python基础 数据类型

python3类的方法

对于Python，一切事物都是对象，对象基于类创建。

一、python运算符

1、结果是值

　　算数运算符：例：a=10+1

　　赋值运算符：例：a=a+1

2、结果是布尔值

　　比较运算：例：a=1>2

　　逻辑运算：例：a=1>2 or 1==1

　　成员运算：例：a='李' in '李维他‘

 二、数据类型

python主要的数据类型主要包括以下几种类型：

(1) 数字型 ：int

(2) 字符串：str

(3) bool型：bool

(4) 列表：list

(5) 元组 ：tuple

(6) 字典：dict

对象的所有功能都放在类里，例如：数字都放在int里，字符串都放在str里...

三、数字型(int)

数字运算符

+       加法运算                                                                                  
-        减法运算
*       乘法运算
/　　除法运算
**　　幂、次方 
//　　取余

%　　取整数、取商

1、定义

如：a = 1234

数字型的全部函数如下，每个数字都有全部功能：

class int(object):
    """
    int(x=0) -> integer
    int(x, base=10) -> integer
    
    Convert a number or string to an integer, or return 0 if no arguments
    are given.  If x is a number, return x.__int__().  For floating point
    numbers, this truncates towards zero.
    
    If x is not a number or if base is given, then x must be a string,
    bytes, or bytearray instance representing an integer literal in the
    given base.  The literal can be preceded by '+' or '-' and be surrounded
    by whitespace.  The base defaults to 10.  Valid bases are 0 and 2-36.
    Base 0 means to interpret the base from the string as an integer literal.
    >>> int('0b100', base=0)
    4
    """
    def bit_length(self): # real signature unknown; restored from __doc__
        """
        int.bit_length() -> int
        
        Number of bits necessary to represent self in binary.
        >>> bin(37)
        '0b100101'
        >>> (37).bit_length()
        6
        """
        return 0

    def conjugate(self, *args, **kwargs): # real signature unknown
        """ Returns self, the complex conjugate of any int. """
        pass

    @classmethod # known case
    def from_bytes(cls, bytes, byteorder, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
        """
        int.from_bytes(bytes, byteorder, *, signed=False) -> int
        
        Return the integer represented by the given array of bytes.
        
        The bytes argument must be a bytes-like object (e.g. bytes or bytearray).
        
        The byteorder argument determines the byte order used to represent the
        integer.  If byteorder is 'big', the most significant byte is at the
        beginning of the byte array.  If byteorder is 'little', the most
        significant byte is at the end of the byte array.  To request the native
        byte order of the host system, use `sys.byteorder' as the byte order value.
        
        The signed keyword-only argument indicates whether two's complement is
        used to represent the integer.
        """
        pass

    def to_bytes(self, length, byteorder, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
        """
        int.to_bytes(length, byteorder, *, signed=False) -> bytes
        
        Return an array of bytes representing an integer.
        
        The integer is represented using length bytes.  An OverflowError is
        raised if the integer is not representable with the given number of
        bytes.
        
        The byteorder argument determines the byte order used to represent the
        integer.  If byteorder is 'big', the most significant byte is at the
        beginning of the byte array.  If byteorder is 'little', the most
        significant byte is at the end of the byte array.  To request the native
        byte order of the host system, use `sys.byteorder' as the byte order value.
        
        The signed keyword-only argument determines whether two's complement is
        used to represent the integer.  If signed is False and a negative integer
        is given, an OverflowError is raised.
        """
        pass

    def __abs__(self, *args, **kwargs): # real signature unknown
        """ abs(self) """
        pass

    def __add__(self, *args, **kwargs): # real signature unknown
        """ Return self+value. """
        pass

    def __and__(self, *args, **kwargs): # real signature unknown
        """ Return self&value. """
        pass

    def __bool__(self, *args, **kwargs): # real signature unknown
        """ self != 0 """
        pass

