Python学习第二天，,我们为什么学习Pyt

Python学习第二天，,我们为什么学习Pyt

我们为什么学习Python呢？为什么是Python而不是其他语言呢？

C和Python、java、C#等

C语言：代码编译得到机器码，机器码在处理上直接执行，每一条指令控制CPU工作。

其他语言：代码编译得到字节码，虚拟机执行字节码转换成机器码再在处理器上执行

Python和CPython：这门语言是由C开发而来

对于使用：Python的类库齐全并且使用简洁，如果要实现同样的功能，Python 10行代码可以解决，C可能就需要100行甚至更多。

对于速度：Python的运行速度相较于C，是慢了。

Python和Java、C#等

对于使用：Linux原装Python，其他语言没有，以上几门语言都有非常丰富的类库支持

对于速度：Python在速度上可能稍显逊色

所以，Python和其他语言没有什么本质区别，其他区别在于，擅长某领域、人才丰富、先入为主。

那么Python的种类有哪些呢？

这里我们举几个Python的几个种类：

cPython 比如打印‘alex’时， print(‘alex’) c解释器解释成 .pyc（字节码）-> 机器码 cpu

jPython print(‘alex’) java解释器解释成 java（字节码）-> 机器码 cpu

ironPython print(‘alex’) c#解释器解释成 c#（字节码）-> 机器码 cpu

也就是它们运行的内部原理是不同的。

老师说pypy早晚会火的啊！这是因为它在编译的时候就生成了机器码。

.pyc文件

执行Python代码时，如果导入了其他的.py文件，那么，执行过程中会自动生成一个与其同名的.pyc文件，该文件就是Python解释器编译之后的字节码。

代码经过编译可以产生字节码；字节码通过反编译也可以得到代码。

例子：建两个文件 index.py和lib.py 首先在lib里print(‘lib’)

在index里

import lib

print(‘index’) 这个时候就产生了lib.pyc文件！

基本的数据类型：（这是重点哦！）

因此str是类，int是类，dict、list、tuple等等都是类。

“guojingjing”、99、{‘北京‘,‘上海‘,‘广州‘,‘深圳‘}是分别根据str类、int类和dict类生成的。

在这里介绍2种查看类中成员的方法：1、首先，需要装python，然后至少要有个命令行窗口：dir(类名)2、在Pycharm中输入类名比如str，左手按住ctrl键的同时鼠标变成小手时点击该类名就可以了。

对于方法1（这里以类str为例）其结果是：

对于方法2（这里以类str为例）其结果是：

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(*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                Like S.find() but raise 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                Like S.rfind() but raise 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

