Break or continue a while loop from a function

Question

I'm trying to have a while loop ask a series of question and restart when the last question is asked. The thing is, I want the user to have the ability to quit by typing a specific word at any question. I also want as little code as possible in the loop, so the if/elif statements lays in functions.

My question is: Can I continue or break a loop from a function?

My code:

def check_gender(q):
    if q == "f":
       number_women = number_women + 1
    elif q == "m":
        number_men = number_men + 1
    elif q == "foo":
        #break the loop
    else:
        print("Please answer M or F: ")
        q = input("Are you a male or female (M/F)? ").lower()
        check_gender(q)



def check_age(q):
    if not(16 <= int(q) <= 25):
        print("You are not in the age range for this survey")
    #Jump back to first question here
    if q == "foo":
        #break the loop

while True:
    gender = input("Are you a male or female (M/F)? ").lower()
    check_gender(gender)

    age = input("Please enter your age: ")
    check_age(age) 

    #And so on with questions

Is this possible?

Your code isn't properly indented; could you fix that?

David Z
– David Z

2017-10-04 18:34:14 +00:00
Commented Oct 4, 2017 at 18:34 — David Z
– David Z, Commented Oct 4, 2017 at 18:34

amarynets · Accepted Answer · 2017-10-04 18:34:47Z

4

You can return some(for example bool) value from function check_age(q) and check it.

def check_age(q):
    if not(16 <= int(q) <= 25):
        print("You are not in the age range for this survey")
    #Jump back to first question here
    if q == "foo":
        return True
    else:
        return False
while True:
    gender = input("Are you a male or female (M/F)? ").lower()
    check_gender(gender)

    age = input("Please enter your age: ")
    if check_age(age):
        break

answered Oct 4, 2017 at 18:34

amarynets

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Comments

Bart Van Loon · Accepted Answer · 2017-10-04 19:08:44Z

The best way probably is to raise a custom Exception from inside the question functions as follows:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

NUMBER_MEN, NUMBER_WOMEN = 0, 0


class ExitLoop(Exception):

    pass


def check_gender(reply):
    global NUMBER_WOMEN, NUMBER_MEN
    while True:
        if reply == "f":
            NUMBER_WOMEN += 1
            return
        elif reply == "m":
            NUMBER_MEN += 1
            return
        elif reply == "foo":
            raise ExitLoop
        else:
            print("Please answer M or F: ")
            reply = input("Are you a male or female (M/F)? ").lower()


def check_age(reply):
    if reply == "foo":
        raise ExitLoop
    if not 16 <= int(reply) <= 25:
        print("You are not in the age range for this survey")
        return False
    return True


while True:
    try:
        gender = input("Are you a male or female (M/F)? ").lower()
        check_gender(gender)

        age = input("Please enter your age: ")
        inrange = check_age(age)
        if not inrange:
            continue
    except ExitLoop:
        break

I made a few other changes to your code to make it a bit more pythonic. Be careful by the way, the code above fails when the user enters anything but 'foo' or a number in reply to the age question.

By the way, if you want to ask your user a lot of questions, you might want to check out the excellent Click package.

Hope this helps!

Bart Van Loon · Accepted Answer · 2017-10-04 19:29:47Z

You should try this code, is someone put other letter the loop will break

def check_gender(q):
    if q == "f":
        number_women = number_women + 1
    elif q == "m":
        number_men = number_men + 1
    # elif q == "foo":
         #break the loop
    else:
        print("Please answer M or F: ")
        q = input("Are you a male or female (M/F)? ").lower()
        check_gender(q)



def check_age(q):
    if not(16 <= int(q) <= 25):
        print("You are not in the age range for this survey")
    #Jump back to first question here
    #if q == "foo":
        #break the loop

while True:
    gender = input("Are you a male or female (M/F)? ").lower()
    if gender != "f" and gender != "m":
        break
    else:
        check_gender(gender)

    age = input("Please enter your age: ")
    try:
        ageValue = int(age)
        check_age(age)
    except ValueError:
        print ("You must enter a number")
        break

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