help()

功能：用于查看函数或模块用途的详细说明。
参数：一个对象

实例

print(help('keyword'))
print(help(list))
print(help(list.append))

输出

Help on module keyword:
NAME
    keyword - Keywords (from "graminit.c")
DESCRIPTION
    This file is automatically generated; please don't muck it up!
    To update the symbols in this file, 'cd' to the top directory of
    the python source tree after building the interpreter and run:
        ./python Lib/keyword.py
FUNCTIONS
    iskeyword = __contains__(...) method of builtins.frozenset instance
        x.__contains__(y) <==> y in x.
DATA
    __all__ = ['iskeyword', 'kwlist']
    kwlist = ['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'aw...
FILE
    d:\python\pythoninstall\lib\keyword.py
None
Help on class list in module builtins:
class list(object)
 |  list(iterable=(), /)
 |  
 |  Built-in mutable sequence.
 |  
 |  If no argument is given, the constructor creates a new empty list.
 |  The argument must be an iterable if specified.
 |  
 |  Methods defined here:
 |  
 |  __add__(self, value, /)
 |      Return self+value.
 |  
 |  __contains__(self, key, /)
 |      Return key in self.
 |  
 |  __delitem__(self, key, /)
 |      Delete self[key].
 |  
 |  __eq__(self, value, /)
 |      Return self==value.
 |  
 |  __ge__(self, value, /)
 |      Return self>=value.
 |  
 |  __getattribute__(self, name, /)
 |      Return getattr(self, name).
 |  
 |  __getitem__(...)
 |      x.__getitem__(y) <==> x[y]
 |  
 |  __gt__(self, value, /)
 |      Return self>value.
 |  
 |  __iadd__(self, value, /)
 |      Implement self+=value.
 |  
 |  __imul__(self, value, /)
 |      Implement self*=value.
 |  
 |  __init__(self, /, *args, **kwargs)
 |      Initialize self.  See help(type(self)) for accurate signature.
 |  
 |  __iter__(self, /)
 |      Implement iter(self).
 |  
 |  __le__(self, value, /)
 |      Return self<=value.
 |  
 |  __len__(self, /)
 |      Return len(self).
 |  
 |  __lt__(self, value, /)
 |      Return self<value.
 |  
 |  __mul__(self, value, /)
 |      Return self*value.
 |  
 |  __ne__(self, value, /)
 |      Return self!=value.
 |  
 |  __repr__(self, /)
 |      Return repr(self).
 |  
 |  __reversed__(self, /)
 |      Return a reverse iterator over the list.
 |  
 |  __rmul__(self, value, /)
 |      Return value*self.
 |  
 |  __setitem__(self, key, value, /)
 |      Set self[key] to value.
 |  
 |  __sizeof__(self, /)
 |      Return the size of the list in memory, in bytes.
 |  
 |  append(self, object, /)
 |      Append object to the end of the list.
 |  
 |  clear(self, /)
 |      Remove all items from list.
 |  
 |  copy(self, /)
 |      Return a shallow copy of the list.
 |  
 |  count(self, value, /)
 |      Return number of occurrences of value.
 |  
 |  extend(self, iterable, /)
 |      Extend list by appending elements from the iterable.
 |  
 |  index(self, value, start=0, stop=9223372036854775807, /)
 |      Return first index of value.
 |      
 |      Raises ValueError if the value is not present.
 |  
 |  insert(self, index, object, /)
 |      Insert object before index.
 |  
 |  pop(self, index=-1, /)
 |      Remove and return item at index (default last).
 |      
 |      Raises IndexError if list is empty or index is out of range.
 |  
 |  remove(self, value, /)
 |      Remove first occurrence of value.
 |      
 |      Raises ValueError if the value is not present.
 |  
 |  reverse(self, /)
 |      Reverse *IN PLACE*.
 |  
 |  sort(self, /, *, key=None, reverse=False)
 |      Stable sort *IN PLACE*.
 |  
 |  ----------------------------------------------------------------------
 |  Static methods defined here:
 |  
 |  __new__(*args, **kwargs) from builtins.type
 |      Create and return a new object.  See help(type) for accurate signature.
 |  
 |  ----------------------------------------------------------------------
 |  Data and other attributes defined here:
 |  
 |  __hash__ = None
None
Help on method_descriptor:
append(self, object, /)
    Append object to the end of the list.
None

id()

功能：用于获取对象的内存地址。
参数：一个对象

实例

a = 4
b = 4
c = [1, 2]
d = [1, 2]
e = (1, 2)
f = 5
print(id(a))
print(id(b))
print(id(f))
print(id(c))
print(id(d))
print(id(e))
print(id(d[0]))
print(id(d[1]))

输出

140725131924608
140725131924608
140725131924640
2708472488520
2708472488584
2708472974984
140725131924512
140725131924544

dir()

功能：函数不带参数时，返回当前范围内的变量、方法和定义的类型列表；带参数时，返回参数的属性、方法列表。
如果参数包含方法__dir__()，该方法将被调用。如果参数不包含__dir__()，该方法将最大限度地收集参数信息。
参数：对象、变量、类型。

实例

import keyword
print(dir())
print(dir(keyword))

输出

['__annotations__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', 
'__spec__', 'keyword']
['__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 
'iskeyword', 'kwlist', 'main']