Python help函数

Posted 2021-03-03 shuopython

python 3.x版本虽然比2.x少了一些内置函数，但是 python 内置 函数没有60个，也有40个，那么多内置函数你记得过来吗？为了方便使用，python 提供了help函数专门用来提供查看函数或模块用途的详细说明；

 

一.help函数简介

语法如下：

help([object])

 

参数：

object – 对象/函数名/模块；

返回值 – 返回对象的帮助信息；

 

 

二.help函数使用

1.查看内置函数的帮助信息

 

print(help(type)) # 内置函数type  - 获取数据变量类型

 

 

 

输出结果：

Help on class type in module builtins:
 
class type(object)
|  type(object_or_name, bases, dict)
|  type(object) -> the object‘s type
|  type(name, bases, dict) -> a new type
|  
|  Methods defined here:
|  
|  __call__(self, /, *args, **kwargs)
|      Call self as a function.
|  
|  __delattr__(self, name, /)
|      Implement delattr(self, name).
|  
|  __dir__(...)
|      __dir__() -> list
|      specialized __dir__ implementation for types
|  
|  __getattribute__(self, name, /)
|      Return getattr(self, name).
|  
|  __init__(self, /, *args, **kwargs)
|      Initialize self.  See help(type(self)) for accurate signature.
|  
|  __instancecheck__(...)
|      __instancecheck__() -> bool
|      check if an object is an instance
|  
|  __new__(*args, **kwargs)
|      Create and return a new object.  See help(type) for accurate signature.
|  
|  __prepare__(...)
|      __prepare__() -> dict
|      used to create the namespace for the class statement
|  
|  __repr__(self, /)
|      Return repr(self).
|  
|  __setattr__(self, name, value, /)
|      Implement setattr(self, name, value).
|  
|  __sizeof__(...)
|      __sizeof__() -> int
|      return memory consumption of the type object
|  
|  __subclasscheck__(...)
|      __subclasscheck__() -> bool
|      check if a class is a subclass
|  
|  __subclasses__(...)
|      __subclasses__() -> list of immediate subclasses
|  
|  mro(...)
|      mro() -> list
|      return a type‘s method resolution order
|  
|  ----------------------------------------------------------------------
|  Data descriptors defined here:
|  
|  __abstractmethods__
|  
|  __dict__
|  
|  __text_signature__
|  
|  ----------------------------------------------------------------------
|  Data and other attributes defined here:
|  
|  __base__ = <class ‘object‘>
|      The most base type
|  
|  __bases__ = (<class ‘object‘>,)
|  
|  __basicsize__ = 864
|  
|  __dictoffset__ = 264
|  
|  __flags__ = -2146675712
|  
|  __itemsize__ = 40
|  
|  __mro__ = (<class ‘type‘>, <class ‘object‘>)
|  
|  __weakrefoffset__ = 368
 
None
 
Process finished with exit code 0

 

 

 

 

2.查看数据类型的帮助信息

 

# !usr/bin/env python
# -*- coding:utf-8 _*-
"""
@Author:何以解忧
@Blog(个人博客地址): shuopython.com
@WeChat Official Account(微信公众号)：猿说编程
@Github:www.github.com
 
@File:python_help.py
@Time:2020/03/20 09:35
 
@Motto:不积跬步无以至千里，不积小流无以成江海，程序人生的精彩需要坚持不懈地积累！
"""
 
 
print(help(str))  # 内置数据变量类型 - 字符

 

 

 

输出结果：

 

Help on class str in module builtins:
 
