exiting a while loop

[Peter Otten]

John Yeadon via Python-list wrote:

> Am I unreasonable in expecting this code to exit when required?

It is unreasonable to expect something that doesn't match what you read in 
the tutorial ;)

If you want to terminate the script you can use exit. However exit is a 
function, and you have to call it

exit()

to actually do anything.

If you want to terminate just the loop, which is more likely because there 
is a print() following it, you can do this with break (which is a statement, 
so no trailing ()):


> # Add up the powers of 2 starting with 2**0 until 2 million is met.
> n = 1
> target = 2000000
> sum = 0
> 
> while True:
>      x = 2 ** (n - 1)
>      sum += x
>      print(n, sum)
>      if sum >= target:
>          print("Target met.")

           break

>      n += 1
> 
> print("\n", n, "terms are required.")