在python中，还有一个“help(类名.方法名)”方法：可以查看类的详细功能；“help(类名.功能名)”：查看类中某功能的详细情况

>>> help(str)Help on class str in module __builtin__: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. |   |  Method resolution order: |      str |      basestring |      object |   |  Methods defined here: |   |  __add__(...) |      x.__add__(y) <==> x+y |   |  __contains__(...) |      x.__contains__(y) <==> y in x |   |  __eq__(...) |      x.__eq__(y) <==> x==y |   |  __format__(...) |      S.__format__(format_spec) -> string |       |      Return a formatted version of S as described by format_spec. |   |  __ge__(...) |      x.__ge__(y) <==> x>=y |   |  __getattribute__(...) |      x.__getattribute__(‘name‘) <==> x.name |   |  __getitem__(...) |      x.__getitem__(y) <==> x[y] |   |  __getnewargs__(...) |   |  __getslice__(...) |      x.__getslice__(i, j) <==> x[i:j] |       |      Use of negative indices is not supported. |   |  __gt__(...) |      x.__gt__(y) <==> x>y |   |  __hash__(...) |      x.__hash__() <==> hash(x) |   |  __le__(...) |      x.__le__(y) <==> x<=y |   |  __len__(...) |      x.__len__() <==> len(x) |   |  __lt__(...) |      x.__lt__(y) <==> x<y |   |  __mod__(...) |      x.__mod__(y) <==> x%y |   |  __mul__(...) |      x.__mul__(n) <==> x*n |   |  __ne__(...) |      x.__ne__(y) <==> x!=y |   |  __repr__(...) |      x.__repr__() <==> repr(x) |   |  __rmod__(...) |      x.__rmod__(y) <==> y%x |   |  __rmul__(...) |      x.__rmul__(n) <==> n*x |   |  __sizeof__(...) |      S.__sizeof__() -> size of S in memory, in bytes |   |  __str__(...) |      x.__str__() <==> str(x) |   |  capitalize(...) |      S.capitalize() -> string |       |      Return a copy of the string S with only its first character |      capitalized. |   |  center(...) |      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) |   |  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. |   |  decode(...) |      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. |   |  encode(...) |      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. |   |  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]) -> 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. |   |  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) -> string |       |      Return a formatted version of S, using substitutions from args and kwargs. |      The substitutions are identified by braces (‘{‘ and ‘}‘). |   |  index(...) |      S.index(sub [,start [,end]]) -> int |       |      Like S.find() but raise 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. |   |  isdigit(...) |      S.isdigit() -> bool |       |      Return True if all characters in S are digits |      and there is at least one character in S, False otherwise. |   |  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. |   |  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. uppercase 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) -> string |       |      Return a string which is the concatenation of the strings in the |      iterable.  The separator between elements is S. |   |  ljust(...) |      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). |   |  lower(...) |      S.lower() -> string |       |      Return a copy of the string S converted to lowercase. |   |  lstrip(...) |      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 |   |  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]) -> 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. |   |  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 |       |      Like S.rfind() but raise ValueError when the substring is not found. |   |  rjust(...) |      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) |   |  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 [,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. |   |  rstrip(...) |      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 |   |  split(...) |      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. |   |  splitlines(...) |      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. |   |  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]) -> 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 |   |  swapcase(...) |      S.swapcase() -> string |       |      Return a copy of the string S with uppercase characters |      converted to lowercase and vice versa. |   |  title(...) |      S.title() -> string |       |      Return a titlecased version of S, i.e. words start with uppercase |      characters, all remaining cased characters have lowercase. |   |  translate(...) |      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. |   |  upper(...) |      S.upper() -> string |       |      Return a copy of the string S converted to uppercase. |   |  zfill(...) |      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. |   |  ---------------------------------------------------------------------- |  Data and other attributes defined here: |   |  __new__ = <built-in method __new__ of type object> |      T.__new__(S, ...) -> a new object with type S, a subtype of T

