python 3中的意外打印输出

Question

I'm doing a python 3 tutorial and i'm trying to figure out where in my output these parentheses are coming from.

students = int (input())
total = dict()
for i in range(0,students):
  tokens = input().split()
  name = tokens[0]
  total[name] = float(tokens[1]) + float(tokens[2]) + float(tokens[3])

student = input(())
print ("{0:.2f}".format(total[student] / 3))

Expected Output

56.00

My Output

()56.00

Answer 1

replace this:

student = input(())

with:

student = input()

This is what happening :

 >>> student = input(())
()

Answer 2

In student = input(()) you are passing an empty tuple as the prompt argument to the input function. Normally, you pass input a prompt string , however input (and raw_input in Python 2) will happily accept any object for the prompt and convert it to a string, just like print does. If no prompt is supplied then no prompt gets printed. (I suspect that input simply passes the prompt to print ).

So your unexpected () is simply that empty tuple, converted to a string.