为什么在 Python 中打印函数的返回值？

Question

Very new to python, trying this -

def newlines():
    print()
    print()
    print()    
question = "Which online Course you have signed up, dude?"
response = "Good Luck to you, dude!"
print(question), newlines(), input(), newlines(), print(response)

In Python 3.2.* the output is this

Which online Course you have signed up, dude?



Nothing



Good Luck to you, dude!

(None, None, "Nothing", None) # Where this output is coming from ?

Also this is not happening with python 3.3 beta

Answer 1

You must be at the interactive shell. When I run your code as a file, I get this output:

$ python3.2 test.py
Which online Course you have signed up, dude?



dlkjdf



Good Luck to you, dude!
$

You only get your output at the console:

>>> def newlines():
...     print()
...     print()
...     print()    
... 
>>> question = "Which online Course you have signed up, dude?"
>>> response = "Good Luck to you, dude!"
>>> 
>>> print(question), newlines(), input(), newlines(), print(response)
Which online Course you have signed up, dude?



dljdldk



Good Luck to you, dude!
(None, None, 'dljdldk', None, None)
>>> 

This is because the console will print the representation of the last thing you typed in. The last statement is actually a tuple, so it gets printed at the end. Here's some examples:

>>> 3
3
>>> 4
4
>>> 3, 4, None, "hey"
(3, 4, None, 'hey')

Answer 2

When you write this:

print(question), newlines(), input(), newlines(), print(response)

It is actually a tuple, which holds the result of each function.

Simply breaking up the calls on individual lines will solve your problem.

print(question)
newlines()
input()
newlines()
print(response)