数据类型的内置函数
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字符串内建函数(str)
capitalize()案例
#capitalize 首字母大写 s = ‘this is dog‘ print(s) print(id(s)) New_s = s.capitalize() print(New_s) print(id(New_s))
字符串的相关函数
Help on class str in module builtins: class str(object) | str(object=‘‘) -> str | str(bytes_or_buffer[, encoding[, errors]]) -> str | | Create a new string object from the given object. If encoding or | errors is specified, then the object must expose a data buffer | that will be decoded using the given encoding and error handler. | Otherwise, returns the result of object.__str__() (if defined) | or repr(object). | encoding defaults to sys.getdefaultencoding(). | errors defaults to ‘strict‘. | | Methods defined here: | | __add__(self, value, /) | Return self+value. | | __contains__(self, key, /) | Return key in self. | | __eq__(self, value, /) | Return self==value. | | __format__(...) | S.__format__(format_spec) -> str | | Return a formatted version of S as described by format_spec. | | __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. | | __sizeof__(...) | S.__sizeof__() -> size of S in memory, in bytes | | __str__(self, /) | Return str(self). | | capitalize(...) | S.capitalize() -> str | | Return a capitalized version of S, i.e. make the first character | have upper case and the rest lower case. | | casefold(...) | S.casefold() -> str | | Return a version of S suitable for caseless comparisons. | | center(...) | S.center(width[, fillchar]) -> str | | Return S centered in a string of length width. Padding is | done using the specified fill character (default is a space) | | count(...) | S.count(sub[, start[, end]]) -> int | | Return the number of non-overlapping occurrences of substring sub in | string S[start:end]. Optional arguments start and end are | interpreted as in slice notation. | | encode(...) | S.encode(encoding=‘utf-8‘, errors=‘strict‘) -> bytes | | Encode S using the codec registered for encoding. Default encoding | is ‘utf-8‘. errors may be given to set a different error | handling scheme. Default is ‘strict‘ meaning that encoding errors raise | a UnicodeEncodeError. Other possible values are ‘ignore‘, ‘replace‘ and | ‘xmlcharrefreplace‘ as well as any other name registered with | codecs.register_error that can handle UnicodeEncodeErrors. | | endswith(...) | S.endswith(suffix[, start[, end]]) -> bool | | Return True if S ends with the specified suffix, False otherwise. | With optional start, test S beginning at that position. | With optional end, stop comparing S at that position. | suffix can also be a tuple of strings to try. | | expandtabs(...) | S.expandtabs(tabsize=8) -> str | | Return a copy of S where all tab characters are expanded using spaces. | If tabsize is not given, a tab size of 8 characters is assumed. | | find(...) | S.find(sub[, start[, end]]) -> int | | Return the lowest index in S where substring sub is found, | such that sub is contained within S[start:end]. Optional | arguments start and end are interpreted as in slice notation. | | Return -1 on failure. | | format(...) | S.format(*args, **kwargs) -> str | | Return a formatted version of S, using substitutions from args and kwargs. | The substitutions are identified by braces (‘{‘ and ‘}‘). | | format_map(...) | S.format_map(mapping) -> str | | Return a formatted version of S, using substitutions from mapping. | The substitutions are identified by braces (‘{‘ and ‘}‘). | | index(...) | S.index(sub[, start[, end]]) -> int | | Return the lowest index in S where substring sub is found, | such that sub is contained within S[start:end]. Optional | arguments start and end are interpreted as in slice notation. | | Raises ValueError when the substring is not found. | | isalnum(...) | S.isalnum() -> bool | | Return True if all characters in S are alphanumeric | and there is at least one character in S, False otherwise. | | isalpha(...) | S.isalpha() -> bool | | Return True if all characters in S are alphabetic | and there is at least one character in S, False otherwise. | | isdecimal(...) | S.isdecimal() -> bool | | Return True if there are only decimal characters in S, | False otherwise. | | isdigit(...) | S.isdigit() -> bool | | Return True if all characters in S are digits | and there is at least one character in S, False otherwise. | | isidentifier(...) | S.isidentifier() -> bool | | Return True if S is a valid identifier according | to the language definition. | | Use keyword.iskeyword() to test for reserved identifiers | such as "def" and "class". | | islower(...) | S.islower() -> bool | | Return True if all cased characters in S are lowercase and there is | at least one cased character in S, False otherwise. | | isnumeric(...) | S.isnumeric() -> bool | | Return True if there are only numeric characters in S, | False otherwise. | | isprintable(...) | S.isprintable() -> bool | | Return True if all characters in S are considered | printable in repr() or S is empty, False otherwise. | | isspace(...) | S.isspace() -> bool | | Return True if all characters in S are whitespace | and there is at least one character in S, False otherwise. | | istitle(...) | S.istitle() -> bool | | Return True if S is a titlecased string and there is at least one | character in S, i.e. upper- and titlecase characters may only | follow uncased characters and lowercase characters only cased ones. | Return False otherwise. | | isupper(...) | S.isupper() -> bool | | Return True if all cased characters in S are uppercase and there is | at least one cased character in S, False otherwise. | | join(...) | S.join(iterable) -> str | | Return a string which is the concatenation of the strings in the | iterable. The separator between elements is S. | | ljust(...) | S.ljust(width[, fillchar]) -> str | | Return S left-justified in a Unicode string of length width. Padding is | done using the specified fill character (default is a space). | | lower(...) | S.lower() -> str | | Return a copy of the string S converted to