Python help函数

python 3.x版本虽然比2.x少了一些内置函数，但是函数没有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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