What does this type of syntax mean in a while loop declaration?

Question

while b:
   b -= 2

What is the condition in a line written like this? Does it default to while b > 0?

Here's a [related question](https://stackoverflow.com/q/39983695/4650297) that might help. — BruceWayne, Oct 08 '18 at 21:34
Why has **no one** mentioned that `b` *must be even and positive*, otherwise the code will run in an infinite loop? If this is satisfied, the code will execute until it reaches `0`, which will satisfy the `while` condition and exit the loop. — Sunny Patel, Oct 08 '18 at 22:31

score 0 · Answer 1 · answered Oct 08 '18 at 21:35

0

Your best bet is to try it. Try running:

b=10

while b:
    print(b)
    b-=2

and see what happens

answered Oct 08 '18 at 21:35

G. Anderson

o12d10 · Answer 2 · 2018-10-08T21:39:09.407

0

Yes, it sure does. b > 0.

b = 10
while b:
    print(b)
    b -= 1

A simple print() statement should let you know when the loop terminates.

Furthermore, this does not mean that the loop will not run for negative b < 0. This means that the loop will terminate then b = 0.

b = -1
while b:
    print(b)
    b -= 1

Goes into an infinite loop.

edited Oct 08 '18 at 21:39

answered Oct 08 '18 at 21:35

o12d10

1

Assuming `b` is a number, it means `b!=0`, rather than `b>0` – khelwood Oct 08 '18 at 21:37
You are right. Expanded the answers to account for your reasoning. Thanks. – o12d10 Oct 08 '18 at 21:39

score 0 · Answer 3 · answered Oct 08 '18 at 21:40

0

This basically checks if b is True, inside the while loop it does b -= 2

answered Oct 08 '18 at 21:40

Spandyie

3 Answers3