在Python中print（）[]的含义是什么？

Question

While browsing codegolf, I found this :

g=input();print("Approved","Summer School","Failed")[(g<7)+(g<3)]

I don't understand what the [] means after print()... Any clarification ?

Answer 1

>>> print("Approved","Summer School","Failed")[0]
Approved
>>> print("Approved","Summer School","Failed")[1]
Summer School
>>> print("Approved","Summer School","Failed")[2]
Failed

See the pattern? It's just simple indexing.

By the way we always know (g<7)+(g<3) will be >= 0 ( False + False ) and <= 2 ( True + True ).

Recall that bool is a subclass of int , and that True == 1 and False == 0 (which is why we can add bool s, as is done above).

Finally, it goes without saying that this confusion could have easily been avoided with an extra set of parenthesis:

print(("Approved","Summer School","Failed")[(g<7)+(g<3)])

Answer 2

It's just tuple indexing. No different from this:

x = (1, 2, 3)[1]

which assigns 2 to x .

In your more complex variant, an element of the tuple is selected and then passed to print .

The confusion is that the code makes it look like you are calling a function named print . This confusion was removed in Python 3 by dint of print being turned into a function. The code in your question does something utterly different in Python 3.

Answer 3

print(x,y,...)[i] should be parsed as print (x,y)[i] . Its just print followed by tuple .