Python function calling

Question

I've only started learning Python. If I wrote:

def questions(): 
    sentence= input(" please enter a sentence").split()

How would I end the function If the user didn't input anything and just hit enter

The function will end on its own since it is complete after any user input. if sentence == []: print('No user input detected') is something you may be looking for, though. — Stephen B
– Stephen B, Commented Sep 22, 2016 at 16:05

Patrick Haugh · Accepted Answer · 2016-09-22 16:08:19Z

1

def questions():
    sentence= input(" please enter a sentence").split()
    if sentence == []:
        #This is what happens when nothing was entered
    else:
        #This happens when something was entered

answered Sep 22, 2016 at 16:08

Patrick Haugh

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2 Comments

Jacob Vlijm Over a year ago

You could shorten it to if sentence:

Patrick Haugh Over a year ago

Yeah, but I wanted to make it clear that .split() returns a list and not a string.

TigerhawkT3 · Accepted Answer · 2016-09-22 16:09:32Z

1

Did you test this? The function will work properly if the user simply hits Enter. The sentence variable would be an empty list. If there was nothing else in the function, it would return None, the default return value. If you wanted to do further processing that requires an actual sentence with content, you can put if not sentence: return after that line.

answered Sep 22, 2016 at 16:09

TigerhawkT3

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3 Comments

roganjosh Over a year ago

This fails with SyntaxError: unexpected EOF while parsing in Python 2 btw unless they use raw_input

TigerhawkT3 Over a year ago

@roganjosh - That's fine; nobody uses input in Python 2 anyway, and they shouldn't be using Python 2 in the first place. :P I answer based on the current standard, which is Python 3, unless specified otherwise.

roganjosh Over a year ago

Um, I've ended up being stuck in Python 2 so my instinct is to answer along that vein :P But also, many tutorials will work with Python 2 so for beginner questions I would definitely anticipate such things!

Sayali Sonawane · Accepted Answer · 2016-09-22 16:08:33Z

0

You can add exception in your code. If you want to raise an exception only on the empty string, you'll need to do that manually:

Example

 try:
    input = raw_input('input: ')
    if int(input):
        ......
except ValueError:
    if not input:
        raise ValueError('empty string')
    else:
        raise ValueError('not int')

try this, both empty string and non-int can be detected.

answered Sep 22, 2016 at 16:08

Sayali Sonawane

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2 Comments

Jacob Vlijm Over a year ago

OP is using python3 :)

roganjosh Over a year ago

@JacobVlijm How do you know that? I didn't get a response to my question.

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