loops

[Steven D'Aprano]

On Sat, 18 Oct 2008 20:45:47 -0700, John Machin wrote:

> On Oct 19, 2:30 pm, Steven D'Aprano <st... at REMOVE-THIS-
> cybersource.com.au> wrote:
> [snip]
>> making your code easy to read and easy to maintain is far more
>> important.
>>
>> for x in (2**i for i in xrange(10)):
>>     print x
>>
>> will also print 1, 2, 4, 8, ... up to 1000.
> 
> I would say up to 512; perhaps your understanding of "up to" differs
> from mine.

Well, mine is based on Python's half-open semantics: "up to" 1000 doesn't 
include 1000, and the highest power of 2 less than 1000 is 512.

Perhaps you meant "up to and including 512".



> Easy to read? I'd suggest this:
> 
> for i in xrange(10):
>     print 2 ** i


Well, sure, if you want to do it the right way *wink*. 

But seriously, no, that doesn't answer the OP's question. Look at his 
original code (which I assume is C-like pseudo-code):

for x=1;x<=100;x+x:
    print x

The loop variable i takes the values 1, 2, 4, 8, etc. That's what my code 
does. If he was asking how to write the following in Python, your answer 
would be appropriate:

for x=1;x<=100;x++:
    print 2**x



-- 
Steven