[Tutor] FW: null inputs

[Hugo Arts]

On Thu, Mar 15, 2012 at 3:56 PM, James Reynolds <eire1130 at gmail.com> wrote:
>
>
> You can't prevent users from entering whatever they feel like it, but you
> can prevent your program from processing that input and force them to try
> again.
>
> The typical way this is done is through a while loop:
>
> age = ''
>
> while age != ''
>     age=raw_input("what age are you? ")
>
> this will continue to loop until you give it something other than ''.
>
> Of course, you can build on this, you know, something like:
>
> checker = False
>
> while checker:
>     age=raw_input("what age are you? ")
>     try:
>         age = int(age)
>         checker = True
>     except TypeError:
>       print "you didn't enter an integer for an age!"
>       print "try again!!!
>
>

Small correction: the exception you're looking for in this case is a
ValueError (after all, the argument provided has the correct type, but
its value can not be converted to an integer). int will throw
TypeError, but only if you supply an argument that is not a string or
number.

Hugo