Python数据类型

基本数据类型

 数字 整型 int
  -int
   将字符串转换为数字
    a = "123a"
    print(type(a),a)
    b = int(a)
    print(type(b),b)
    
    num = "0011"
    v = int(num,base = 16)##十六进制表示v
    print(v)
    
  -bit_length
   当前数字的二进制，至少用n位表示
   r = age.bit_length()
 
 字符串 str
 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'.
   """
  def capitalize(self, *args, **kwargs): # real signature unknown
   #返回首字母大写的字符串
   
   """
   Return a capitalized version of the string.
   
   More specifically, make the first character have upper case and the rest lower
   case.
   """
   pass

  def casefold(self, *args, **kwargs): # real signature unknown
   #所有字符大写转小写 类似lower()
   """ Return a version of the string suitable for caseless comparisons. """
   pass

  def center(self, *args, **kwargs): # real signature unknown
   test="vcc"
   v=test.center(20,'*')
   #设置宽度，并将内容居中，20代表总长度 剩余用*补足
   """
   Return a centered string of length width.
   
   Padding is done using the specified fill character (default is a space).
   """
   pass

  def count(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
   #去字符串中查找子序列出现的次数   
   """
   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 encode(self, *args, **kwargs): # real signature unknown
   """
   Encode the string using the codec registered for encoding.
   
     encoding
    The encoding in which to encode the string.
     errors
    The error handling scheme to use for encoding errors.
    The 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.
   """
   pass

  def endswith(self, suffix, start=None, end=None): # real signature unknown; restored from __doc__
   查看字符串是否以某个字符串结尾 返回True/False
   """
   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, *args, **kwargs): # real signature unknown
   #返回字符串中的 tab 符号('\t')转为空格后生成的新字符串 
    test = "vcc\t19\tman\t\nvcc\t19\tman\t\nvcc\t19\tman\t\nvcc\t19\tman\t\n"
    v=test.expandtabs(20)
    print(v)
    结果：
    vcc                 19                  man                
    vcc                 19                  man                
    vcc                 19                  man                
    vcc                 19                  man 
   """
   Return a copy where all tab characters are expanded using spaces.
   
   If tabsize is not given, a tab size of 8 characters is assumed.
   """
   pass

  def find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
   从开始往后找，找到第一个后，获取其位置
   例：test="asdfasdfasdf"
    v=test.find('as',6,11) ##>=6 <11 结果8
    print(v)
   """
   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(self, *args, **kwargs): # known special case of str.format
   #格式化，将一个字符串中的占位符替换为指定的值
    test='i am {0},age{1}'
    v = test.format("Vcc",10)
    print(v)
   """
   S.format(*args, **kwargs) -> str
   
   Return a formatted version of S, using substitutions from args and kwargs.
   The substitutions are identified by braces ('{' and '}').
   """
   pass

  def format_map(self, mapping): # real signature unknown; restored from __doc__
   #格式化，将一个字符串中的占位符替换为指定的值
    test='i am {name}, age{a}'
    v=test.format_map({"name":'Vcc', "a":19})
    print(v)
   """
   S.format_map(mapping) -> str
   
   Return a formatted version of S, using substitutions from mapping.
   The substitutions are identified by braces ('{' and '}').
   """
   return ""

  def index(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
   #用法同find
   例：test="asdfasdfasdf"
    v=test.index('as',6,11) ##>=6 <11 结果8
    print(v)   
   找不到就报错，基本不用
   """
   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.
   """
   return 0

  def isalnum(self, *args, **kwargs): # real signature unknown
   #查看字符串是否只由数字和字，母组成 返回True/False
   """
   Return True if the string is an alpha-numeric string, False otherwise.
   
   A string is alpha-numeric if all characters in the string are alpha-numeric and
   there is at least one character in the string.
   """
   pass

  def isalpha(self, *args, **kwargs): # real signature unknown
   """
   Return True if the string is an alphabetic string, False otherwise.
   
   A string is alphabetic if all characters in the string are alphabetic and there
   is at least one character in the string.
   """
   pass

  def isascii(self, *args, **kwargs): # real signature unknown
   """
   Return True if all characters in the string are ASCII, False otherwise.
   
   ASCII characters have code points in the range U+0000-U+007F.
   Empty string is ASCII too.
   """
   pass

  def isdecimal(self, *args, **kwargs): # real signature unknown
   #判断字符串是否是数字（比较常用）
   """
   Return True if the string is a decimal string, False otherwise.
   