lowercase. | | lstrip(...) | S.lstrip([chars]) -> str | | Return a copy of the string S with leading whitespace removed. | If chars is given and not None, remove characters in chars instead. | | partition(...) | S.partition(sep) -> (head, sep, tail) | | Search for the separator sep in S, and return the part before it, | the separator itself, and the part after it. If the separator is not | found, return S and two empty strings. | | replace(...) | S.replace(old, new[, count]) -> str | | Return a copy of S with all occurrences of substring | old replaced by new. If the optional argument count is | given, only the first count occurrences are replaced. | | rfind(...) | S.rfind(sub[, start[, end]]) -> int | | Return the highest index in S where substring sub is found, | such that sub is contained within S[start:end]. Optional | arguments start and end are interpreted as in slice notation. | | Return -1 on failure. | | rindex(...) | S.rindex(sub[, start[, end]]) -> int | | Return the highest index in S where substring sub is found, | such that sub is contained within S[start:end]. Optional | arguments start and end are interpreted as in slice notation. | | Raises ValueError when the substring is not found. | | rjust(...) | S.rjust(width[, fillchar]) -> str | | Return S right-justified in a string of length width. Padding is | done using the specified fill character (default is a space). | | rpartition(...) | S.rpartition(sep) -> (head, sep, tail) | | Search for the separator sep in S, starting at the end of S, and return | the part before it, the separator itself, and the part after it. If the | separator is not found, return two empty strings and S. | | rsplit(...) | S.rsplit(sep=None, maxsplit=-1) -> list of strings | | Return a list of the words in S, using sep as the | delimiter string, starting at the end of the string and | working to the front. If maxsplit is given, at most maxsplit | splits are done. If sep is not specified, any whitespace string | is a separator. | | rstrip(...) | S.rstrip([chars]) -> str | | Return a copy of the string S with trailing whitespace removed. | If chars is given and not None, remove characters in chars instead. | | split(...) | S.split(sep=None, maxsplit=-1) -> list of strings | | Return a list of the words in S, using sep as the | delimiter string. If maxsplit is given, at most maxsplit | splits are done. If sep is not specified or is None, any | whitespace string is a separator and empty strings are | removed from the result. | | splitlines(...) | S.splitlines([keepends]) -> list of strings | | Return a list of the lines in S, breaking at line boundaries. | Line breaks are not included in the resulting list unless keepends | is given and true. | | startswith(...) | S.startswith(prefix[, start[, end]]) -> bool | | Return True if S starts with the specified prefix, False otherwise. | With optional start, test S beginning at that position. | With optional end, stop comparing S at that position. | prefix can also be a tuple of strings to try. | | strip(...) | S.strip([chars]) -> str | | Return a copy of the string S with leading and trailing | whitespace removed. | If chars is given and not None, remove characters in chars instead. | | swapcase(...) | S.swapcase() -> str | | Return a copy of S with uppercase characters converted to lowercase | and vice versa. | | title(...) | S.title() -> str | | Return a titlecased version of S, i.e. words start with title case | characters, all remaining cased characters have lower case. | | translate(...) | S.translate(table) -> str | | Return a copy of the string S in which each character has been mapped | through the given translation table. The table must implement | lookup/indexing via __getitem__, for instance a dictionary or list, | mapping Unicode ordinals to Unicode ordinals, strings, or None. If | this operation raises LookupError, the character is left untouched. | Characters mapped to None are deleted. | | upper(...) | S.upper() -> str | | Return a copy of S converted to uppercase. | | zfill(...) | S.zfill(width) -> str | | Pad a numeric string S with zeros on the left, to fill a field | of the specified width. The string S is never truncated. | | ---------------------------------------------------------------------- | Static methods defined here: | | maketrans(x, y=None, z=None, /) | Return a translation table usable for str.translate(). | | If there is only one argument, it must be a dictionary mapping Unicode | ordinals (integers) or characters to Unicode ordinals, strings or None. | Character keys will be then converted to ordinals. | If there are two arguments, they must be strings of equal length, and | in the resulting dictionary, each character in x will be mapped to the | character at the same position in y. If there is a third argument, it | must be a string, whose characters will be mapped to None in the result.
title()案例
# title 将每个单词的字母大写 s = ‘this is dog‘ print(s) print(id(s)) New_s = s.title() print(New_s) print(id(New_s))
upper案例
# upper 所有字母都是大 s = ‘this is dog‘ print(s.upper())
lower案例
# lower 将小写变为大写 s = ‘THIS IS DOG‘ print(s.lower())
swapcase案例
# swapcase 大小写互换 s = ‘this is dog,THIS IS DOG‘ print(s.swapcase())
len()
# len()计算字符串的长度，不是字符串的内建函数 s = ‘this is dog,THIS IS DOG‘ print(len(s))
find()，index()案例
# find 查找指定的字符串，找不到返回-1,找到返回索引值 # index查找指定字符串，找不到报ValueError错 s = ‘abcdefghigk‘ s1 = s.find(‘b‘) s2 = s.find(‘l‘) print(s1,s2) s3 = s.index(‘b‘) s4 = s.index(‘l‘) print(s3,s4)
count()案列
# count() 计算字符串出现的错误 s = ‘fsdhasidugfisdf‘ d = s.count(‘s‘) print(d)
startwith(),endwith()案例
# startwith()检测是否以指定字母开头，返回布尔值 # endwith()检测是否以指定字母结束 s = ‘fsdhasidugfisdf‘ print(s.startswith(‘f‘)) print(s.startswith(‘s‘)) print(‘--‘*20) print(s.endswith(‘f‘)) print(s.endswith(‘d‘))
isupper(),islower(),
# isupper() 检测所有字母是否大写字母 # islower()检测所有字母是否小写字母 s = ‘ffffsds‘ s1 = ‘FFFSDDS‘ print(s.isupper()) print(s1.isupper()) print("="*20) print(s.islower()) print(s1.islower())
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