Python基本数据类型——str

Posted 2020-08-19

字符串常用操作

• 移除空白
• 分割
• 长度
• 索引
• 切片
  

  class str(basestring):
      """
      str(object=‘‘) -> string
      
      Return a nice string representation of the object.
      If the argument is a string, the return value is the same object.
      """
      def capitalize(self):  
          """ 首字母变大写 """
          """
          S.capitalize() -> string
          
          Return a copy of the string S with only its first character
          capitalized.
          """
          return ""
  
      def center(self, width, fillchar=None):  
          """ 内容居中，width：总长度；fillchar：空白处填充内容，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 ""
  
      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
  
      def decode(self, encoding=None, errors=None):  
          """ 解码 """
          """
          S.decode([encoding[,errors]]) -> object
          
          Decodes S 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.
          """
          return object()
  
      def encode(self, encoding=None, errors=None):  
          """ 编码，针对unicode """
          """
          S.encode([encoding[,errors]]) -> object
          
          Encodes S 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 UnicodeEncodeError. Other possible values are ‘ignore‘, ‘replace‘ and
          ‘xmlcharrefreplace‘ as well as any other name registered with
          codecs.register_error that is able to handle UnicodeEncodeErrors.
          """
          return object()
  
      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
  
      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 ""
  
      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
  
      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
  
      def index(self, sub, start=None, end=None):  
          """ 子序列位置，如果没找到，报错 """
          S.index(sub [,start [,end]]) -> int
          
          Like S.find() but raise ValueError when the substring is not found.
          """
          return 0
  
      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 isupper(self):  
          """
          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.
          """
          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 ""
  
      def ljust(self, width, fillchar=None):  
          """ 内容左对齐，右侧填充 """
          """
          S.ljust(width[, fillchar]) -> string
          
          Return S left-justified in a string of length width. Padding is
          done using the specified fill character (default is a space).
          """
          return ""
  
      def lower(self):  
          """ 变小写 """
          """
          S.lower() -> string
          
          Return a copy of the string S converted to lowercase.
          """
          return ""
  
      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 ""
  
      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 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 ""
  
      def rfind(self, sub, start=None, end=None):  
          """
          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.
          """
          return 0
  
      def rindex(self, sub, start=None, end=None):  
          """
          S.rindex(sub [,start [,end]]) -> int
          
          Like S.rfind() but raise ValueError when the substring is not found.
          """
          return 0
  
      def rjust(self, width, fillchar=None):  
          """
          S.rjust(width[, fillchar]) -> string
          
          Return S right-justified in a string of length width. Padding is
          done using the specified fill character (default is a space)
          """
          return ""
  
      def rpartition(self, sep):  
          """
          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.
          """
          pass
  
      def rsplit(self, sep=None, maxsplit=None):  
          """
          S.rsplit([sep [,maxsplit]]) -> list of strings
          
          Return a list of the words in the string 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 or is None, any whitespace string
          is a separator.
          """
          return []
  
      def rstrip(self, chars=None):  
          """
          S.rstrip([chars]) -> string or unicode
          
          Return a copy of the string S with trailing 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 ""
  
      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 splitlines(self, keepends=False):  
          """ 根据换行分割 """
          """
          S.splitlines(keepends=False) -> 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.
          """
          return []
  
      def startswith(self, prefix, start=None, end=None):  
          """ 是否起始 """
          """
          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.
          """
          return False
  
      def strip(self, chars=None):  
          """ 移除两段空白 """
          """
          S.strip([chars]) -> string or unicode
          
          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.
          If chars is unicode, S will be converted to unicode before stripping
          """
          return ""
  
      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 title(self):  
          """
          S.title() -> string
          
          Return a titlecased version of S, i.e. words start with uppercase
          characters, all remaining cased characters have lowercase.
          """
          return ""
  
      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‘)
          """
  
          """
          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 upper(self):  
          """
          S.upper() -> string
          
          Return a copy of the string S converted to uppercase.
          """
          return ""
  
      def zfill(self, width):  
          """方法返回指定长度的字符串，原字符串右对齐，前面填充0。"""
          """
          S.zfill(width) -> string
          
