*和**的用法，用作实参：Unpacking Argument Lists

本文介绍了Python中如何使用*及**运算符来解包列表、元组和字典，以便为函数提供单独的位置参数和关键字参数。通过示例展示了如何利用这些特性简化代码。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

The reverse situation occurs when the arguments are already in a list or tuple but need to be unpacked for a function call requiring separate positional arguments. For instance, the built-in range() function expects separate start and stop arguments. If they are not available separately, write the function call with the *-operator to unpack the arguments out of a list or tuple:

  >>> 
  >>> list(range(3, 6))            # normal call with separate arguments
[3, 4, 5]
>>> args = [3, 6]
>>> list(range(*args))            # 等价于range（3,6）call with arguments unpacked from a list
[3, 4, 5]			
 
 

In the same fashion, dictionaries can deliver keyword arguments with the **-operator:

  >>> 
  >>> def parrot(voltage, state='a stiff', action='voom'):
...     print("-- This parrot wouldn't", action, end=' ')
...     print("if you put", voltage, "volts through it.", end=' ')
...     print("E's", state, "!")
...
>>> d = {"voltage": "four million", "state": "bleedin' demised", "action": "VOOM"}
>>> parrot(**d)		# 等价于parrot（voltage = 'four million', state = 'bleedin demised', action = 'voom'） 
  
-- This parrot wouldn't VOOM if you put four million volts through it. E's bleedin' demised !  
 