problems with looping, i suppose

Gary gary_e_green at yahoo.com
Mon Mar 27 21:37:57 CEST 2006


John --
I looked at your exercise.  As it appears in my browser, there appear
to be a couple of problems with the bottom "While" block.

0 Alignment problem with the "except" clause.
    As I'm sure you've already discovered, Python is "whitespace
sensitive".  If it looks like a block, it is; otherwise it isn't.  The
"if" .. "elif" statements aren't "inside" ("to the right of") the
"try".  Python will, I believe, interpret this as "try" with no
matching "except" or "finally" and will toss this as a syntax error --
and thus, I suspect, the flashing screen.

o logic error.
   if "guess" == "number", program as written will print "congrats"
forever.

Assuming my "cut, copy, paste" works ok, try this: (hmm, the print
"congrats" line looks like it's broken into two lines when I preview
this.  Please ignore -- it should all be on one line):

import random

number = random.choice(range(1, 100))
tries = 0

while True:
     try:
        guess = input('Enter a number between 1 and 100: ')
        break
     except NameError:
        print 'Invalid number\n'
        continue

while True:
        tries += 1
        try:
            if guess < number:
                guess = input('Too low. Try again: ')
            elif guess > number:
                guess = input('Too high. Try again: ')
            else:
                print 'Congratulations! You got it in
',tries,'guess(es).'
                break

        except NameError:
            print 'Invalid number\n'
            continue

raw_input()


I altered the "if" a bit -- just my own preference that an "if" always
have a matching "else".

If you're looking for something with an editor and a debugger -- try
"IDLE".  If your installation is like mine,  it's included.  Look in
your Python directory under Lib/idelib for file "idle.pyw".  (NB:  At
the moment, I'm running a WinXP box and that's where it is here.  My
poor old mind can't dredge up whether it's in the same relative place
in say, a Linux installation.)  "IDLE" isn't perfect but it'll get you
started.  (Also, FWIW, if you run this under "IDLE", you can omit the
trailing "raw_input()")

hope this helps.

gary


John Salerno wrote:
> John Salerno wrote:
> > Here's an exercise I was doing
>
> This might help:
>
> import random
>
> number = random.choice(range(1, 100))
> tries = 0
>
> while True:
>      try:
>      	guess = input('Enter a number between 1 and 100: ')
>      	break
>      except NameError:
>      	print 'Invalid number\n'
>      	continue
>
> while True:
> 	tries += 1
> 	try:
>      	if guess == number:
>      		print 'Congratulations! You got it in', tries, 'guess(es).'
>      		break
>      	elif guess < number:
>      		guess = input('Too low. Try again: ')
>      	elif guess > number:
>      		guess = input('Too high. Try again: ')
>      except NameError:
>      	print 'Invalid number\n'
>      	continue
> 
> raw_input()




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