python自带help功能怎么使用

python help使用

C:\Users\wusong>python
Python 3.8.2rc1 (tags/v3.8.2rc1:8623e68, Feb 11 2020, 10:46:21) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>

输入help()

>>> help
Type help() for interactive help, or help(object) for help about object.
>>> help()
Welcome to Python 3.8's help utility!
If this is your first time using Python, you should definitely check out
the tutorial on the Internet at https://docs.python.org/3.8/tutorial/.
Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules.  To quit this help utility and
return to the interpreter, just type "quit".
To get a list of available modules, keywords, symbols, or topics, type
"modules", "keywords", "symbols", or "topics".  Each module also comes
with a one-line summary of what it does; to list the modules whose name
or summary contain a given string such as "spam", type "modules spam".
help>

这句话：To get a list of available modules, keywords, symbols, or topics, type "modules", "keywords", "symbols", or "topics".

意思就是：

要获取可用模块、关键字、符号或主题的列表，请键入 “模块”、“关键字”、“符号”或“主题”。

modules

我们先看下modules

在help模式下输入：modules

help> modules
Please wait a moment while I gather a list of all available modules...
D:\software_install\python\lib\pkgutil.py:92: UserWarning: The numpy.array_api submodule is still experimental. See NEP 47.
  __import__(info.name)
PIL                 asyncpg             idna                selenium
PyInstaller         atexit              imaplib             serial
PyQt5               atlastk             imghdr              setuptools
__future__          attr                imp                 shelve
_abc                attrs               importlib           shlex
_ast                audioop             inspect             shutil
_asyncio            backports           io                  signal
_bisect             base64              ipaddress           simplejson
_blake2             bcrypt              itertools           site
_bootlocale         bdb                 jinja2              six
_bz2                billiard            json                smtpd
_cffi_backend       binascii            keyword             smtplib
_codecs             binhex              kiwisolver          sndhdr
_codecs_cn          bisect              kombu               sniffio
_codecs_hk          broadcaster         lib2to3             socket
_codecs_iso2022     builtins            libfuturize         socketserver
_codecs_jp          bz2                 libpasteurize       socks
_codecs_kr          cProfile            linecache           sockshandler
_codecs_tw          calendar            locale              sortedcontainers
_collections        celery              logging             sqlalchemy
_collections_abc    certifi             loguru              sqlite3
_compat_pickle      cffi                lzma                sqlparse
_compression        cgi                 mailbox             sre_compile
_contextvars        cgitb               mailcap             sre_constants
_csv                charset_normalizer  markupsafe          sre_parse
_ctypes             chunk               marshal             ssl
_ctypes_test        click               math                starlette
_datetime           click_didyoumean    matplotlib          stat
_decimal            click_plugins       mimetypes           statistics
_dummy_thread       click_repl          mmap                string
_elementtree        cmath               modulefinder        stringprep
_functools          cmd                 msilib              struct
_hashlib            code                msvcrt              subprocess
_heapq              codecs              multiprocessing     sunau
_imp                codeop              nacl                symbol
_io                 collections         netrc               symtable
_json               colorama            nntplib             sys
_locale             colorsys            nt                  sysconfig
_lsprof             compileall          ntpath              tabnanny
_lzma               concurrent          nturl2path          tarfile
_markupbase         configparser        numbers             telnetlib
_md5                contextlib          numpy               tempfile
_msi                contextvars         opcode              test
_multibytecodec     contourpy           operator            textwrap
_multiprocessing    copy                optparse            tftpy
_opcode             copyreg             ordered_set         this
_operator           crypt               ordlookup           threading
_osx_support        cryptography        os                  time
_overlapped         csv                 outcome             timeit
_pickle             ctypes              packaging           tkinter
_py_abc             curses              paramiko            token
_pydecimal          cv2                 parser              tokenize
_pyinstaller_hooks_contrib cycler              past                tortoise
_pyio               databases           pathlib             trace
_queue              dataclasses         pdb                 traceback
_random             datetime            pefile              tracemalloc
_ruamel_yaml        dateutil            peutils             trio
_sha1               dbm                 pickle              trio_websocket
_sha256             decimal             pickletools         tty
_sha3               deepdiff            pip                 turtle
_sha512             difflib             pipes               turtledemo
_signal             dis                 pkg_resources       types
_sitebuiltins       distlib             pkgutil             typing
_socket             distutils           platform            typing_extensions
_sqlite3            django              platformdirs        tzdata
_sre                doctest             plistlib            unicodedata
_ssl                dotenv              poplib              unittest
_stat               dummy_threading     posixpath           urllib
_statistics         easy_install        pprint              urllib3
_string             email               prettytable         uu
_strptime           encodings           profile             uuid
_struct             ensurepip           prompt_toolkit      uvicorn
_symtable           enum                pstats              venv
_testbuffer         errno               psutil              vine
_testcapi           fastapi             pty                 virtualenv
_testconsole        faulthandler        py_compile          warnings
_testimportmultiple filecmp             pyclbr              watchfiles
_testmultiphase     fileinput           pycparser           wave
_thread             filelock            pydantic            wcwidth
_threading_local    fnmatch             pydoc               weakref
_tkinter            fontTools           pydoc_data          webbrowser
_tracemalloc        formatter           pyecharts           websockets
_warnings           fractions           pyexpat             win32_setctime
_weakref            ftplib              pylab               win32ctypes
_weakrefset         functools           pyparsing           winreg
_winapi             future              pyqt5_plugins       winsound
_xxsubinterpreters  gc                  pyqt5_tools         wsgiref
_yaml               genericpath         pytz                wsproto
abc                 getopt              qt5_applications    xdrlib
aifc                getpass             qt5_tools           xlrd
altgraph            gettext             queue               xlwt
amqp                glob                quopri              xml
antigravity         greenlet            random              xmlrpc
anyio               gzip                re                  xxsubtype
argparse            h21                 reprlib             yaml
array               hashlib             requests            zipapp
asgiref             heapq               rlcompleter         zipfile
ast                 hmac                runpy               zipimport
async_generator     html                sched               zlib
asynchat            http                secrets
asyncio             httptools           select
asyncore            idlelib             selectors
Enter any module name to get more help.  Or, type "modules spam" to search
for modules whose name or summary contain the string "spam".
help>

