do you guys help newbies??

[Robin Munn]

Wojtek Walczak <gminick at hacker.pl> wrote:
> Dnia Wed, 27 Nov 2002 15:53:20 GMT, Robin Munn napisa³(a):
>> You could also do this in one step, like:
>>     gallonsPerTank = int(raw_input("Enter how many gallons..."))
> It of course works, but there's a large amount of situations to think of.
> 
> ---
> import sys
> try:
>    while 1:
>       a = raw_input("Put a digit here: ")
>       if not a.isdigit():
>          a = raw_input("Put a digit here: ")
>       else:
>          a = int(a)
>          break
> except:
>    print sys.exc_info()[1]
>    sys.exit()
> 
> print a
> ---
> 
> Any ideas to make it more reliable ?
> 

You're trying too hard. Let Python do the error-catching for you.

    try:
        a = int(raw_input('Enter your number: '))
    except ValueError:
        print "I asked for a number."

Or, if you want to loop until the user types in valid input:

    while 1:
        try:
            a = int(raw_input('Enter your number: '))
        except ValueError:
            print "That wasn't a number."
        else:
            break

This is almost exactly like the code you posted, except that the
isdigit() test was completely unnecessary. Let int() catch your errors
for you -- that's what exceptions are for.

-- 
Robin Munn <rmunn at pobox.com>
http://www.rmunn.com/
PGP key ID: 0x6AFB6838    50FF 2478 CFFB 081A 8338  54F7 845D ACFD 6AFB 6838