How to break a while loop upon an empty input python?

Question

I have a code where the user is asked to input two integers, separated by a " ". This should continue as long as the user does not input anything, causing a ValueError, and breaking the While loop. However, I can't figure out what am I doing wrong:

def syote():
 koepisteet_all = []
 harjoitukset_all = []
 while True:
    koepisteet, harjoitukset = input('Koepisteet ja harjoitusten määrä: ').split()
    if ValueError:
        break
    else:
        koepisteet_all.append(koepisteet)
        harjoitukset_all.append(harjoitukset)


print(koepisteet_all)
print(harjoitukset_all) 

if __name__ == "__main__":
     
syote()

As wished, I do get a ValueError "ValueError: not enough values to unpack (expected 2, got 0)", but the code stops running.

I don't get it : you say "should continue" and "break the loop" at the same time, should it ask again or stop ? — azro
With the current indentation, thet function syote() ends after the while loop. Did you want the two print statements to be executed after the loop? Then you have to indent them correctly. — jps

azro azro · Accepted Answer · 2022-01-04T18:22:36

You need a try/except structure :

if a ValueError is raises (because of wrong input), then stop with break
if 2 values are given, save them

def syote():
    koepisteet_all, harjoitukset_all = [], []
    while True:
        try:
            koepisteet, harjoitukset = input('Koepisteet ja harjoitusten määrä: ').split()
            koepisteet_all.append(koepisteet)
            harjoitukset_all.append(harjoitukset)
        except ValueError:
            break

    print(koepisteet_all)
    print(harjoitukset_all)

How to break a while loop upon an empty input python?

1 Answers