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Re: Error Testing

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On Sat, Oct 19, 2013 at 11:23 PM, Scott Novinger <scnovinger@gmail.com> wrote:
>     # Create the variable for radius, "radius".
>     print('Please enter the circle radius and press ENTER:')
>     radius = input()
>
>     # Check to make sure the entered value is an integer.
>     if type(radius) != type(int):
>         print('You must enter an integer value.')
>         print('Please enter the circle radius and press ENTER:')
>         radius = input()
>     else:
>         print('The radius you entered is: ' + radius)
>
>     radius = int(radius)
>
> Thanks for your help. I'm using Python v3.2 for windows.

In Python 3, the input() function always returns a string. Your type
check is never going to succeed. Also, you're not checking what you
think you're checking; you're actually looking to see if input()
returned a type, because the type of int is type:

>>> type(int)
<class 'type'>

You might want:

if type(radius) != int:

But that still won't work, because input() will always return a string:

>>> radius = input()
42
>>> type(radius)
<class 'str'>

You can try all these out in the interactive interpreter (you probably
have IDLE installed, which on Windows is rather nicer to work with
than the default interactive mode).

A better check would be to just try to turn the inputted value into an
integer, and fail if that doesn't work. Again, try this interactively:

>>> int("42")
42
>>> int("not an integer")
Traceback (most recent call last):
  File "<pyshell#58>", line 1, in <module>
    int("not an integer")
ValueError: invalid literal for int() with base 10: 'not an integer'

With a couple of quick checks, you can easily see what happens if the
conversion fails, and then you can deal with that failure. So
effectively, just drop the whole if: block, go straight to the "radius
= int(radius)" line, and deal with the error there.

ChrisA

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Error Testing Scott Novinger <scnovinger@gmail.com> - 2013-10-19 05:23 -0700
  Re: Error Testing Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-19 13:37 +0100
    Re: Error Testing Scott Novinger <scnovinger@gmail.com> - 2013-10-19 06:34 -0700
      Re: Error Testing Chris Angelico <rosuav@gmail.com> - 2013-10-20 00:42 +1100
      Re: Error Testing rusi <rustompmody@gmail.com> - 2013-10-19 09:22 -0700
        Re: Error Testing Chris Angelico <rosuav@gmail.com> - 2013-10-20 09:28 +1100
        Re: Error Testing Ned Deily <nad@acm.org> - 2013-10-19 15:46 -0700
        Re: Error Testing Chris Angelico <rosuav@gmail.com> - 2013-10-20 10:02 +1100
        Re: Error Testing Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-10-20 12:18 -0400
  Re: Error Testing Ned Batchelder <ned@nedbatchelder.com> - 2013-10-19 08:44 -0400
    Re: Error Testing Roy Smith <roy@panix.com> - 2013-10-19 08:57 -0400
      Re: Error Testing Chris Angelico <rosuav@gmail.com> - 2013-10-20 00:04 +1100
      Re: Error Testing Ned Batchelder <ned@nedbatchelder.com> - 2013-10-19 09:07 -0400
        Re: Error Testing Roy Smith <roy@panix.com> - 2013-10-19 09:09 -0400
      Re: Error Testing Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-19 14:19 +0100
  Re: Error Testing Chris Angelico <rosuav@gmail.com> - 2013-10-20 00:01 +1100
  Re: Error Testing David Robinow <drobinow@gmail.com> - 2013-10-19 14:08 -0400
  Re: Error Testing Tim Chase <tim@thechases.com> - 2013-10-19 13:31 -0500
  Re: Error Testing Terry Reedy <tjreedy@udel.edu> - 2013-10-19 15:50 -0400
  What's wrong with Windows Command Prompt (was Re: Error Testing) Terry Reedy <tjreedy@udel.edu> - 2013-10-19 16:35 -0400
  Re: What's wrong with Windows Command Prompt (was Re: Error Testing) Chris Angelico <rosuav@gmail.com> - 2013-10-20 09:15 +1100
  Re: Error Testing Chris Angelico <rosuav@gmail.com> - 2013-10-20 09:20 +1100
  Re: What's wrong with Windows Command Prompt (was Re: Error Testing) David Robinow <drobinow@gmail.com> - 2013-10-21 15:55 -0400
  Re: What's wrong with Windows Command Prompt (was Re: Error Testing) Tim Chase <python.list@tim.thechases.com> - 2013-10-21 15:29 -0500

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