    def __ceil__(self, *args, **kwargs): # real signature unknown
        """ Ceiling of an Integral returns itself. """
        pass

    def __divmod__(self, *args, **kwargs): # real signature unknown
        """ Return divmod(self, value). """
        pass

    def __eq__(self, *args, **kwargs): # real signature unknown
        """ Return self==value. """
        pass

    def __float__(self, *args, **kwargs): # real signature unknown
        """ float(self) """
        pass

    def __floordiv__(self, *args, **kwargs): # real signature unknown
        """ Return self//value. """
        pass

    def __floor__(self, *args, **kwargs): # real signature unknown
        """ Flooring an Integral returns itself. """
        pass

    def __format__(self, *args, **kwargs): # real signature unknown
        pass

    def __getattribute__(self, *args, **kwargs): # real signature unknown
        """ Return getattr(self, name). """
        pass

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass

    def __ge__(self, *args, **kwargs): # real signature unknown
        """ Return self>=value. """
        pass

    def __gt__(self, *args, **kwargs): # real signature unknown
        """ Return self>value. """
        pass

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

    def __index__(self, *args, **kwargs): # real signature unknown
        """ Return self converted to an integer, if self is suitable for use as an index into a list. """
        pass

    def __init__(self, x, base=10): # known special case of int.__init__
        """
        int(x=0) -> integer
        int(x, base=10) -> integer
        
        Convert a number or string to an integer, or return 0 if no arguments
        are given.  If x is a number, return x.__int__().  For floating point
        numbers, this truncates towards zero.
        
        If x is not a number or if base is given, then x must be a string,
        bytes, or bytearray instance representing an integer literal in the
        given base.  The literal can be preceded by '+' or '-' and be surrounded
        by whitespace.  The base defaults to 10.  Valid bases are 0 and 2-36.
        Base 0 means to interpret the base from the string as an integer literal.
        >>> int('0b100', base=0)
        4
        # (copied from class doc)
        """
        pass

    def __int__(self, *args, **kwargs): # real signature unknown
        """ int(self) """
        pass

    def __invert__(self, *args, **kwargs): # real signature unknown
        """ ~self """
        pass

    def __le__(self, *args, **kwargs): # real signature unknown
        """ Return self<=value. """
        pass

    def __lshift__(self, *args, **kwargs): # real signature unknown
        """ Return self<<value. """
        pass

    def __lt__(self, *args, **kwargs): # real signature unknown
        """ Return self<value. """
        pass

    def __mod__(self, *args, **kwargs): # real signature unknown
        """ Return self%value. """
        pass

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

    def __neg__(self, *args, **kwargs): # real signature unknown
        """ -self """
        pass

    @staticmethod # known case of __new__
    def __new__(*args, **kwargs): # real signature unknown
        """ Create and return a new object.  See help(type) for accurate signature. """
        pass

    def __ne__(self, *args, **kwargs): # real signature unknown
        """ Return self!=value. """
        pass

    def __or__(self, *args, **kwargs): # real signature unknown
        """ Return self|value. """
        pass

    def __pos__(self, *args, **kwargs): # real signature unknown
        """ +self """
        pass

    def __pow__(self, *args, **kwargs): # real signature unknown
        """ Return pow(self, value, mod). """
        pass

    def __radd__(self, *args, **kwargs): # real signature unknown
        """ Return value+self. """
        pass

    def __rand__(self, *args, **kwargs): # real signature unknown
        """ Return value&self. """
        pass

    def __rdivmod__(self, *args, **kwargs): # real signature unknown
        """ Return divmod(value, self). """
        pass

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

    def __rfloordiv__(self, *args, **kwargs): # real signature unknown
        """ Return value//self. """
        pass

    def __rlshift__(self, *args, **kwargs): # real signature unknown
        """ Return value<<self. """
        pass

    def __rmod__(self, *args, **kwargs): # real signature unknown
        """ Return value%self. """
        pass

