相当于Python 2中心的Python 3

Question

The following Works in Python 2

print ("|").center(11,'-')

When I try the same code in Python 3 I get the following error Message:

AttributeError: 'NoneType' object has no attribute 'center'

How would one do the same thing in Python 3?

Answer 1

>>> print("|".center(11, '-'))
-----|-----

In Python 3 print is a function so you need to do the centering inside - otherwise you'd call it on the return value of print .

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Additionally, in Python 2 you should not put parentheses there at all:

>>> print "|".center(11, '-')
-----|-----

The reason why it works with parentheses is that (foo) and foo are the same thing.

Another option to make it work in both Python 2 and Python 3 would be to add from __future__ import print_function to the top of your file and then use the Python 3 syntax.

Answer 2

print a function, so your code in Python 3 is calling center() on the return value of print function (which is None). Add one more pair of parenthesis:

print( ("|").center(11,'-') )

Answer 3

f字符串解决方案是；

print(f'{"|":-^11}')