Why does this Spam Code run unlimited times?

Question

Got an exam in python in two days, pretty basic stuff. This is the code given in an exercise

spam = 0
while spam < 5:
    print('Hello, world.')
spam = spam + 1

I would have expected it to run until it hits 5 (so with the +1 given in the last line 2 times) But the answer is "Unlimited times".

Anyone knows why? :) Is ir because there is no elif condition in this example?

Answer 1

Let's break down the code line by line.

First you have

spam = 0

This sets the variable spam equal to the value 0. And it will always stay that value until explicitly changed by the code.

Then we have a while loop

while spam < 5:
    print('Hello, world.')

This literally means while the value of spam is less than 5 keep calling print('Hello World'). However, spam is equal to 0, so it being smaller than 5 is true and will always be true. This loop also does not change the value so the loop will run indefinitely.

Finally, we have

spam = spam + 1

This staments increments spam by 1, but the problem is that this statement is never reached! I.e. it is placed after a loop that runs indefinitely!

Answer 2

In python, indentation matters. Try this:

spam = 0
while spam < 5:
    print('Hello, world.')
    spam = spam + 1

If you don't ident the line spam = spam + 1 Python will interpret it as being out of the while block, therefore it is not executed and it stays on an endless loop.