其他的类都可以用同样的方法查看其包含的成员，并且可以查看类中某成员的功能。

一、整数

其具备的功能：

其源码为：

class int(object):    """    int(x=0) -> int or long    int(x, base=10) -> int or long        Convert a number or string to an integer, or return 0 if no arguments    are given.  If x is floating point, the conversion truncates towards zero.    If x is outside the integer range, the function returns a long instead.        If x is not a number or if base is given, then x must be a string or    Unicode object 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__        """返回表示该数字时所用的最小位数        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        """返回一个复数的共轭复数         Returns self, the complex conjugate of any int. """        pass    def __abs__(self): # real signature unknown; restored from __doc__        """ 返回绝对值        x.__abs__() <==> abs(x) """        pass    def __add__(self, y): # real signature unknown; restored from __doc__        """ 返回两个数的和        x.__add__(y) <==> x+y """        pass    def __and__(self, y): # real signature unknown; restored from __doc__        """ 返回两个数按位与的结果        x.__and__(y) <==> x&y """        pass    def __cmp__(self, y): # real signature unknown; restored from __doc__        """返回两个数比较的结果，参数从左至右（a，b），a>b返回1，a<b返回-1，a=b返回0        x.__cmp__(y) <==> cmp(x,y) """        pass    def __coerce__(self, y): # real signature unknown; restored from __doc__        """a.__coerce__(b),强制返回一个元组（a，b）        x.__coerce__(y) <==> coerce(x, y) """        pass    def __divmod__(self, y): # real signature unknown; restored from __doc__        """ 相除，得到商和余数组成的元组        x.__divmod__(y) <==> divmod(x, y) """        pass    def __div__(self, y): # real signature unknown; restored from __doc__        """返回两数相除的商         x.__div__(y) <==> x/y """        pass    def __float__(self): # real signature unknown; restored from __doc__        """将数据类型强制转换为float        x.__float__() <==> float(x) """        pass    def __floordiv__(self, y): # real signature unknown; restored from __doc__        """ 不保留小数点后的小数除法,也可以用‘//’来表示：a//b，我们亲切地称之为“地板除”！！！        x.__floordiv__(y) <==> x//y """        pass    def __format__(self, *args, **kwargs): # real signature unknown        """ 格式化"""        pass    def __getattribute__(self, name): # real signature unknown; restored from __doc__        """无条件被调用，通过实例访问属性         x.__getattribute__(‘name‘) <==> x.name """        pass    def __getnewargs__(self, *args, **kwargs): # real signature unknown        """ 内部调用 __new__方法或创建对象时传入参数使用 """         pass    def __hash__(self): # real signature unknown; restored from __doc__        """ 如果对象object为哈希表类型，返回对象object的哈希值。哈希值为整数。在字典查找中，哈希值用于快速比较字典的键。两个数值如果相等，则哈希值也相等           x.__hash__() <==> hash(x) """        pass    def __hex__(self): # real signature unknown; restored from __doc__        """ 返回当前数的 十六进制 表示          x.__hex__() <==> hex(x) """        pass    def __index__(self): # real signature unknown; restored from __doc__        """ 用于切片，对数字无意义        x[y:z] <==> x[y.__index__():z.__index__()] """        pass    def __init__(self, x, base=10): # known special case of int.__init__        """构造函数        int(x=0) -> int or long        int(x, base=10) -> int or long                Convert a number or string to an integer, or return 0 if no arguments        are given.  If x is floating point, the conversion truncates towards zero.        If x is outside the integer range, the function returns a long instead.                If x is not a number or if base is given, then x must be a string or        Unicode object 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): # real signature unknown; restored from __doc__        """ 转换为整数        x.__int__() <==> int(x) """        pass    def __invert__(self): # real signature unknown; restored from __doc__        """按位求反        x.__invert__() <==> ~x """        pass    def __long__(self): # real signature unknown; restored from __doc__        """转换为长整数        x.__long__() <==> long(x) """        pass    def __lshift__(self, y): # real signature unknown; restored from __doc__        """ 左移，相对二进制的操作        x.__lshift__(y) <==> x<<y """        pass    def __mod__(self, y): # real signature unknown; restored from __doc__        """ 取余        x.__mod__(y) <==> x%y """        pass    def __mul__(self, y): # real signature unknown; restored from __doc__        """ 返回两数相乘的积        x.__mul__(y) <==> x*y """        pass    def __neg__(self): # real signature unknown; restored from __doc__        """ 返回一个数的负数，个人觉得和相反数没差        x.