Issue with python lists and loops

Question

I am starting to learn python, and playing around with loops and lists. I can't understand how this doesn't continue till printing "The end"

x = [1,2,3,4]
for n in x:
    if len(x) > 0:
        x.pop(0)
        print(x)
    else:
        break
        print("The end")

I get:

[2, 3, 4]
[3, 4]

It is because `break` let's the program go leave the for-loop without executing any line after it (the print line). place the `print("The end")` in front of `break`! — Gwang-Jin Kim, Dec 11 '21 at 23:54

score 2 · Accepted Answer · answered Dec 11 '21 at 23:56

There's two bigger issues here.

Don't modify an iterable as you loop over it. This makes the execution extremely difficult to rationalize about and can cause a lot of weird behavior.
You put a break before the print. The break statement will exit the loop before you reach the print line.

Instead I would perform this action with a while loop, and do the end condition after the loop:

x = [1,2,3,4]
while len(x) > 0:
    x.pop(0)
    print(x)
print("The end")

[2, 3, 4]
[3, 4]
[4]
[]
The end

1 Answers1