   A string is a decimal string if all characters in the string are decimal and
   there is at least one character in the string.
   """
   pass

  def isdigit(self, *args, **kwargs): # real signature unknown
   #判断字符串是否是数字
   """
   Return True if the string is a digit string, False otherwise.
   
   A string is a digit string if all characters in the string are digits and there
   is at least one character in the string.
   """
   pass

  def isidentifier(self, *args, **kwargs): # real signature unknown
   #用于判断字符串是否是有效的 Python 标识符（字母数字下划线），可用来判断变量名是否合法。
   """
   Return True if the string is a valid Python identifier, False otherwise.
   
   Call keyword.iskeyword(s) to test whether string s is a reserved identifier,
   such as "def" or "class".
   """
   pass

  def islower(self, *args, **kwargs): # real signature unknown
   """判断字符串是否是小写"""
   """
   Return True if the string is a lowercase string, False otherwise.
   
   A string is lowercase if all cased characters in the string are lowercase and
   there is at least one cased character in the string.
   """
   pass

  def isnumeric(self, *args, **kwargs): # real signature unknown
   #判断字符串是否是数字（可识别中文数字）
   """
   Return True if the string is a numeric string, False otherwise.
   
   A string is numeric if all characters in the string are numeric and there is at
   least one character in the string.
   """
   pass

  def isprintable(self, *args, **kwargs): # real signature unknown
   #判断字符串中是否存在不可显示的字符
   \t 制表符
   \n 换行符
   """
   Return True if the string is printable, False otherwise.
   
   A string is printable if all of its characters are considered printable in
   repr() or if it is empty.
   """
   pass

  def isspace(self, *args, **kwargs): # real signature unknown
   #判断是否是空格
   """
   Return True if the string is a whitespace string, False otherwise.
   
   A string is whitespace if all characters in the string are whitespace and there
   is at least one character in the string.
   """
   pass

  def istitle(self, *args, **kwargs): # real signature unknown
   #标题所有单词首字母大写，判断是否是标题
   """
   Return True if the string is a title-cased string, False otherwise.
   
   In a title-cased string, upper- and title-case characters may only
   follow uncased characters and lowercase characters only cased ones.
   """
   pass

  def isupper(self, *args, **kwargs): # real signature unknown
   """
   Return True if the string is an uppercase string, False otherwise.
   
   A string is uppercase if all cased characters in the string are uppercase and
   there is at least one cased character in the string.
   """
   pass

  def join(self, ab=None, pq=None, rs=None): # real signature unknown; restored from __doc__
   #将字符串中的每一个元素与指定分隔符拼接
    test="Vcc"
    v = " ".join(test)
    print(v)
    结果 V c c
   """
   Concatenate any number of strings.
   
   The string whose method is called is inserted in between each given string.
   The result is returned as a new string.
   
   Example: '.'.join(['ab', 'pq', 'rs']) -> 'ab.pq.rs'
   """
   pass

  def ljust(self, *args, **kwargs): # real signature unknown
   #内容左对齐，右侧填充指定字符
    test="Vcc"
    v=test.ljust(20,"*")
    print(v)
   """
   Return a left-justified string of length width.
   
   Padding is done using the specified fill character (default is a space).
   """
   pass

  def lower(self, *args, **kwargs): # real signature unknown
   #英文大写转小写
   """ Return a copy of the string converted to lowercase. """
   pass

  def lstrip(self, *args, **kwargs): # real signature unknown
   """移除指定字符串，有限最多匹配，移除左侧"""
   """
   Return a copy of the string with leading whitespace removed.
   
   If chars is given and not None, remove characters in chars instead.
   """
   pass

  def maketrans(self, *args, **kwargs): # real signature unknown
   """字符的对应替换"""
   例：
    test = "aeiou"
    test1 = "12345"
    m = str.maketrans(test,test1)
    v = "adaisdfoaodjifoansdfliofjwaiefnaidf"
    new = v.translate(m)
    print(new)
   结果：
    1d13sdf414dj3f41nsdfl34fjw132fn13df
   """
   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.
   """
   pass

  def partition(self, *args, **kwargs): # real signature unknown
   """"""
   """
   Partition the string into three parts using the given separator.
   
