一、语法参考
help() 函数的语法格式如下：
参数说明：
- request：可选参数，要查看其帮助信息的对象，如类、函数、模块、数据类型等；
- 返回值：返回对象的帮助信息。
二、示例
【示例1】查看input()函数的帮助信息。利用help()函数查看input()函数的帮助信息，示例代码如下：
help(input) # 查看input()函数的信息
输出结果为：
Help on built-in function input in module builtins:
input(prompt='', /)
Read a string from standard input. The trailing newline is stripped.
The prompt string, if given, is printed to standard output without a
trailing newline before reading input.
If the user hits EOF (*nix: Ctrl-D, Windows: Ctrl-Z+Return), raise EOFError.
On *nix systems, readline is used if available.
【示例2】查看Python中所有的保留字。利用help()函数查看Python中所有的保留字，示例代码如下：
help('keywords') # 查看所有的关键字
输出结果为：
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
【示例3】启动帮助系统。使用help()函数启动帮助系统，查看对象的帮助信息，示例代码如下：
help() # 调用help()函数，不传入参数
输出结果如下图所示：
如果 help() 函数不传入参数，则会在解释器控制台启动帮助系统，如上图所示；在帮助系统内部输入模块名、类名、函数名、关键字等，会在控制台上显示其使用说明，输入 quit，将退出帮助系统。在 help> 后输入 keywords，Python 中所有的关键字将会显示在控制台。
【示例4】查看os模块的帮助信息。使用help()函数查看os模块的帮助信息，示例代码如下：
help('os') # 查看os模块的帮助信息
【示例5】查看模块中指定函数的帮助信息。使用help()函数查看os.path模块中 "abspath" 函数的帮助信息，示例代码如下：
help("os.path.abspath") # 查看os.path模块中"abspath"函数的帮助信息
输出结果为：
Help on function abspath in os.path:
os.path.abspath = abspath(path)
Return the absolute version of a path.
【示例6】看数据类型的帮助信息。使用help()函数查看字符类型的帮助信息，示例代码如下：
help('str') # 查看str数据类型的帮助
输出结果为：
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:
........
【示例7】查看关键字的帮助信息。使用help()函数查看关键字 "if" 的帮助信息，示例代码如下：
help("if") # 查看if保留字的帮助信息
输出结果为：
The "if" statement
******************
The "if" statement is used for conditional execution:
if_stmt ::= "if" assignment_expression ":" suite
("elif" assignment_expression ":" suite)*
["else" ":" suite]
It selects exactly one of the suites by evaluating the expressions one
by one until one is found to be true (see section Boolean operations
for the definition of true and false); then that suite is executed
(and no other part of the "if" statement is executed or evaluated).
If all expressions are false, the suite of the "else" clause, if
present, is executed.
Related help topics: TRUTHVALUE
【示例8】查看错误异常的帮助信息。使用help()函数查看语法错误异常 "SyntaxError" 的帮助信息，示例代码如下：
help("SyntaxError") # 查看语法错误"SyntaxError"的帮助信息
输出结果为：
Help on class SyntaxError in module builtins:
class SyntaxError(Exception)
| Invalid syntax.
|
| Method resolution order:
| SyntaxError
| Exception
| BaseException
| object
|
| Built-in subclasses:
| IndentationError
|
| Methods defined here:
|
| __init__(self, /, *args, **kwargs)
| Initialize self. See help(type(self)) for accurate signature.
|
| __str__(self, /)
| Return str(self).
........
【示例9】查看数据类型中某个方法的帮助信息。使用help()函数查看字符类型中 "find" 方法的帮助信息，示例代码如下：
help("str.find") # 查看字符类型中的"find"方法的帮助信息
输出结果为：
Help on method_descriptor in str:
str.find = find(...) unbound builtins.str method
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.
