value. | | __contains__(self, key, /) | Return key in self. | | __eq__(self, value, /) | Return self==value. | | __ge__(self, value, /) | Return self>=value. | | __getattribute__(self, name, /) | Return getattr(self, name). | | __getitem__(self, key, /) | Return self[key]. | | __getnewargs__(...) | | __gt__(self, value, /) | Return self>value. | | __hash__(self, /) | Return hash(self). | | __iter__(self, /) | Implement iter(self). | | __le__(self, value, /) | Return self<=value. | | __len__(self, /) | Return len(self). | | __lt__(self, value, /) | Return self<value. | | __mod__(self, value, /) | Return self%value. | | __mul__(self, value, /) | Return self*value.n | | __ne__(self, value, /) | Return self!=value. | | __new__(*args, **kwargs) from builtins.type | Create and return a new object. See help(type) for accurate signature. | | __repr__(self, /) | Return repr(self). | | __rmod__(self, value, /) | Return value%self. | | __rmul__(self, value, /) | Return self*value. | | __str__(self, /) | Return str(self). | | 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(self, /, encoding='utf-8', errors='strict') | Decode the bytes using the codec registered for encoding. | | encoding | The encoding with which to decode the bytes. | errors | The error handling scheme to use for the handling of decoding errors. | The default is 'strict' meaning that decoding errors raise a | UnicodeDecodeError. Other possible values are 'ignore' and 'replace' | as well as any other name registered with codecs.register_error that | can 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 bytes to try. | | expandtabs(...) | B.expandtabs(tabsize=8) -> 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. | | 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(string, /) from builtins.type | Create a bytes object from a string of hexadecimal numbers. | | Spaces between two numbers are accepted. | Example: bytes.fromhex('B9 01EF') -> b'\xb9\x01\xef'. | | hex(...) | B.hex() -> string | | Create a string of hexadecimal numbers from a bytes object. | Example: b'xb9x01xef'.hex() -> 'b901ef'. | | index(...) | B.index(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. | | Raises ValueError when the subsection is not found. | | 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(self, iterable_of_bytes, /) | Concatenate any number of bytes objects. | | The bytes whose method is called is inserted in between each pair. | | The result is returned as a new bytes object. | | Example: b'.'.join([b'ab', b'pq', b'rs']) -> b'ab.pq.rs'. | | 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(self, bytes=None, /) | Strip leading bytes contained in the argument. | | If the argument is omitted or None, strip leading ASCII whitespace. | | partition(self, sep, /) | Partition the bytes into three parts using the given separator. | | This will search for the separator sep in the bytes. If the separator is found, | returns a 3-tuple containing the part before the separator, the separator | itself, and the part after it. | | If the separator is not found, returns a 3-tuple containing the original bytes | object and two empty bytes objects. | | replace(self, old, new, count=-1, /) | Return a copy with all occurrences of substring old replaced by new. | | count | Maximum number of occurrences to replace. | -1 (the default value) means replace all occurrences. | | If the optional argument count is given, only the first count occurrences are | replaced. | | 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 | | 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. | | 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(self, sep, /) | Partition the bytes into three parts using the given separator. | | This will search for the separator sep in the bytes, starting and the end. If | the separator is found, returns a 3-tuple containing the part before the | separator, the separator itself, and the part after it. | | If the separator is not found, returns a 3-tuple containing two empty bytes | objects and the original bytes object. | | rsplit(self, /, sep=None, maxsplit=-1) | Return a list of the sections in the bytes, using sep as the delimiter. | | sep | The delimiter according which to split the bytes. | None (the default value) means split on ASCII whitespace characters | (space, tab, return, newline, formfeed, vertical tab). | maxsplit | Maximum number of splits to do. | -1 (the default value) means no limit. | | Splitting is done starting at the end of the bytes and working to the front. | | rstrip(self, bytes=None, /) | Strip trailing bytes contained in the argument. | | If the argument is omitted or None, strip trailing ASCII whitespace. | | split(self, /, sep=None, maxsplit=-1) | Return a list of the sections in the bytes, using sep as the delimiter. | | sep | The delimiter according which to split the bytes. | None (the default value) means split on ASCII whitespace characters | (space, tab, return, newline, formfeed, vertical tab). | maxsplit | Maximum number of splits to do. | -1 (the default value) means no limit. | | splitlines(self, /, keepends=False) | Return a list of the lines in the bytes, 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 bytes to try. | | strip(self, bytes=None, /) | Strip leading and trailing bytes contained in the argument. | | If the argument is omitted or None, strip leading and trailing 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(self, table, /, delete=b'') | Return a copy with each character mapped by the given translation table. | | table | Translation table, which must be a bytes object of length 256. | | All characters occurring in the optional argument delete are removed. | The remaining characters are mapped through the given translation table. | | 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. | | ---------------------------------------------------------------------- | Static methods defined here: | | maketrans(frm, to, /) | Return a translation table useable for the bytes or bytearray translate method. | | The returned table will be one where each byte in frm is mapped to the byte at | the same position in to. | | The bytes objects frm and to must be of the same length.