__neg__() <==> -x """        pass    @staticmethod # known case of __new__    def __new__(S, *more): # real signature unknown; restored from __doc__        """ 创建一个int类的新对象        T.__new__(S, ...) -> a new object with type S, a subtype of T """        pass    def __nonzero__(self): # real signature unknown; restored from __doc__        """ 判断一个数是不是0        x.__nonzero__() <==> x != 0 """        pass    def __oct__(self): # real signature unknown; restored from __doc__        """ 返回该值的 八进制 表示        x.__oct__() <==> oct(x) """        pass    def __or__(self, y): # real signature unknown; restored from __doc__        """ 位运算，或，针对二进制数        x.__or__(y) <==> x|y """        pass    def __pos__(self): # real signature unknown; restored from __doc__        """ 并没什么卵用，说是a.__pos__()，会返回一个+a，但是不管输入整数还是负数，返回值都是他本身，感觉歪果仁真有幽默感        x.__pos__() <==> +x """        pass    def __pow__(self, y, z=None): # real signature unknown; restored from __doc__        """  幂，次方        x.__pow__(y[, z]) <==> pow(x, y[, z]) """        pass    def __radd__(self, y): # real signature unknown; restored from __doc__        """x.__radd__(y) <==> y+x """        pass    def __rand__(self, y): # real signature unknown; restored from __doc__        """x.__rand__(y) <==> y&x """        pass    def __rdivmod__(self, y): # real signature unknown; restored from __doc__        """ x.__rdivmod__(y) <==> divmod(y, x) """        pass    def __rdiv__(self, y): # real signature unknown; restored from __doc__        """ x.__rdiv__(y) <==> y/x """        pass    def __repr__(self): # real signature unknown; restored from __doc__        """ 转化为解释器可读取的形式        x.__repr__() <==> repr(x) """        pass    def __rfloordiv__(self, y): # real signature unknown; restored from __doc__        """        x.__rfloordiv__(y) <==> y//x """        pass    def __rlshift__(self, y): # real signature unknown; restored from __doc__        """ x.__rlshift__(y) <==> y<<x """        pass    def __rmod__(self, y): # real signature unknown; restored from __doc__        """ x.__rmod__(y) <==> y%x """        pass    def __rmul__(self, y): # real signature unknown; restored from __doc__        """ x.__rmul__(y) <==> y*x """        pass    def __ror__(self, y): # real signature unknown; restored from __doc__        """ x.__ror__(y) <==> y|x """        pass    def __rpow__(self, x, z=None): # real signature unknown; restored from __doc__        """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """        pass    def __rrshift__(self, y): # real signature unknown; restored from __doc__        """ x.__rrshift__(y) <==> y>>x """        pass    def __rshift__(self, y): # real signature unknown; restored from __doc__        """ x.__rshift__(y) <==> x>>y """        pass    def __rsub__(self, y): # real signature unknown; restored from __doc__        """ x.__rsub__(y) <==> y-x """        pass    def __rtruediv__(self, y): # real signature unknown; restored from __doc__        """ x.__rtruediv__(y) <==> y/x """        pass    def __rxor__(self, y): # real signature unknown; restored from __doc__        """ x.__rxor__(y) <==> y^x """        pass    def __str__(self): # real signature unknown; restored from __doc__        """ 转换为人阅读的形式，如果没有适于人阅读的解释形式的话，则返回解释器课阅读的形式        x.__str__() <==> str(x) """        pass    def __sub__(self, y): # real signature unknown; restored from __doc__        """ 返回两数相减的差        x.__sub__(y) <==> x-y """        pass    def __truediv__(self, y): # real signature unknown; restored from __doc__        """返回两数相除的商，这里的除是精确的除法，不会省略小数点后的值        x.__truediv__(y) <==> x/y """        pass    def __trunc__(self, *args, **kwargs): # real signature unknown        """返回数值被截取为整形的值，在整形中无意义        Truncating an Integral returns itself. """        pass    def __xor__(self, y): # real signature unknown; restored from __doc__        """ 按位异或        x.__xor__(y) <==> x^y """        pass    denominator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default     """ 分母 = 1 """        """the denominator of a rational number in lowest terms"""    imag = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default    """ 虚数，无意义 """    """the imaginary part of a complex number"""    numerator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default    """ 分子 = 数字大小 """    """the numerator of a rational number in lowest terms"""    real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default    """ 实数，无意义 """    """the real part of a complex number"""                                                      int Code