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

    def __ror__(self, *args, **kwargs): # real signature unknown
        """ Return value|self. """
        pass

    def __round__(self, *args, **kwargs): # real signature unknown
        """
        Rounding an Integral returns itself.
        Rounding with an ndigits argument also returns an integer.
        """
        pass

    def __rpow__(self, *args, **kwargs): # real signature unknown
        """ Return pow(value, self, mod). """
        pass

    def __rrshift__(self, *args, **kwargs): # real signature unknown
        """ Return value>>self. """
        pass

    def __rshift__(self, *args, **kwargs): # real signature unknown
        """ Return self>>value. """
        pass

    def __rsub__(self, *args, **kwargs): # real signature unknown
        """ Return value-self. """
        pass

    def __rtruediv__(self, *args, **kwargs): # real signature unknown
        """ Return value/self. """
        pass

    def __rxor__(self, *args, **kwargs): # real signature unknown
        """ Return value^self. """
        pass

    def __sizeof__(self, *args, **kwargs): # real signature unknown
        """ Returns size in memory, in bytes """
        pass

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

    def __sub__(self, *args, **kwargs): # real signature unknown
        """ Return self-value. """
        pass

    def __truediv__(self, *args, **kwargs): # real signature unknown
        """ Return self/value. """
        pass

    def __trunc__(self, *args, **kwargs): # real signature unknown
        """ Truncating an Integral returns itself. """
        pass

    def __xor__(self, *args, **kwargs): # real signature unknown
        """ Return self^value. """
        pass

    denominator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the denominator of a rational number in lowest terms"""

    imag = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the imaginary part of a complex number"""

    numerator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the numerator of a rational number in lowest terms"""

    real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """the real part of a complex number"""

例如：def center(self, width, fillchar=None) 

　　其中，def代表定义一个函数；其中参数未写 ‘=‘号的表示定义，给出值；写’=‘号的，可不写，为默认值。

　　如：v = test.center(20, "*”） # 设置宽度为20，并将test内容在20宽度内居中，其他位置用*填充(未写占位符时用空格填充)。*******1234********

2、常用的几个重要函数：

四、字符串(str)

字符串运算符

+       字符串连接(拼接)                                                                             a+b
*        重复输出字符串                  　　　　　　　　　　　　　　　　   abc*3
[]       通过索引获取字符串中字符                　　　　　　　　　　　　  a[1] 
[ : ]    截取字符串中的一部分，也成为切片                                               a[1:4] 
in      成员运算符 -判断a是否包含b　　　　　　　　　　　　                b in a 
not in  成员运算符 - 判断a是否不包含c　　　　　　　　　　　　　  　c not in a 

1、定义

如：a = '123'、b='12ac'、c='abcd'

2、字符串的全部功能函数如下：

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): # real signature unknown; restored from __doc__
        """
        S.capitalize() -> str
        
        Return a capitalized version of S, i.e. make the first character
        have upper case and the rest lower case.
        """
        return ""

    def casefold(self): # real signature unknown; restored from __doc__
        """
        S.casefold() -> str
        
        Return a version of S suitable for caseless comparisons.
        """
        return ""

    def center(self, width, fillchar=None): # real signature unknown; restored from __doc__
        """
        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)
        """
        return ""

    def count(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
        """
        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, encoding='utf-8', errors='strict'): # real signature unknown; restored from __doc__
        """
        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.
        """
        return b""

    def endswith(self, suffix, start=None, end=None): # real signature unknown; restored from __doc__
        """
        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=8): # real signature unknown; restored from __doc__
        """
        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.
        """
        return ""

    def find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
        """
        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
        """
        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__
        """
        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__
        """
        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): # real signature unknown; restored from __doc__
        """
        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): # real signature unknown; restored from __doc__
        """
        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 isdecimal(self): # real signature unknown; restored from __doc__
        """
        S.isdecimal() -> bool
        
