While Loop Counter Confusion

Question

I'm working with while loops and I'm just a bit confused on how to break out of it in the way that I want. So I've nested a for loop within a while loop:

x = True
y = 0
while x:
  if y >= 5:
    x = False
    print('break')
  else:
      for x in range(7):
        y += 1 
        print('test')

The output that I'm looking for is 5 tests printed out and one break. However, every time I run the program it prints out 7 tests before it goes to the break. I'm not exactly sure, but I think I'm just confused about something within while loops! If someone could explain this to me please let me know :) I have found ways around this, but I'd like to get an understanding of why it doesn't work.

Jab · Accepted Answer · 2020-07-23 22:19:33Z

2

This is because it's performing the entire for loop within the while loop therefore y will become 7 before it checks again. Removing the for loop will resolve this.

x = True
y = 0
while x:
  if y >= 5:
    x = False
    print('break')
  else:
    y += 1 
    print('test')

answered Jul 23, 2020 at 22:19

Jab

27.6k22 gold badges82 silver badges117 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Luiz · Accepted Answer · 2020-07-23 22:23:25Z

2

y = 0
while y < 5:
  print("test")
  y += 1
print("break")

Would work.

There is no point in having another variable like "x" for the while loop when it allows for you to set the condition directly.

answered Jul 23, 2020 at 22:23

Luiz

1481 silver badge9 bronze badges

Comments

user13984269 · Accepted Answer · 2020-07-23 22:21:57Z

1

Because inner loop will complete before the next iteration of the outer loop. I.e. once the inner loop starts it does all 7 iterations before starting the next iteration of the while loop.

You can do this by just using one loop. Print out “test” increase counter and put in an if condition to break when counter is 5.

answered Jul 23, 2020 at 22:21

user13984269

Comments

jesal · Accepted Answer · 2020-07-23 23:22:29Z

0

The reason 7 tests print rather than 5 is that your entire for loop is executed before you go back to the beginning of your while statement. I think your understanding is that, after one iteration of a for loop, you go back to the beginning of the while loop, but this is incorrect: your for loop is executed completely before going back to the beginning of the while loop.

After you step into the for loop, you increment y 7 times and print test 7 times. y is now >= 5, and you go back into your if statement. The if statement turns x false, thereby "turning off" the while loop, and a break statement is printed. If you just want to print out 5 tests and one break, it would be much easier to simplify your code as such:

y = 0
while True:
    if y < 5:
        print('test')
        y += 1
    else:
        print('break')
        break

answered Jul 23, 2020 at 23:22

jesal

1181 silver badge15 bronze badges

1 Comment

annatn998 Over a year ago

Thank you this explanation was very clear and I can understand it a lot better now! really appreciate it :)

nagyl · Accepted Answer · 2020-07-23 22:19:49Z

0

Try

i = 0
while True:
    if i == 5:
        break
    print('test')
    i = i + 1

answered Jul 23, 2020 at 22:19

nagyl

1,6641 gold badge9 silver badges18 bronze badges

Collectives™ on Stack Overflow

While Loop Counter Confusion

5 Answers 5

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related