下面对于老师特别强调以后编程会用到的详细展开一下下：

（1）__abs__():取相反数

a=-12b=10result=a.__abs__()result1=b.__abs__()print(result)print(result1)

　　其输出为：12 10

（2）__add__():相加

a=-19result=a.__add__(100)print(result)

　　在命令窗口是这样的：

（3）__floordiv__:不保留小数点后的小数除法

a=19result=a.__floordiv__(6)print(result)

　　输出的值为3

（4）__init__()：构造方法

创建数字的时候：

age=19或者age=int(19)

　这个时候会自动调用__init__()

（5）__divmod__:返回两个数相除的商和余数组成的元组（商，余数） 应用:显示网页数据中的分页

1 >>> a = 1022 >>> b = 103 >>> a.__divmod__(b)4 (10, 2)

二、长整型

其所有的功能如下：

class long(object):    """    long(x=0) -> long    long(x, base=10) -> long        Convert a number or string to a long integer, or return 0L if no arguments    are given.  If x is floating point, the conversion truncates towards zero.        If x is not a number or if base is given, then x must be a string or    Unicode object 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)    4L    """    def bit_length(self): # real signature unknown; restored from __doc__        """        long.bit_length() -> int or long                Number of bits necessary to represent self in binary.        >>> bin(37L)        ‘0b100101‘        >>> (37L).bit_length()        """        return 0    def conjugate(self, *args, **kwargs): # real signature unknown        """ Returns self, the complex conjugate of any long. """        pass    def __abs__(self): # real signature unknown; restored from __doc__        """ x.__abs__() <==> abs(x) """        pass    def __add__(self, y): # real signature unknown; restored from __doc__        """ x.__add__(y) <==> x+y """        pass    def __and__(self, y): # real signature unknown; restored from __doc__        """ x.__and__(y) <==> x&y """        pass    def __cmp__(self, y): # real signature unknown; restored from __doc__        """ x.__cmp__(y) <==> cmp(x,y) """        pass    def __coerce__(self, y): # real signature unknown; restored from __doc__        """ x.__coerce__(y) <==> coerce(x, y) """        pass    def __divmod__(self, y): # real signature unknown; restored from __doc__        """ x.__divmod__(y) <==> divmod(x, y) """        pass    def __div__(self, y): # real signature unknown; restored from __doc__        """ x.__div__(y) <==> x/y """        pass    def __float__(self): # real signature unknown; restored from __doc__        """ x.__float__() <==> float(x) """        pass    def __floordiv__(self, y): # real signature unknown; restored from __doc__        """ x.__floordiv__(y) <==> x//y """        pass    def __format__(self, *args, **kwargs): # real signature unknown        pass    def __getattribute__(self, name): # real signature unknown; restored from __doc__        """ x.__getattribute__(‘name‘) <==> x.name """        pass    def __getnewargs__(self, *args, **kwargs): # real signature unknown        pass    def __hash__(self): # real signature unknown; restored from __doc__        """ x.__hash__() <==> hash(x) """        pass    def __hex__(self): # real signature unknown; restored from __doc__        """ x.__hex__() <==> hex(x) """        pass    def __index__(self): # real signature unknown; restored from __doc__        """ x[y:z] <==> x[y.__index__():z.__index__()] """        pass    def __init__(self, x=0): # real signature unknown; restored from __doc__        pass    def __int__(self): # real signature unknown; restored from __doc__        """ x.__int__() <==> int(x) """        pass    def __invert__(self): # real signature unknown; restored from __doc__        """ x.__invert__() <==> ~x """        pass    def __long__(self): # real signature unknown; restored from __doc__        """ x.__long__() <==> long(x) """        pass    def __lshift__(self, y): # real signature unknown; restored from __doc__        """ x.__lshift__(y) <==> x<<y """        pass    def __mod__(self, y): # real signature unknown; restored from __doc__        """ x.__mod__(y) <==> x%y """        pass    def __mul__(self, y): # real signature unknown; restored from __doc__        """ x.__mul__(y) <==> x*y """        pass    def __neg__(self): # real signature unknown; restored from __doc__        """ x.__neg__() <==> -x """        pass    @staticmethod # known case of __new__    def __new__(S, *more): # real signature unknown; restored from __doc__        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """        pass    def __nonzero__(self): # real signature unknown; restored from __doc__        """ x.__nonzero__() <==> x != 0 """        pass    def __oct__(self): # real signature unknown; restored from __doc__        """ x.__oct__() <==> oct(x) """        pass    def __or__(self, y): # real signature unknown; restored from __doc__        """ x.__or__(y) <==> x|y """        pass    def __pos__(self): # real signature unknown; restored from __doc__        """ x.__pos__() <==> +x """        pass    def __pow__(self, y, z=None): # real signature unknown; restored from __doc__        """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """        pass    def __radd__(self, y): # real signature unknown; restored from __doc__        """ x.__radd__(y) <==> y+x """        pass    def __rand__(self, y): # real signature unknown; restored from __doc__        """ x.__rand__(y) <==> y&x """        pass    def __rdivmod__(self, y): # real signature unknown; restored from __doc__        """ x.__rdivmod__(y) <==> divmod(y, x) """        pass    def __rdiv__(self, y): # real signature unknown; restored from __doc__        """ x.__rdiv__(y) <==> y/x """        pass    def __repr__(self): # real signature unknown; restored from __doc__        """ x.__repr__() <==> repr(x) """        pass    def __rfloordiv__(self, y): # real signature unknown; restored from __doc__        """ x.__rfloordiv__(y) <==> y//x """        pass    def __rlshift__(self, y): # real signature unknown; restored from __doc__        """ x.__rlshift__(y) <==> y<<x """        pass    def __rmod__(self, y): # real signature unknown; restored from __doc__        """ x.__rmod__(y) <==> y%x """        pass    def __rmul__(self, y): # real signature unknown; restored from __doc__        """ x.__rmul__(y) <==> y*x """        pass    def __ror__(self, y): # real signature unknown; restored from __doc__        """ x.__ror__(y) <==> y|x """        pass    def __rpow__(self, x, z=None): # real signature unknown; restored from __doc__        """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """        pass    def __rrshift__(self, y): # real signature unknown; restored from __doc__        """ x.__rrshift__(y) <==> y>>x """        pass    def __rshift__(self, y): # real signature unknown; restored from __doc__        """ x.__rshift__(y) <==> x>>y """        pass    def __rsub__(self, y): # real signature unknown; restored from __doc__        """ x.__rsub__(y) <==> y-x """        pass    def __rtruediv__(self, y): # real signature unknown; restored from __doc__        """ x.__rtruediv__(y) <==> y/x """        pass    def __rxor__(self, y): # real signature unknown; restored from __doc__        """ x.__rxor__(y) <==> y^x """        pass    def __sizeof__(self, *args, **kwargs): # real signature unknown        """ Returns size in memory, in bytes """        pass    def __str__(self): # real signature unknown; restored from __doc__        """ x.__str__() <==> str(x) """        pass    def __sub__(self, y): # real signature unknown; restored from __doc__        """ x.__sub__(y) <==> x-y """        pass    def __truediv__(self, y): # real signature unknown; restored from __doc__        """ x.__truediv__(y) <==> x/y """        pass    def __trunc__(self, *args, **kwargs): # real signature unknown        """ Truncating an Integral returns itself. """        pass    def __xor__(self, y): # real signature unknown; restored from __doc__        """ x.__xor__(y) <==> x^y """        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"""long