        Return True if there are only decimal characters in S,
        False otherwise.
        """
        return False

    def isdigit(self): # real signature unknown; restored from __doc__
        """
        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 isidentifier(self): # real signature unknown; restored from __doc__
        """
        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".
        """
        return False

    def islower(self): # real signature unknown; restored from __doc__
        """
        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 isnumeric(self): # real signature unknown; restored from __doc__
        """
        S.isnumeric() -> bool
        
        Return True if there are only numeric characters in S,
        False otherwise.
        """
        return False

    def isprintable(self): # real signature unknown; restored from __doc__
        """
        S.isprintable() -> bool
        
        Return True if all characters in S are considered
        printable in repr() or S is empty, False otherwise.
        """
        return False

    def isspace(self): # real signature unknown; restored from __doc__
        """
        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): # real signature unknown; restored from __doc__
        """
        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.
        """
        return False

    def isupper(self): # real signature unknown; restored from __doc__
        """
        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): # real signature unknown; restored from __doc__
        """
        S.join(iterable) -> str
        
        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): # real signature unknown; restored from __doc__
        """
        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).
        """
        return ""

    def lower(self): # real signature unknown; restored from __doc__
        """
        S.lower() -> str
        
        Return a copy of the string S converted to lowercase.
        """
        return ""

    def lstrip(self, chars=None): # real signature unknown; restored from __doc__
        """
        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.
        """
        return ""

    def maketrans(self, *args, **kwargs): # real signature unknown
        """
        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, sep): # real signature unknown; restored from __doc__
        """
        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): # real signature unknown; restored from __doc__
        """
        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.
        """
        return ""

    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, width, fillchar=None): # real signature unknown; restored from __doc__
        """
        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).
        """
        return ""

    def rpartition(self, sep): # real signature unknown; restored from __doc__
        """
        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=-1): # real signature unknown; restored from __doc__
        """
        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.
        """
        return []

    def rstrip(self, chars=None): # real signature unknown; restored from __doc__
        """
        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.
        """
        return ""

    def split(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__
        """
        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.
        """
        return []

    def splitlines(self, keepends=None): # real signature unknown; restored from __doc__
        """
        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.
        """
        return []

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

    def swapcase(self): # real signature unknown; restored from __doc__
        """
        S.swapcase() -> str
        
        Return a copy of S with uppercase characters converted to lowercase
        and vice versa.
        """
        return ""

    def title(self): # real signature unknown; restored from __doc__
        """
        S.title() -> str
        
        Return a titlecased version of S, i.e. words start with title case
        characters, all remaining cased characters have lower case.
        """
        return ""

    def translate(self, table): # real signature unknown; restored from __doc__
        """
        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.
        """
        return ""

    def upper(self): # real signature unknown; restored from __doc__
        """
        S.upper() -> str
        
        Return a copy of S converted to uppercase.
        """
        return ""

    def zfill(self, width): # real signature unknown; restored from __doc__
        """
        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.
        """
        return ""

    def __add__(self, *args, **kwargs): # real signature unknown
        """ Return self+value. """
        pass

    def __contains__(self, *args, **kwargs): # real signature unknown
        """ Return key in self. """
        pass

    def __eq__(self, *args, **kwargs): # real signature unknown
        """ Return self==value. """
        pass

    def __format__(self, format_spec): # real signature unknown; restored from __doc__
        """
        S.__format__(format_spec) -> str
        
        Return a formatted version of S as described by format_spec.
        """
        return ""

    def __getattribute__(self, *args, **kwargs): # real signature unknown
        """ Return getattr(self, name). """
        pass

    def __getitem__(self, *args, **kwargs): # real signature unknown
        """ Return self[key]. """
        pass

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass

    def __ge__(self, *args, **kwargs): # real signature unknown
        """ Return self>=value. """
        pass

    def __gt__(self, *args, **kwargs): # real signature unknown
        """ Return self>value. """
        pass

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

    def __init__(self, value='', encoding=None, errors='strict'): # known special case of str.__init__
        """
        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'.
        # (copied from class doc)
        """
        pass

