def capitalize(self): """ 首字母变大写，其余字母一律变小写 """ """ S.capitalize() -> string Return a copy of the string S with only its first character capitalized. """ return "" for example s = 'abcd' s.capitalize()----->'Abcd'
s = 'abCsd' s.lower() #全部变小写字母 -> abcsd s.casefold() #全部变小写字母，相较于lower更强大，能转换多种语言的大小写 -> abcsd s.upper() #全部变大写字母 -> ABCSD s.capitalize() #一个字符串中只有第一个字母大写，其余一律小写 -> Abcsd
def center(self, width, fillchar=None): """ 内容居中，width：总长度；fillchar：空白处填充内容,并且只能填一个字符，默认无 """ """ S.center(width[, fillchar]) -> string Return S centered in a string of length width. Padding is done using the specified fill character (default is a space) """ return "" for example s = 'adaf' s.center(20,'*') -> ********adaf******** 总共20位的空间，用‘*’取代空白处
扩展： s.ljust(20,'*') -> adaf****************
s.rjust(20,'*') -> ****************adaf
def count(self, sub, start=None, end=None): """ 子序列个数 """ """ 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. """ return 0 for example a = 'aaadd' a.count('a') -> 3 a.count('d',3) -> 2 a.count('d',3,4) -> 1 由上式可知，取值区间左闭右开
def expandtabs(self, tabsize=None): """ 将tab转换成空格，默认一个tab转换成8个空格 """ """ S.expandtabs([tabsize]) -> string 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. """ return "" for example a = 'aaa dddd dd' a.expandtabs() -> aaa dddd dd 可见以8位为一个单位，不足的用空格替换，这对于表格对齐有用
def endswith(self, suffix, start=None, end=None): """ 是否以 xxx 结束 """ """ 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. """ return False for example a = '012345' a.endswith('5') -> True a.endswith('5',3) -> True a.endswith('45') -> True a.endswith('345') -> True a.endswith('2345') -> False
同理还有startswith（）
def find(self, sub, start=None, end=None): """ 寻找子序列位置，如果没找到，返回 -1 """ """ 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. """ return 0 for example a = 'abcd' a.find('c') -> 2 a.find('c',1,2) -> -1 找值区间遵循左闭右开
def format(*args, **kwargs): # known special case of str.format """ 字符串格式化，动态参数，将函数式编程时细说 """ """ S.format(*args, **kwargs) -> string Return a formatted version of S, using substitutions from args and kwargs. The substitutions are identified by braces ('{' and '}'). """ pass for example a = 'i am {name}' print(a) -> i am name print(a.format(name = 'pig')) -> i am pig 将字符串的占位符替换为输入的值
def isalnum(self): """ 是否是字母和数字 """ """ S.isalnum() -> bool Return True if all characters in S are alphanumeric and there is at least one character in S, False otherwise. """ return False def isalpha(self): """ 是否是字母 """ """ S.isalpha() -> bool Return True if all characters in S are alphabetic and there is at least one character in S, False otherwise. """ return False def isdigit(self): """ 是否是数字 """ """ S.isdigit() -> bool Return True if all characters in S are digits and there is at least one character in S, False otherwise. """ return False def islower(self): """ 是否小写 """ """ 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. """ return False def isspace(self): """ S.isspace() -> bool Return True if all characters in S are whitespace and there is at least one character in S, False otherwise. """ return False def istitle(self): """ S.istitle() -> bool Return True if S is a titlecased string and there is at least one character in S, i.e. uppercase characters may only follow uncased characters and lowercase characters only cased ones. Return False otherwise. """ return False
def join(self, iterable): """ 连接 """ """ S.join(iterable) -> string Return a string which is the concatenation of the strings in the iterable. The separator between elements is S. """ return "" for example v = '_'join('adc') -> a_d_c
def lstrip(self, chars=None): """ 移除左侧空白 """ """ S.lstrip([chars]) -> string or unicode Return a copy of the string S with leading whitespace removed. If chars is given and not None, remove characters in chars instead. If chars is unicode, S will be converted to unicode before stripping """ return "" 同类的有 rstrip() strip() 传入字符可以移除指定字符
def translate(self, table, deletechars=None): """ 转换，需要先做一个对应表，最后一个表示删除字符集合 intab = "aeiou" outtab = "12345" trantab = maketrans(intab, outtab) str = "this is string example....wow!!!" print str.translate(trantab, 'xm') -> m1k2tr1ns """ """ S.translate(table [,deletechars]) -> string Return a copy of the string S, 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 string of length 256 or None. If the table argument is None, no translation is applied and the operation simply removes the characters in deletechars. """ return ""
def split(self, sep=None, maxsplit=None): """ 分割， maxsplit最多分割几次 """ """ S.split([sep [,maxsplit]]) -> list of strings Return a list of the words in the string 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. """ return []
def partition(self, sep): """ 分割，前，中，后三部分 """ """ 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. """ pass
def swapcase(self): """ 大写变小写，小写变大写 """ """ S.swapcase() -> string Return a copy of the string S with uppercase characters converted to lowercase and vice versa. """ return ""
def replace(self, old, new, count=None): """ 替换 """ """ S.replace(old, new[, count]) -> string Return a copy of string S with all occurrences of substring old replaced by new. If the optional argument count is given, only the first count occurrences are replaced. """ return ""
注意：字符串的修改，拼接，不会再原字符串中操作，而是在新的内存里生成