【示例10】 查看所有的模块。使用help()函数查看当前python中的所有模块，示例代码如下：
help('modules') # 查看当前python中所有的模块
输出结果为：
Please wait a moment while I gather a list of all available modules...
Crypto automat hyperlink reprlib
DataRecorder backend_interagg idlelib requests
Django5Study base64 idna requests_file
DownloadKit bdb imaplib retrying
DrissionPage binascii imghdr rlcompleter
IPython bisect importlib run
OpenSSL blinker importlib_metadata runpy
PIL bs4 incremental sched
.........
【示例11】查看Python中提供的帮助主题的列表。使用help()函数查看Python中提供的帮助主题的列表，示例代码如下：
help("topics") # 查看Python中提供的帮助主题的列表
输出结果为：
Here is a list of available topics. Enter any topic name to get more help.
ASSERTION DELETION LOOPING SHIFTING
ASSIGNMENT DICTIONARIES MAPPINGMETHODS SLICINGS
ATTRIBUTEMETHODS DICTIONARYLITERALS MAPPINGS SPECIALATTRIBUTES
ATTRIBUTES DYNAMICFEATURES METHODS SPECIALIDENTIFIERS
AUGMENTEDASSIGNMENT ELLIPSIS MODULES SPECIALMETHODS
BASICMETHODS EXCEPTIONS NAMESPACES STRINGMETHODS
BINARY EXECUTION NONE STRINGS
BITWISE EXPRESSIONS NUMBERMETHODS SUBSCRIPTS
BOOLEAN FLOAT NUMBERS TRACEBACKS
CALLABLEMETHODS FORMATTING OBJECTS TRUTHVALUE
CALLS FRAMEOBJECTS OPERATORS TUPLELITERALS
CLASSES FRAMES PACKAGES TUPLES
CODEOBJECTS FUNCTIONS POWER TYPEOBJECTS
COMPARISON IDENTIFIERS PRECEDENCE TYPES
COMPLEX IMPORTING PRIVATENAMES UNARY
CONDITIONAL INTEGER RETURNING UNICODE
CONTEXTMANAGERS LISTLITERALS SCOPING
CONVERSIONS LISTS SEQUENCEMETHODS
DEBUGGING LITERALS SEQUENCES
【示例12】查看python某一个主题的帮助文档的内容。使用help()函数查看python某一个主题的帮助文档的内容，示例代码如下：
help("UNICODE") # 查看python某一个主题的帮助文档的内容
输出结果为：
String and Bytes literals
*************************
String literals are described by the following lexical definitions:
stringliteral ::= [stringprefix](shortstring | longstring)
stringprefix ::= "r" | "u" | "R" | "U" | "f" | "F"
| "fr" | "Fr" | "fR" | "FR" | "rf" | "rF" | "Rf" | "RF"
shortstring ::= "'" shortstringitem* "'" | '"' shortstringitem* '"'
longstring ::= "'''" longstringitem* "'''" | '"""' longstringitem* '"""'
shortstringitem ::= shortstringchar | stringescapeseq
longstringitem ::= longstringchar | stringescapeseq
shortstringchar ::= <any source character except "\" or newline or the quote>
longstringchar ::= <any source character except "\">
stringescapeseq ::= "\" <any source character>
bytesliteral ::= bytesprefix(shortbytes | longbytes)
bytesprefix ::= "b" | "B" | "br" | "Br" | "bR" | "BR" | "rb" | "rB" | "Rb" | "RB"
shortbytes ::= "'" shortbytesitem* "'" | '"' shortbytesitem* '"'
longbytes ::= "'''" longbytesitem* "'''" | '"""' longbytesitem* '"""'
shortbytesitem ::= shortbyteschar | bytesescapeseq
longbytesitem ::= longbyteschar | bytesescapeseq
shortbyteschar ::= <any ASCII character except "\" or newline or the quote>
longbyteschar ::= <any ASCII character except "\">
bytesescapeseq ::= "\" <any ASCII character>
..........