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

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

    def __le__(self, *args, **kwargs): # real signature unknown
        """ Return self<=value. """
        pass

    def __lt__(self, *args, **kwargs): # real signature unknown
        """ Return self<value. """
        pass

    def __mod__(self, *args, **kwargs): # real signature unknown
        """ Return self%value. """
        pass

    def __mul__(self, *args, **kwargs): # real signature unknown
        """ Return self*value.n """
        pass

    @staticmethod # known case of __new__
    def __new__(*args, **kwargs): # real signature unknown
        """ Create and return a new object.  See help(type) for accurate signature. """
        pass

    def __ne__(self, *args, **kwargs): # real signature unknown
        """ Return self!=value. """
        pass

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

    def __rmod__(self, *args, **kwargs): # real signature unknown
        """ Return value%self. """
        pass

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

    def __sizeof__(self): # real signature unknown; restored from __doc__
        """ S.__sizeof__() -> size of S in memory, in bytes """
        pass

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

3、常见的几个重要函数

1.  查看变量类型、转换

1 a = '1234'                # 定义字符串
2 print(type(a), a)         # 输出(查看)变量类型，并输出变量值
3 b = int(a)                # 讲字符串转化为数字(字符串必须全是数字才行)
4 print(type(b),b)

　　2.  改变字符串的二进制表示位数后数是多少

num = '011'
v = int(num, base=8)　　#将num转换为数字，且是8进制数，不设置base默认是10进制
print(v)

 

 

　　3.  英文字母大小写转换

 

 

a = 'aedSJFwe123'
v = a.islower()     # 判断字符串中字母是否全是小写
v1 = a.lower()      # 将字符全部转换为小写,仅对 ASCII 编码的小写有效
v2 = a.casefold()   # 将字符串转换成小写，Unicode 编码中凡是有对应的小写形式的，都会转换。
print(v, v1, v2)
n = a.isupper()     # 判断字符串中字母是否全是大写
n1 = a.upper()      # 将字母全部转换为大写
n2 = a.swapcase()   # 将大小写反转。
print(n, n1, n2)

　　4.  count(self, sub, start=None, end=None) #去字符串中寻找，子序列出现的次数。统计字符串中包含子串的个数。

test = 'alexAlex'
v = test.count('ex')
v1 = test.count('ex', 1, 6)  # 后面两位是查找字符的区间，大于等于1小于6(起始位为0)。
print(v, v1)

结果为：
2 1

　　5.  find() #从开始往后找，找到第一个，获取其位置

v3 = test.find('ex')        #找不到时，为错误，输出-1
v4 = test.find('ex',5,8)  #后两位是查找区间（也可说成切片）代表>=5,<8。

　　6.  format(*args, *kwargs)  #格式化，将一个字符串中的占位符替换为指定的值。

　　　　1、test = ’i am {name}, age {a}'

　　　　　  v = test.format(name='xiaoming', a=19)  # 其中{name}中name为占位符的名字。

　　　结果为：v= i am alex, age 19

　　　  2、test = ’i am {1}, age {2}'

　　　　    v = test.format('xiaoming', 19, 12, 13)  # 其中占位符{}中，若为数字，则是从0开始写，否则替换内容数量得大于占位符中的数字。替换时，替换的内容从0还是对应。

　　　结果为：v= i am 19, age 12

　　7.  fomat_map(self, mapping)

　　　 v=test.format_map({'name':'alex', 'a'=19}) 　　#格式化，传入的值'name':'alex', 'a'=19，成对对应。

　　8.  isalnum()   #判断字符串中是否只包含字符和数字

　　     v = test.isalnum()  # 返回值为true、false。

　　9.  center ()、rjust()、ljust()：根据显示的长度中间对齐、左对齐、右对齐，不足的部分根据指定内容填充,默认为空格。

　　10.  expandtabs()　 # 断句 　　　　

　　　　test = 'username\temail\tpasswd\nLL\tqq.com\t123\n'  # \t制表符，断句；\n换行符。
　　　　v = test.expandtabs(20)　　　　#以20个字符断句，不够20，空格补够20位。
　　　　print(v)　　　　

　　　　username            email               passwd
　　　　LL                  qq.com              123