三、浮点型

如：3.14159

每个浮点型都具备如下功能：

class float(object):    """    float(x) -> floating point number        Convert a string or number to a floating point number, if possible.    """    def as_integer_ratio(self):           """ 获取改值的最简比 """        """        float.as_integer_ratio() -> (int, int)        Return a pair of integers, whose ratio is exactly equal to the original        float and with a positive denominator.        Raise OverflowError on infinities and a ValueError on NaNs.        >>> (10.0).as_integer_ratio()        (10, 1)        >>> (0.0).as_integer_ratio()        (0, 1)        >>> (-.25).as_integer_ratio()        (-1, 4)        """        pass    def conjugate(self, *args, **kwargs): # real signature unknown        """ Return self, the complex conjugate of any float. """        pass    def fromhex(self, string):           """ 将十六进制字符串转换成浮点型 """        """        float.fromhex(string) -> float                Create a floating-point number from a hexadecimal string.        >>> float.fromhex(‘0x1.ffffp10‘)        2047.984375        >>> float.fromhex(‘-0x1p-1074‘)        -4.9406564584124654e-324        """        return 0.0    def hex(self):           """ 返回当前值的 16 进制表示 """        """        float.hex() -> string                Return a hexadecimal representation of a floating-point number.        >>> (-0.1).hex()        ‘-0x1.999999999999ap-4‘        >>> 3.14159.hex()        ‘0x1.921f9f01b866ep+1‘        """        return ""    def is_integer(self, *args, **kwargs): # real signature unknown        """ Return True if the float is an integer. """        pass    def __abs__(self):           """ x.__abs__() <==> abs(x) """        pass    def __add__(self, y):           """ x.__add__(y) <==> x+y """        pass    def __coerce__(self, y):           """ x.__coerce__(y) <==> coerce(x, y) """        pass    def __divmod__(self, y):           """ x.__divmod__(y) <==> divmod(x, y) """        pass    def __div__(self, y):           """ x.__div__(y) <==> x/y """        pass    def __eq__(self, y):           """ x.__eq__(y) <==> x==y """        pass    def __float__(self):           """ x.__float__() <==> float(x) """        pass    def __floordiv__(self, y):           """ x.__floordiv__(y) <==> x//y """        pass    def __format__(self, format_spec):           """        float.__format__(format_spec) -> string                Formats the float according to format_spec.        """        return ""    def __getattribute__(self, name):           """ x.__getattribute__(‘name‘) <==> x.name """        pass    def __getformat__(self, typestr):           """        float.__getformat__(typestr) -> string                You probably don‘t want to use this function.  It exists mainly to be        used in Python‘s test suite.                typestr must be ‘double‘ or ‘float‘.  This function returns whichever of        ‘unknown‘, ‘IEEE, big-endian‘ or ‘IEEE, little-endian‘ best describes the        format of floating point numbers used by the C type named by typestr.        """        return ""    def __getnewargs__(self, *args, **kwargs): # real signature unknown        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, x):           pass    def __int__(self):           """ x.__int__() <==> int(x) """        pass    def __le__(self, y):           """ x.__le__(y) <==> x<=y """        pass    def __long__(self):           """ x.__long__() <==> long(x) """        pass    def __lt__(self, y):           """ x.__lt__(y) <==> x<y """        pass    def __mod__(self, y):           """ x.__mod__(y) <==> x%y """        pass    def __mul__(self, y):           """ x.__mul__(y) <==> x*y """        pass    def __neg__(self):           """ x.__neg__() <==> -x """        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 __nonzero__(self):           """ x.__nonzero__() <==> x != 0 """        pass    def __pos__(self):           """ x.__pos__() <==> +x """        pass    def __pow__(self, y, z=None):           """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """        pass    def __radd__(self, y):           """ x.__radd__(y) <==> y+x """        pass    def __rdivmod__(self, y):           """ x.__rdivmod__(y) <==> divmod(y, x) """        pass    def __rdiv__(self, y):           """ x.__rdiv__(y) <==> y/x """        pass    def __repr__(self):           """ x.__repr__() <==> repr(x) """        pass    def __rfloordiv__(self, y):           """ x.__rfloordiv__(y) <==> y//x """        pass    def __rmod__(self, y):           """ x.__rmod__(y) <==> y%x """        pass    def __rmul__(self, y):           """ x.__rmul__(y) <==> y*x """        pass    def __rpow__(self, x, z=None):           """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """        pass    def __rsub__(self, y):           """ x.__rsub__(y) <==> y-x """        pass    def __rtruediv__(self, y):           """ x.__rtruediv__(y) <==> y/x """        pass    def __setformat__(self, typestr, fmt):           """        float.__setformat__(typestr, fmt) -> None                You probably don‘t want to use this function.  It exists mainly to be        used in Python‘s test suite.                typestr must be ‘double‘ or ‘float‘.  fmt must be one of ‘unknown‘,        ‘IEEE, big-endian‘ or ‘IEEE, little-endian‘, and in addition can only be        one of the latter two if it appears to match the underlying C reality.                Override the automatic determination of C-level floating point type.        This affects how floats are converted to and from binary strings.        """        pass    def __str__(self):           """ x.__str__() <==> str(x) """        pass    def __sub__(self, y):           """ x.__sub__(y) <==> x-y """        pass    def __truediv__(self, y):           """ x.__truediv__(y) <==> x/y """        pass    def __trunc__(self, *args, **kwargs): # real signature unknown        """ Return the Integral closest to x between 0 and x. """        pass    imag = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default    """the imaginary part of a complex number"""    real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default    """the real part of a complex number""" float

