Python: Loop continues even when user quits

Question

I have been working on a project and I came across this problem in my program and was wondering if somebody is able to tell me a fix. Here I have to take input from the user the number of times they want the program to run. I do take inputs during the course of my loop and run the loop in range N (the number of times the user wants the program to run), but I terminate the program when 1 < N < 100. Here is sample code -

n = int(input("Number of times you want the program to run - "))
if n <= 0 or n >= 100 : 
    print("Number entered too large/big")
    quit()

for i in range(n):
    string = input("Enter a word - ")
    print(i)

I have tried running the code without the input and it all runs fine but as soon as I start taking inputs the program malfunctions. When I enter N less than zero the program quits and when N in the valid range the program works fine but when N > 100 the program continues till completion and the closes the console (working in Spyder). Would really appreciate some help :)

code snippet which u have mentioned has no problem and it works fine — Srinath gunnu, Sep 17 '19 at 10:32

score 0 · Answer 1 · answered Sep 17 '19 at 10:37

So i found the problem with the code, the quit() doesn't do anything, hence whenever you enter any value, the for loop will always run.

Now why does quit() work for when n<=0? Easy answer, it doesn't. When you enter for i in range(n) and if n <= 0 for example n= -3, then this is what the for loop resolves to

i=0
while i < n:
   i += 1

so when n = -3 or n<=1 then for loop never executes, thus acting as if the quit() worked. To get it to work, either use sys.exit to shut python file, or do something like

n = int(input("Number of times you want the program to run - "))
if n <= 0 or n >= 100 : 
    print("Number entered too large/big")
else:
    for i in range(n):
        string = input("Enter a word - ")
        print(i)

This code works as desired

P.S As to why quit() doesn't work, that i wouldn't know, i have never used spyder and hence haven't come across the quit() function

Thanks. The sys.exit solved my problem but why doesn't the quit() work? Isn't quit() also used for terminating the program/console? — Pythaconda, Sep 17 '19 at 10:43
That i am not really sure of, could be spyder specific issues, i dont have experience with that, apologies in that regard :) — Imtinan Azhar, Sep 17 '19 at 10:44
You may refer to this for understanding why quit doesn't work https://stackoverflow.com/questions/19747371/python-exit-commands-why-so-many-and-when-should-each-be-used/19747562 — Imtinan Azhar, Sep 17 '19 at 10:48

Python: Loop continues even when user quits

1 Answers1