[Tutor] How to check if user input is an integer

[Alan Gauld]

On 29/03/13 11:33, Ghadir Ghasemi wrote:
> Hi guys I am trying to create part of a vending machine.

> when I entered a non integer like 'dfsdf', the program just broke.
 > Is there a way that the program can check if the input is an integer,

Yes you can use try/except to catch the failure.

> if it isn't the program just keeps asking for an input?

and a while loop will keep you circulating.

You may not have come across these in your tutorial/course yet

> fiftypencecoins = int(input("how many 50p coins do you want to insert or press 'e' to exit : "))
> if fiftypencecoins == 'e':
>          break

But this check needs to be before you convert to int() otherwise the 'e' 
will always raise an error when you try to convert it!

> else:
>       currentmoney += fiftypencecoins * 5/10
>       print("your newly updated credit is £" + str(currentmoney) + "0")

So in pseudo code you should have

while True:
    read input
    if exit condition break
    try: convert to int
    except ValueError: continue
    process the value

HTH
-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/