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‘.
|  
|  Methods defined here:
|  
|  __add__(self, value, /)
|      Return self+value.
|  
|  __contains__(self, key, /)
|      Return key in self.
|  
|  __eq__(self, value, /)
|      Return self==value.
|  
|  __format__(...)
|      S.__format__(format_spec) -> str
|      
|      Return a formatted version of S as described by format_spec.
|  
|  __ge__(self, value, /)
|      Return self>=value.
|  
|  __getattribute__(self, name, /)
|      Return getattr(self, name).
|  
|  __getitem__(self, key, /)
|      Return self[key].
|  
|  __getnewargs__(...)
|  
|  __gt__(self, value, /)
|      Return self>value.
|  
|  __hash__(self, /)
|      Return hash(self).
|  
|  __iter__(self, /)
|      Implement iter(self).
|  
|  __le__(self, value, /)
|      Return self<=value.
|  
|  __len__(self, /)
|      Return len(self).
|  
|  __lt__(self, value, /)
|      Return self<value.
|  
|  __mod__(self, value, /)
|      Return self%value.
|  
|  __mul__(self, value, /)
|      Return self*value.n
|  
|  __ne__(self, value, /)
|      Return self!=value.
|  
|  __new__(*args, **kwargs) from builtins.type
|      Create and return a new object.  See help(type) for accurate signature.
|  
|  __repr__(self, /)
|      Return repr(self).
|  
|  __rmod__(self, value, /)
|      Return value%self.
|  
|  __rmul__(self, value, /)
|      Return self*value.
|  
|  __sizeof__(...)
|      S.__sizeof__() -> size of S in memory, in bytes
|  
|  __str__(self, /)
|      Return str(self).
|  
|  capitalize(...)
|      S.capitalize() -> str
|      
|      Return a capitalized version of S, i.e. make the first character
|      have upper case and the rest lower case.
|  
|  casefold(...)
|      S.casefold() -> str
|      
|      Return a version of S suitable for caseless comparisons.
|  
|  center(...)
|      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)
|  
|  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.
|  
|  encode(...)
|      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.
|  
|  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=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.
|  
|  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) -> str
|      
|      Return a formatted version of S, using substitutions from args and kwargs.
|      The substitutions are identified by braces (‘{‘ and ‘}‘).
|  
|  format_map(...)
|      S.format_map(mapping) -> str
|      
|      Return a formatted version of S, using substitutions from mapping.
|      The substitutions are identified by braces (‘{‘ and ‘}‘).
|  
|  index(...)
|      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.
|  
|  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.
|  
|  isdecimal(...)
|      S.isdecimal() -> bool
|      
|      Return True if there are only decimal characters 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.
|  
|  isidentifier(...)
|      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".
|  
|  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.
|  
|  isnumeric(...)
|      S.isnumeric() -> bool
|      
|      Return True if there are only numeric characters in S,
|      False otherwise.
|  
|  isprintable(...)
|      S.isprintable() -> bool
|      
|      Return True if all characters in S are considered
|      printable in repr() or S is empty, 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. upper- and titlecase 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) -> str
|      
|      Return a string which is the concatenation of the strings in the
|      iterable.  The separator between elements is S.
|  
|  ljust(...)
|      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).
|  
|  lower(...)
|      S.lower() -> str
|      
|      Return a copy of the string S converted to lowercase.
|  
|  lstrip(...)
|      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.
|  
|  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]) -> 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.
|  
|  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
|      
|      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.
|  
|  rjust(...)
|      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).
|  
|  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=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.
|  
|  rstrip(...)
|      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.
|  
|  split(...)
|      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.
|  
|  splitlines(...)
|      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.
|  
|  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]) -> 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.
|  
|  swapcase(...)
|      S.swapcase() -> str
|      
|      Return a copy of S with uppercase characters converted to lowercase
|      and vice versa.
|  
|  title(...)
|      S.title() -> str
|      
|      Return a titlecased version of S, i.e. words start with title case
|      characters, all remaining cased characters have lower case.
|  
|  translate(...)
|      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.
|  
|  upper(...)
|      S.upper() -> str
|      
|      Return a copy of S converted to uppercase.
|  
|  zfill(...)
|      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.
|  
|  ----------------------------------------------------------------------
|  Static methods defined here:
|  
|  maketrans(x, y=None, z=None, /)
|      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.
 
None
-10
 
Process finished with exit code 0

 

 

 

 

 

 

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