Why Can't I break out of the loop?

Question

Python beginner here. Sorry if it's a basic python concept

over = False

def run():
    user_input = input("Over? (y/n): ")
    if(user_input == 'y'):
        over = True

while not over:
    run()

Although the input is 'y' the loop doesn't stop.

Please read python scoping rules here -> http://stackoverflow.com/questions/291978/short-description-of-the-scoping-rules — JkShaw, Apr 29 '17 at 16:47

score 1 · Accepted Answer · answered Apr 29 '17 at 16:45

1

You need to write global over, so function run() will change global variable

over = False

def run():
    global over
    user_input = input("Over? (y/n): ")
    if(user_input == 'y'):
        over = True

while not over:
    run()

answered Apr 29 '17 at 16:45

Sklert

242
5
12

score 1 · Answer 2 · answered Apr 29 '17 at 16:49

You shouldn't be using a global variable here. Return a boolean, and call run as the condition of the loop. (At this point, you may want to reconsider the name run as well.)

def run():
    user_input = input("Over? (y/n)")
    return user_input == 'y'

while run():
    ...

score 0 · Answer 3 · answered Apr 29 '17 at 16:48

0

You are setting the local variable over inside the function run(), but you aren't passing it out to the scope from which it was called. Instead return the value to the calling scope like this:

over = False

def run():
    user_input = input("Over? (y/n): ")
    if(user_input == 'y'):
        over = True
    else:
        over = False
    return over

while not over:
    over = run()

answered Apr 29 '17 at 16:48

Craig

4,605
1
18
28

You can (and should) remove the entire `if/else` clause and simply do `return user_input == 'y'`. – Tim Pietzcker Apr 29 '17 at 16:50

Why Can't I break out of the loop?

3 Answers3