This while loop wont run?

Question

I’ve been doing some basic practice exercises for python, and so far it has been quite smooth flowing and such though I’ve run into a problem where the second while loop will not run. So far I’ve re-indented, defined the whole second and tried putting parameters on the loop where done = True, while done == True:, done = False
(later on in the code was what I previously had down but I removed it in effort to get it working.)

P.S some advice on my code would be greatly appreciated if you feel it necessary, as tbh I’m just winging it as I’ve been teaching myself how to code in python. I’ve included the first while loop too, as I figured that far down the code may be cause for the problem unknowingly.

import random
Olist = []
while True:
counter = 0
counter2 = 0
print("nWelcome to exercise 05")
InH1 = str(input("nDo you wish to continue? (y/n):"))
if InH1 == 'y':
    list1 = random.sample(range(30), 11)
    list2 = random.sample(range(30), 9)
    print("n<><>Two random lists have been generated.<><>")
    print(list1)
    print(list2)
    max_index = len(list2)-1
    print("n<><>Max index has been generated.<><>")
    InD = str(input("nStart the func? (y/n):"))
    if InD == 'n':
        break
    if InD == 'y':
        while True:
            if counter2 == 11:
                print(Olist)
                InL = str(input("nEnter any key to return to the start of the program,
                                  or,n enter 'q' to break the program."))
                if InL == 'q':
                    break
            if list1[counter2] == list2[counter]:
                Olist.append(list2[counter])
                counter + 1
            elif counter == 10:
                counter = 0
            else:
                counter + 1
if InH1 == 'n':
    break

Asked By: ZZnN

||

Source

Answer 1

You wrote:

while True:
counter = 0
counter2 = 0

counter = 0 is OUTSIDE of the while-loop

Did you want the following?

while True:
   counter = 0
   counter2 = 0

Answered By: Samuel Muldoon

Answer 2

if list1[counter2] == list2[counter]:
                Olist.append(list2[counter])
                counter + 1
            elif counter == 10:
                counter = 0
            else:
                counter + 1

I think your counter + 1 statements are causing you serious trouble. Really take a close look there… Don’t you mean counter = counter + 1?

Answered By: TomServo

Answer 3

A few details:

there is no action on counter2 after you assign counter2 = 0 so you will never enter the if counter2 == 11 branch [unreachable] and – unless needed somewhere else – you can completely remove that part
as said by Tom you have to ask the counter increment as counter = counter + 1 or with the short form counter += 1
you have to control also that counter doesn’t get over the max_index or you will try to fetch an unexisting element in the array generating an "IndexError: list index out of range" from the if list1[counter2] == list2[counter] line before counter can be reset by the following elif branch
you need to create a condition to stop the second loop or you will not come to an end of the program: this is why I modified it into while counter < max_index:: the same line will allow you to safely remove the elif branch of the previous point too
I left the first loop constantly running to start over indefinitely

This code should be fine for your target:

import random
Olist = []

while True:
    counter = 0
    counter2 = 0
    print("nWelcome to exercise 05")
    InH1 = str(input("nDo you wish to continue? (y/n):"))

    if InH1 == 'y':
        list1 = random.sample(range(30), 11)
        list2 = random.sample(range(30), 9)
        print("n<><>Two random lists have been generated.<><>")
        print(list1)
        print(list2)
        max_index = len(list2)-1
        print("n<><>Max index has been generated.<><>")
        print(max_index)
        InD = str(input("nStart the func? (y/n):"))
        if InD == 'n':
            break
        if InD == 'y':
            print(list1[counter2])
            print(list2[counter])
            while counter < max_index:
                if counter2 == 11:
                    print(Olist)
                    InL = str(input("nEnter any key to return to the start of the program,
                                  or,n enter 'q' to break the program."))
                    if InL == 'q':
                        break
        
                if list1[counter2] == list2[counter]:
                    Olist.append(list2[counter])
                    counter += 1
                else:
                    counter += 1

    if InH1 == 'n':
        break

Answered By: Antonino

This while loop wont run?

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