[Tutor] Why does counting to 20 million stress my computer?

[Dick Moores]

Danny Yoo wrote at 10:21 7/16/2004:
>An alternative solution is to use a while-loop, something like:
>
>###
>counter = 0
>while counter < 10:
>     print "counter is:", counter
>     counter = counter + 1
>###
>
>
>Using range() on large numbers is a common gotcha, so don't worry too much
>about not knowing about xrange().  There are a few things that work
>perfectly well on small things, but break down when the problem grows much
>larger; range() is one of those.

Thanks, Danny.

I found an egregious error in the spin.py I posted earlier. It had k 
being augmented inside the range() loop. I took this line out, used 
xrange() instead of range(), and for a speed comparison, added the loop 
you suggested as another way.

Here are some results:

integer: 1000000 (1,000,000)
Counting..
0 to 1000000 in 0.141 seconds!
And now counting using a different loop..
0 to 1000000 in 0.406 seconds!

integer: 10000000 (10,000,000)
Counting..
0 to 10000000 in 1.500 seconds!
And now counting using a different loop..
0 to 10000000 in 4.016 seconds!

integer: 50000000 (50,000,000)
Counting..
0 to 50000000 in 7.188 seconds!
And now counting using a different loop..
0 to 50000000 in 19.110 seconds!

integer: 100000000 (100,000,000)
Counting..
0 to 100000000 in 15.078 seconds!
And now counting using a different loop..
0 to 100000000 in 40.204 seconds!

integer: 1000000000 (1,000,000,000)
Counting..
0 to 1000000000 in 148.859 seconds!
And now counting using a different loop..
0 to 1000000000 in 397.484 seconds!

Here's some info on my Dell desktop (thanks to Belarc Advisor):
2.80 gigahertz Intel Pentium 4
8 kilobyte primary memory cache
512 kilobyte secondary memory cache

Bus Clock: 533 megahertz

512 Megabytes Installed Memory

=======================================
#spin2.py

import time
print """
    Enter an integer to count to from zero.
    To quit, enter x or q.
    """

while True:
     # for exiting via ^C or ^D
     try:
         max = raw_input("integer: ")
     except (TypeError, EOFError):
         print "Bye."
         break
     if len(max) == 0:
         print "Hey, don't just hit Enter, type an integer first!"
         continue
     if max in ["q", "x"]:
         print "Bye."
         break
     try:
         max = int(max) + 1
     except:
         print "That's not an integer!"
         continue
     print "Counting.."
     tStart = time.time()
     for k in xrange(max):
         pass
     tEnd = time.time()
     print "0 to %d in %.3f seconds!" % (k, (tEnd - tStart))

     print "And now counting using a different loop.."
     c = 0
     tStart = time.time()
     while c < max -1 :
         c += 1
     tEnd = time.time()
     print "0 to %d in %.3f seconds!" % (c, (tEnd - tStart))
================================