从这里可以看出还是有相当多的模块，比如我们常用的re,xlrd当然也有我们后期安装的；挑一个进去看看，有啥风景，就挑xlrd

help> xlrd
Help on package xlrd:
NAME
    xlrd
DESCRIPTION
    # Copyright (c) 2005-2012 Stephen John Machin, Lingfo Pty Ltd
    # This module is part of the xlrd package, which is released under a
    # BSD-style licence.
PACKAGE CONTENTS
    biffh
    book
    compdoc
    formatting
    formula
    info
    sheet
    timemachine
    xldate
FUNCTIONS
    count_records(filename, outfile=)
        For debugging and analysis: summarise the file's BIFF records.
        ie: produce a sorted file of ``(record_name, count)``.
        :param filename: The path to the file to be summarised.
        :param outfile: An open file, to which the summary is written.
-- More  -- 行数:

这里面会详细介绍xlrd模块的名字，描述，模块目录、功能、版本、文件位置等信息，在最后一行看到-- More -- ，这是一个分页符，表示当前页面不能全部显示所有信息，需要部分分页操作，可以使用空格键切换下一页，也可以使用回车键看下一行，看你自己的需求进行操作，如果不想看了可输入q退出阅读模式，进入help模式，再输入q则可以继续退出help模式；

help> q
You are now leaving help and returning to the Python interpreter.
If you want to ask for help on a particular object directly from the
interpreter, you can type "help(object)".  Executing "help('string')"
has the same effect as typing a particular string at the help> prompt.
>>>

keywords

再看下我们后面会常说的关键字

help> keywords
Here is a list of the Python keywords.  Enter any keyword to get more help.
False               class               from                or
None                continue            global              pass
True                def                 if                  raise
and                 del                 import              return
as                  elif                in                  try
assert              else                is                  while
async               except              lambda              with
await               finally             nonlocal            yield
break               for                 not

symbols

这个是罗列了我们在python语言中涉及的运算符

help> symbols
Here is a list of the punctuation symbols which Python assigns special meaning
to. Enter any symbol to get more help.
!=                  +                   <=                  __
"                   +=                  <>                  `
"""                 ,                   ==                  b"
%                   -                   >                   b'
%=                  -=                  >=                  f"
&                   .                   >>                  f'
&=                  ...                 >>=                 j
'                   /                   @                   r"
'''                 //                  J                   r'
(                   //=                 [                   u"
)                   /=                  \                   u'
*                   :                   ]                   |
**                  <                   ^                   |=
**=                 <<                  ^=                  ~
*=                  <<=                 _