　　11.  字符串内容判断

　　test = 'ada女人二'　　　　# 定义字符串
　　v = test.isalpha()      # 判断字符串是否只包含文字字符，字符串仅包含中文字符也合法
　　v1 = test.isalnum()     # 判断字符串是否只包含文字和数字字符，字符串仅包含中文字符合法。若字符串包含空格、下划线、~等非文字数字式字符，均返回False。
　　v2 = test.isdecimal()   # 是否只有：数字(10进制数字)。
　　v3 = test.isdigit()     # 是否只有：数字，包含特殊数字如小标题数字。
　　v4 = test.isnumeric()   # 是否只有：数字，更能识别中文数字二
　　v5 = test.isidentifier()  # 判断是否符合标识符：字母、数字、下划线，不能开头数字。
　　v6 = test.isprintable()   # 判断字符串是否是合法的标识符(文字、数字、下划线)字符串仅包含中文字符合法，实际上这里判断的是变量名是否合法。
　　print(v, v1, v2, v3, v4, v5, v6)
　　结果是：True True False False False True True

　　v7 = test.isupper()       # 字母是否都是大写
　　v8 = test.islower()       # 字母是否都是小写
　　v9 = test.istitle()       # 是否是标题，即每个单词首字母大写
　　v10 = test.isspace()      # 字符串是否都为空格，空格和没内容不一样
　　print(v7, v8, v9, v10)　　　

　　12.  swapcase()　　#将字母大小写反转

　　13.  title()　　#将字符串转换为标题形式，即买个单词首字母大写，其余小写

　　title()：字符串中每个单词的首字母大写，其余小写。单词的首字符为非字母字符也不影响转换。字符串仅包含非字母字符合法，但返回原字符串。如：
　　'ab cd'.title() -->'Ab Cd' 　　#字符串中每个单词的首字母大写
　　'中国ab 123cd'.title() -->'中国Ab 123Cd' 　　#即使首字符为非字母字符，也可以进行转换
　　'中国 123'.title() -->'中国 123'

　　capitalize()：字符串首字母大写，其余小写。如果字符串首字符为非字母字符，将返回原字符串。字符串仅包含非字母字符合法，但返回原字符串。如：
　　'ab cd'.capitalize() -->'Ab cd' 　　#只转换字符串的首字母
　　'中国ab 123cd'.capitalize() -->'中国ab 123cd' 　　#首字符为非字母字符，返回原字符串
　　'中国 123'.capitalize() -->'中国 123' 　　#不会报错，返回原字符串

　　14.  join()　　#将字符串中的每个元素按指定分隔符进行连接

　　test = '好好学习天天向上'
　　t = '*'
　　v = t.join(test)  # 或者v= '*'.join(test)
　　print(v)
结果是：好*好*学*习*天*天*向*上

　　15.  lstrip(chars)　　#chars参数是一个字符串，它包含了所有将要被移除的字符的集合,从左边(头)开始，遇到第一个非chars字符则停止。默认为空格。

　　　　其中rstrip()、strip()分别从字符串的右边(尾)、两边开始匹配。

test = '123a2325dsjiu12342312312'
v = test.strip('123')  #从原字符串的两边开始，匹配chars里包含的所有字符，直至遇到第一个非chars字符为止，原字符串中匹配到的所有字符都被移除。
print(v)
结果为：a2325dsjiu1234

　　16. 总结：

　　　　6个基本方法：join()、split()、find()、strip()、upper()、lower()