   This will search for the separator in the string.  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 string
   and two empty strings.
   """
   pass

  def replace(self, *args, **kwargs): # real signature unknown
   """
   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.
   """
   pass

  def rfind(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
   """
   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): # real signature unknown; restored from __doc__
   """
   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.
   """
   return 0

  def rjust(self, *args, **kwargs): # real signature unknown
   #内容右对齐，左侧填充指定字符
    test="Vcc"
    v=test.rjust(20,"*")
    print(v)
   """
   """
   Return a right-justified string of length width.
   
   Padding is done using the specified fill character (default is a space).
   """
   pass

  def rpartition(self, *args, **kwargs): # real signature unknown
   """
   Partition the string into three parts using the given separator.
   
   This will search for the separator in the string, starting at 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 strings
   and the original string.
   """
   pass

  def rsplit(self, *args, **kwargs): # real signature unknown
   """
   Return a list of the words in the string, using sep as the delimiter string.
   
     sep
    The delimiter according which to split the string.
    None (the default value) means split according to any whitespace,
    and discard empty strings from the result.
     maxsplit
    Maximum number of splits to do.
    -1 (the default value) means no limit.
   
   Splits are done starting at the end of the string and working to the front.
   """
   pass

  def rstrip(self, *args, **kwargs): # real signature unknown
   """移除指定字符串，有限最多匹配，移除右侧"""
   """
   Return a copy of the string with trailing whitespace removed.
   
   If chars is given and not None, remove characters in chars instead.
   """
   pass

  def split(self, *args, **kwargs): # real signature unknown
   """分割， maxsplit最多分割几次"""
   """
   Return a list of the words in the string, using sep as the delimiter string.
   
     sep
    The delimiter according which to split the string.
    None (the default value) means split according to any whitespace,
    and discard empty strings from the result.
     maxsplit
    Maximum number of splits to do.
    -1 (the default value) means no limit.
   """
   pass

  def splitlines(self, *args, **kwargs): # real signature unknown
   """
   Return a list of the lines in the string, breaking at line boundaries.
   
   Line breaks are not included in the resulting list unless keepends is given and
   true.
   """
   pass

  def startswith(self, prefix, start=None, end=None): # real signature unknown; restored from __doc__
   #查看字符串是否以某个字符串开头，返回True/False
   """
   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, *args, **kwargs): # real signature unknown
   """移除指定字符串，有限最多匹配，移除左右两侧"""
   """
   Return a copy of the string with leading and trailing whitespace removed.
   
   If chars is given and not None, remove characters in chars instead.
   """
   pass

  def swapcase(self, *args, **kwargs): # real signature unknown
   """ Convert uppercase characters to lowercase and lowercase characters to uppercase. """
   pass

  def title(self, *args, **kwargs): # real signature unknown
   #将字符串转化为标题，所有单词首字母大写
   """
   Return a version of the string where each word is titlecased.
   
   More specifically, words start with uppercased characters and all remaining
   cased characters have lower case.
   """
   pass

  def translate(self, *args, **kwargs): # real signature unknown
   """maketrans() 方法用于创建字符映射的转换表，对于接受两个参数的最简单的调用方式，第一个参数是字符串，表示需要转换的字符，第二个参数也是字符串表示转换的目标。
    两个字符串的长度必须相同，为一一对应的关系。"""
    str = "this is string example....wow!!!"
    intab = "aeiou"
    outtab = "12345"
    trantab = str.maketrans(intab,outtab)
    print(str.translate(trantab))

   """
   Replace each character in the string using the given translation table.
   
     table
    Translation table, which must be a mapping of Unicode ordinals to
    Unicode ordinals, strings, or None.
   
   The table must implement lookup/indexing via __getitem__, for instance a
   dictionary or list.  If this operation raises LookupError, the character is
   left untouched.  Characters mapped to None are deleted.
   """
   pass

  def upper(self, *args, **kwargs): # real signature unknown
   """ Return a copy of the string converted to uppercase. """
   pass

  def zfill(self, *args, **kwargs): # real signature unknown
   """内容填充，不能指定字符默认用0填充""" 基本不用
   """
   Pad a numeric string with zeros on the left, to fill a field of the given width.
   
   The string is never truncated.
   """
   pass
   
  常用：join split find strip upper lower replace
    
   for循环
   
   
  字符串一旦创建，不可修改
  一旦修改或者拼接，都会重新生成字符串