for loop vs while loop question.

[Milo Daemon]

Hi, i am extremely new to python and i've been following a tutorial about learning to programm with python. After reading through the tutorial and answering the questions given by it i findally came to a question which i can't figure out!
***Warning: Extremely noobish, i know this***
the question is:
Write a program that continually reads in numbers from the user and adds them together until the sum reaches 100. Write another program that reads 100 numbers from the user and prints out the sum.

... i really got stuck here ... i would be happy if i just got the answer to this one so i could see it and start to understand and apply the solution myself.

If you do chose to respond and help me out : Thanks a lot!

(P.S i'm going on a holiday tomorrow (19.7.2007) so i will not respond for a long time ... still i'm sort of hoping i can get a reply really fast ...)

[bvdet]

Hi, i am extremely new to python and i've been following a tutorial about learning to programm with python. After reading through the tutorial and answering the questions given by it i findally came to a question which i can't figure out!
***Warning: Extremely noobish, i know this***
the question is:
Write a program that continually reads in numbers from the user and adds them together until the sum reaches 100. Write another program that reads 100 numbers from the user and prints out the sum.

... i really got stuck here ... i would be happy if i just got the answer to this one so i could see it and start to understand and apply the solution myself.

If you do chose to respond and help me out : Thanks a lot!

(P.S i'm going on a holiday tomorrow (19.7.2007) so i will not respond for a long time ... still i'm sort of hoping i can get a reply really fast ...)

Here's the first one. The second one will be similar. [code=Python]numsum = 0
while numsum < 100:
numsum += int(raw_input(' Enter a number'))

print 'The sum of the numbers you entered is %d.' % numsum[/code]HTH :)

[bartonc]

Two (of many) ways to do the second one:[code=Python]numsum = 0
for i in range(100):
numsum += int(raw_input(' Enter a number'))

print 'The sum of the numbers you entered is %d.' % numsum[/code]
or[code=Python]numsum = 0
i = 0
while i < 100:
numsum += int(raw_input(' Enter a number'))
i += 1

print 'The sum of the numbers you entered is %d.' % numsum[/code]

I need to give this thread a new name, so let us know when you have read it. Thanks.

[Milo Daemon]

ah ok love y'all i read it & thx

[bartonc]

ah ok love y'all i read it & thx

I'm glad that you were able to dig up your thread (I was worried that you'd be unable).

Now I can rename it.


Welcome back!

[Milo Daemon]

I'm glad that you were able to dig up your thread (I was worried that you'd be unable).

Now I can rename it.


Welcome back!

I know sorry, long holiday -_- (added it 2 favourites so dont think it would have been that much of a problem tho)

[William Manley]

I have a question thats not exactly related to the original topic, but is sorta related to the new name of the topic :P

are there any differences in speed when executing a for loop or a while loop? It seems to me that for loops complete faster but I have no real way of testing it, I don't think. Was wondering if others experianced the same thing.

[bartonc]

I have a question thats not exactly related to the original topic, but is sorta related to the new name of the topic :P

are there any differences in speed when executing a for loop or a while loop? It seems to me that for loops complete faster but I have no real way of testing it, I don't think. Was wondering if others experianced the same thing.

The results are a bit surprising: (Bare in mind that the import actually takes up over half of the times posted) I would have expected the call to range() to be the bottleneck.
test3.py:[CODE=python]def forLoopTest(n):
for i in range(n):
pass

def whileLoopTest(n ):
i = 0
while i < n:
i += 1
[/CODE]

TimeTestModule. py:[CODE=python]import timeit

test1ExecStr = \
"""from test3 import forLoopTest; forLoopTest(10) """

t = timeit.Timer(te st1ExecStr)
print t.timeit()

# 14.056588477

test2ExecStr = \
"""from test3 import whileLoopTest; whileLoopTest(1 0)"""

t = timeit.Timer(te st2ExecStr)
print t.timeit()

# 13.6136176525[/CODE]

[ilikepython]

The results are a bit surprising: (Bare in mind that the import actually takes up over half of the times posted) I would have expected the call to range() to be the bottleneck.
test3.py:[CODE=python]def forLoopTest(n):
for i in range(n):
pass

def whileLoopTest(n ):
i = 0
while i < n:
i += 1
[/CODE]

TimeTestModule. py:[CODE=python]import timeit

test1ExecStr = \
"""from test3 import forLoopTest; forLoopTest(10) """

t = timeit.Timer(te st1ExecStr)
print t.timeit()

# 14.056588477

test2ExecStr = \
"""from test3 import whileLoopTest; whileLoopTest(1 0)"""

t = timeit.Timer(te st2ExecStr)
print t.timeit()

# 13.6136176525[/CODE]

When I run the same code with 50 iterations. The for loop is definately faster than the while loop. (6.9 - 7.1 vs. 10.2 - 10.5). Changing the range() call to xrange() makes the for loop even faster (6.0 - 6.2).

[bartonc]

<snip> Changing the range() call to xrange() makes the for loop even faster (6.0 - 6.2).

Great catch, my friend. I forgot about that one. Thanks.

[William Manley]

Thanks for those, I *must* remember the timeit module.

At the time I thought it was just lag (I was using the for loops vs while loops in my irc bots, with 3 channels spamming it on purpose) but now it know for sure.

Thanks again,
Will.