python不管表达式中有多少整形多少浮点型，只要存在浮点型，那么所有计算都按照浮点型计算，得出的结果也会是float类型

四、字符串

如：‘guojingjing‘

每个字符串都具备如下功能:

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) """        passstr

该类中常用的一些方法：

（1）capitalize()：将首字母大写

name=‘eric‘result=name.capitalize()print(result)
Eric

（2）center/ljust/rjst：固定字符串长度，居中/居左/居右 ，下面是使用示例，一般用在打印列表和字典的时候整理格式。　

name=‘eric‘result=name.center(20,‘*‘)print(result)********eric********

（3）count：子序列个数，用来统计一个字符串中包含指定子序列的个数。这个子序列可以是一个字符，也可以是多个字符

name=‘jfiagnngjaigngi‘result=name.count(‘d‘)print(result)0

name=‘jfiagnngjaigngi‘
result=name.count(‘n‘,0,10)#在0到10的位置去找
print(result)

2

（4）expandtabs：将tab转换成空格，默认一个tab转换成8个空格。当然这里也可以自行指定转换成多少个空格

name=‘alex‘result=name.expandtabs()print(len(result))4

（5）find：返回字符串中第一个子序列的下标。rfind：和find用法一样，只是它是从右向左查找index：和find的左右一致，只是find找不到的时候会返回-1，而index找不到的时候会报错，值得注意的是，当我们在一个字符串中查找某一个子序列的时候，如果这个字符串中含有多个子序列，只会返回第一个找到的下标，不会返回其他的。

name=‘alex‘result=name.find(‘x‘)#找到字符所在字符串中的位置print(result)3

（6）format：各种格式化，动态参数。

name=‘alex‘result=name.format(‘eric‘)print(result)alex

（7）endswith:是否以...（子串）结尾。这里的子串依然可以是一个或多个字符。

1 >>> str1 = ‘Alex‘2 >>> str1.endswith(‘x‘)3 True

(8)join用来做拼接

li=[‘a‘,‘l‘,‘e‘,‘x‘""]result="-".join(li)#用横杠将字符拼接起来print(result)a-l-e-x

（9）partition/split：这两个方法都用来分割。partition会将指定的子串提取并将子串两侧内容分割，只匹配一次，并返回元组；split会根据指定子串，将整个字符串所有匹配的子串匹配到并剔除，将其他内容分割，返回数组。

（10）replace：替换。会替换字符串中所有符合条件的子串。

1>>>name=‘alex is a man‘2>>>result=name.replace(‘a‘,‘o‘)3>>>print(result)olex is o mon

(11)swapcase：大写变小写，小写变大写

1>>>name=‘Alex is A man‘2>>>result=name.swapcase()3>>>print(result)aLEX IS a MAN

五、列表

如：[11,22,33]、[‘guojingjing‘, ‘huoweigang‘]