          Pad a numeric string S with zeros on the left, to fill a field
          of the specified width.  The string S is never truncated.
          """
          return ""
  
      def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown
          pass
  
      def _formatter_parser(self, *args, **kwargs): # real signature unknown
          pass
  
      def __add__(self, y):  
          """ x.__add__(y) <==> x+y """
          pass
  
      def __contains__(self, y):  
          """ x.__contains__(y) <==> y in x """
          pass
  
      def __eq__(self, y):  
          """ x.__eq__(y) <==> x==y """
          pass
  
      def __format__(self, format_spec):  
          """
          S.__format__(format_spec) -> string
          
          Return a formatted version of S as described by format_spec.
          """
          return ""
  
      def __getattribute__(self, name):  
          """ x.__getattribute__(‘name‘) <==> x.name """
          pass
  
      def __getitem__(self, y):  
          """ x.__getitem__(y) <==> x[y] """
          pass
  
      def __getnewargs__(self, *args, **kwargs): # real signature unknown
          pass
  
      def __getslice__(self, i, j):  
          """
          x.__getslice__(i, j) <==> x[i:j]
                     
                     Use of negative indices is not supported.
          """
          pass
  
      def __ge__(self, y):  
          """ x.__ge__(y) <==> x>=y """
          pass
  
      def __gt__(self, y):  
          """ x.__gt__(y) <==> x>y """
          pass
  
      def __hash__(self):  
          """ x.__hash__() <==> hash(x) """
          pass
  
      def __init__(self, string=‘‘): # known special case of str.__init__
          """
          str(object=‘‘) -> string
          
          Return a nice string representation of the object.
          If the argument is a string, the return value is the same object.
          # (copied from class doc)
          """
          pass
  
      def __len__(self):  
          """ x.__len__() <==> len(x) """
          pass
  
      def __le__(self, y):  
          """ x.__le__(y) <==> x<=y """
          pass
  
      def __lt__(self, y):  
          """ x.__lt__(y) <==> x<y """
          pass
  
      def __mod__(self, y):  
          """ x.__mod__(y) <==> x%y """
          pass
  
      def __mul__(self, n):  
          """ x.__mul__(n) <==> x*n """
          pass
  
      @staticmethod # known case of __new__
      def __new__(S, *more):  
          """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
          pass
  
      def __ne__(self, y):  
          """ x.__ne__(y) <==> x!=y """
          pass
  
      def __repr__(self):  
          """ x.__repr__() <==> repr(x) """
          pass
  
      def __rmod__(self, y):  
          """ x.__rmod__(y) <==> y%x """
          pass
  
      def __rmul__(self, n):  
          """ x.__rmul__(n) <==> n*x """
          pass
  
      def __sizeof__(self):  
          """ S.__sizeof__() -> size of S in memory, in bytes """
          pass
  
      def __str__(self):  
          """ x.__str__() <==> str(x) """
          pass
  
  str

  str

 EX:

移除空格——strip、rstrip、lstrip

#字符串去除空格

#去除左右空格
s1 = "   hello，world!   "
result = s1.strip()
print(result)

#去除左空格
s1 = "   hello，world!   "
result = s1.lstrip()
print(result)

#去除右空格
s1 = "   hello, world!   "
result = s1.rstrip()
print(result)

strip

 分割&切割——partition、rpartition\\split、rsplit、splitlines

#字符串操作——分割、切割

#分割（前中后3部分），返回结果类型为元组
s1 = "   hello, world!   "
#以‘l’分割字符
print(s1.partition(‘l‘))
#rpartition分割（前中后3部分），返回结果类型为元组
s1 = "   hello, world!   "
#以‘l’分割字符
print(s1.rpartition(‘l‘))

----------------------------------------------------

# split字符串的切割，return结果是列表
s1 = "   hello, world!   "
result = s1.split(sep=‘o‘,maxsplit=2)
print(result)
#[‘   hell‘, ‘, w‘, ‘rld!   ‘]

# splitlines字符串以换行符切割，return结果是列表
s1 = "   hello, \\nworld!   "
result = s1.splitlines(keepends=False)
print(result)
#[‘   hello, ‘, ‘world!   ‘]

split