问题
Assume line is: "Chicago Sun 01:52".
What does *a, b, c = line.split() do? In particular, what is the significance of the asterisk?
Edit: Upon testing it, it seems like "Chicago", "Sun" and "01:52" are all stored in a, b and c. The asterisk seems to lead to "Chicago" being stored in a as the first element of a list. So, we have a = ["Chicago"], b = "Sun" and c = "01:52". Could anyone point to material on the functionality of the asterisk operator in this situation?
回答1:
Splitting that text by whitespace will give you:
In [743]: line.split()
Out[743]: ['Chicago', 'Sun', '01:52']
Now, this is a 3 element list. The assignment will take the last two elements of the output and assign them to b and c respectively. The *, or the splat operator will then pass the remainder of that list to a, and so a is a list of elements. In this case, a is a single-element list.
In [744]: *a, b, c = line.split()
In [745]: a
Out[745]: ['Chicago']
In [746]: b
Out[746]: 'Sun'
In [747]: c
Out[747]: '01:52'
Look at PEP 3132 and Where are python's splat operators * and ** valid? for more information on the splat operators, how they work and where they're applicable.
来源：https://stackoverflow.com/questions/45870330/what-does-the-asterisk-do-in-a-b-c-line-split