[Tutor] Additional help

Brian van den Broek brian.van.den.broek at gmail.com
Sun Feb 10 22:15:04 CET 2013

On 10 February 2013 15:29, Ghadir Ghasemi <ghasemmg01 at leedslearning.net> wrote:
> Hi guys, I wondered if you knew what I could add to this code so that when the user enters 1 from the menu and then doesn't enter a valid binary number the program should ask them over and over again until valid binary number is entered.
> here is the code:


> while True:
>     show_menu()
>     choice = input("please enter an option: ")
>     if choice == '1':
>         binary = input("Please enter a binary number: ")
>         denary = 0
>         place_value = 1
>         for i in binary [::-1]:
>                     denary += place_value * int(i)
>                     place_value *= 2
>         print("The result is",denary)


>     elif choice == '3':
>      break

Hi Ghadir,

"over and over again until" suggests a while loop.

So, you need something like the pseudo-code:

while True:
    binary = input("Please enter a binary number: ")
    if isgood(binary):
        pass  # do stuff then break
        pass #remind user of constraints before they are prompted again

(This assumes you've an isgood function that will return a boolean as
the user input is acceptable. That's not necessarily the best way, but
it makes for easy pseduo-code and doesn't do the work for you ;-)

Last, a better subject line is a good idea. Pretty much every post
asking for help from someone who's posted before could have your
subject line.


Brian vdB

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