　　　　4个常用方法：len()、for循环、索引、切片

　　　1、v = test[2]　　# 索引下标，获取字符串中的某一个(或某范围)元素。

　　　2、 v = test[0:2]　　# 切片取值为，第一个元素为0，第n个下标为n-1（最后一个，也可也写为-1，表示倒数第1个）。切片范围：第一个数表示为大于等于第0个，第二个为小于第2个。

　　　　　　　　　　　# v = test[0:-1]　　#表示除了最后一个，其他都取。若想取尾，则不写就行，比如取全部为：test[0:]或test[:]

　　　3、v = len(test)　　# 字符串共有几个字符组成。（Py3和py2不同） 

　　　　　　len(li)　　 # 列表有几个元素组成，以列表中的‘,’为分隔符（li为列表）

　　　4、for in 循环

　　　　for  变量名  in 字符串：

　　　　test = '你还认识我吗'
　　　　num = 0
　　　　for v in test:
 　　   print(v)
　　　　或while num < len(test):
 　　   v1 = test[num]
  　　  num = num + 1
  　　  print(v1)

　　　　其中v 和v1结果是一样的，是两种方法。输出字符串的每个元素，每个元素为一行。

　　17.  replace()　　替换 

　　test = '1232423112241234'
　　v = test.maketrans('12', 'ab', '5')　　# 对字符串test做映射表，即：把1映射到a,2映射到b,然后给translate()使用，做替换。第三个参数‘5’被映射成None,即为空，如果字符串中有5，则把所有5删除。最多有3个参数。
　　v1 = test.translate(v)　　　　　　　　　# 利用maketrans做的映射，替换字符。
　　v2 = test.replace('12', 'abc')　　　　# 第一个是被替换的字符串，第二个是替换的，字符串可不等长
　　v3 = test.replace('12', 'abc', 2)　　# 第三个参数，表示替换掉几个，默认全部替换掉
　　print(v, v1, v2, v3)
　　结果为：{49: 97, 50: 98, 53: None} ab3b4b3aabb4ab34 abc324231abc24abc34 abc324231abc241234
v4 = test.translate(test.maketrans('12', 'ab', '5'))　　# v4和v1的结果是一样的，一般都是连写。最多有3个参数。
maktrans 最多有3个参数。是一个静态方法，用于生成一个对照表，以供 translate 使用。
如果 maktrans 仅一个参数，则该参数必须是一个字典，字典的key要么是一个 Unicode 编码（一个整数），要么是一个长度为 1 的字符串，字典的 value 则可以是任意字符串、None或者 Unicode 编码。
如果 maktrans 有两个参数，则两个参数形成映射，且两个字符串必须是长度相等；
如果有第三个参数，则第三个参数也必须是字符串，该字符串将自动映射到 None：

 　　18.  分隔字符串  

　　　　test=‘abcd123abcd123'

　　　　1、partition('c')、rpartition()　　# 结果为元组 ()，不写参数时默认为空格。

　　　　partition('c')　　# 将以分隔符‘c’，把字符串分隔为三份，且从左边起遇到第一个c分隔，即(’ab'、'c'、‘123abcd')。rpartition()则是从右边开始查找。

　　　　当查找不到字符时，则会在结尾处添加两个空字符。如partition('s'),则为（‘abcd123abcd123','',''）

　　　　2、split()　　# 分隔符会被删除，第二个参数分隔几个字符，返回的是列表。如split('c',3)

　　　　　rsplit()　　# 从右边开始。

　　　　　splitlines()　　#以换行符为分隔，拆分一个包含多行的字符串，以每行为一个元素返回一个列表。如果字符串不是多行的，则返回整个字符串为列表的一个元素。

　　　　3、startswith(self, prefix, start=None, end=None) 　　# 判断字符串是否以指定后缀开始，返回True或False。start和end指定判断的起始范围，默认全字符串。

　　　　　endswith(self, suffix, start=None, end=None)　　# 判断字符串是否以指定后缀开始

 

 先整理到这，后续回继续整理。

关于python3的运算符可以参考这篇文章：https://www.cnblogs.com/aiwanbuhui/p/7903957.html