thanks very much i get it now...............
> From: [email protected] > Date: Thu, 15 Mar 2012 16:03:12 +0100 > Subject: Re: [Tutor] FW: null inputs > To: [email protected] > CC: [email protected]; [email protected] > > On Thu, Mar 15, 2012 at 3:56 PM, James Reynolds <[email protected]> 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
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