每个列表都具备如下功能：

class list(object):    """    list() -> new empty list    list(iterable) -> new list initialized from iterable‘s items    """    def append(self, p_object): # real signature unknown; restored from __doc__        """ L.append(object) -- append object to end """        pass    def count(self, value): # real signature unknown; restored from __doc__        """ L.count(value) -> integer -- return number of occurrences of value """        return 0    def extend(self, iterable): # real signature unknown; restored from __doc__        """ L.extend(iterable) -- extend list by appending elements from the iterable """        pass    def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__        """        L.index(value, [start, [stop]]) -> integer -- return first index of value.        Raises ValueError if the value is not present.        """        return 0    def insert(self, index, p_object): # real signature unknown; restored from __doc__        """ L.insert(index, object) -- insert object before index """        pass    def pop(self, index=None): # real signature unknown; restored from __doc__        """        L.pop([index]) -> item -- remove and return item at index (default last).        Raises IndexError if list is empty or index is out of range.        """        pass    def remove(self, value): # real signature unknown; restored from __doc__        """        L.remove(value) -- remove first occurrence of value.        Raises ValueError if the value is not present.        """        pass    def reverse(self): # real signature unknown; restored from __doc__        """ L.reverse() -- reverse *IN PLACE* """        pass    def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__        """        L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;        cmp(x, y) -> -1, 0, 1        """        pass    def __add__(self, y): # real signature unknown; restored from __doc__        """ x.__add__(y) <==> x+y """        pass    def __contains__(self, y): # real signature unknown; restored from __doc__        """ x.__contains__(y) <==> y in x """        pass    def __delitem__(self, y): # real signature unknown; restored from __doc__        """ x.__delitem__(y) <==> del x[y] """        pass    def __delslice__(self, i, j): # real signature unknown; restored from __doc__        """        x.__delslice__(i, j) <==> del x[i:j]                                      Use of negative indices is not supported.        """        pass    def __eq__(self, y): # real signature unknown; restored from __doc__        """ x.__eq__(y) <==> x==y """        pass    def __getattribute__(self, name): # real signature unknown; restored from __doc__        """ x.__getattribute__(‘name‘) <==> x.name """        pass    def __getitem__(self, y): # real signature unknown; restored from __doc__        """ x.__getitem__(y) <==> x[y] """        pass    def __getslice__(self, i, j): # real signature unknown; restored from __doc__        """        x.__getslice__(i, j) <==> x[i:j]                                      Use of negative indices is not supported.        """        pass    def __ge__(self, y): # real signature unknown; restored from __doc__        """ x.__ge__(y) <==> x>=y """        pass    def __gt__(self, y): # real signature unknown; restored from __doc__        """ x.__gt__(y) <==> x>y """        pass    def __iadd__(self, y): # real signature unknown; restored from __doc__        """ x.__iadd__(y) <==> x+=y """        pass    def __imul__(self, y): # real signature unknown; restored from __doc__        """ x.__imul__(y) <==> x*=y """        pass    def __init__(self, seq=()): # known special case of list.__init__        """        list() -> new empty list        list(iterable) -> new list initialized from iterable‘s items        # (copied from class doc)        """        pass    def __iter__(self): # real signature unknown; restored from __doc__        """ x.__iter__() <==> iter(x) """        pass    def __len__(self): # real signature unknown; restored from __doc__        """ x.__len__() <==> len(x) """        pass    def __le__(self, y): # real signature unknown; restored from __doc__        """ x.__le__(y) <==> x<=y """        pass    def __lt__(self, y): # real signature unknown; restored from __doc__        """ x.__lt__(y) <==> x<y """        pass    def __mul__(self, n): # real signature unknown; restored from __doc__        """ x.__mul__(n) <==> x*n """        pass    @staticmethod # known case of __new__    def __new__(S, *more): # real signature unknown; restored from __doc__        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """        pass    def __ne__(self, y): # real signature unknown; restored from __doc__        """ x.__ne__(y) <==> x!=y """        pass    def __repr__(self): # real signature unknown; restored from __doc__        """ x.__repr__() <==> repr(x) """        pass    def __reversed__(self): # real signature unknown; restored from __doc__        """ L.__reversed__() -- return a reverse iterator over the list """        pass    def __rmul__(self, n): # real signature unknown; restored from __doc__        """ x.__rmul__(n) <==> n*x """        pass    def __setitem__(self, i, y): # real signature unknown; restored from __doc__        """ x.__setitem__(i, y) <==> x[i]=y """        pass    def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__        """        x.__setslice__(i, j, y) <==> x[i:j]=y                                      Use  of negative indices is not supported.        """        pass    def __sizeof__(self): # real signature unknown; restored from __doc__        """ L.__sizeof__() -- size of L in memory, in bytes """        pass    __hash__ = Nonelist

append()往列表的尾部再加一个

copy()以后会将深拷贝和浅拷贝，这里的拷贝叫浅拷贝

列表里的元素可以是字符串，列表，

Count()判断里面某个元素出现的次数

extend()把一个列表和一个元组合并

1>>>li=list((1,2,3,))2>>>print(li)3>>>li.extend([11,22])4>>>print(li)[1, 2, 3][1, 2, 3, 11, 22]

Python学习第二天