How do I make the user provide me with the correct inputs?

Question

site = input("Choose a site:\n 1.site1 2.site2")
while site!=1 and site!=2:
    print("Wrong input please choose between 1 and 2")
    site=input("Choose a site:\n 1.site1 2.site2")

Here I'm trying to make the user choose between the number 1 and the number 2 but for some reason I cant make it work, specifically when I use the correct numbers as input it wont get out of the while loop so the program can run, I've also tried the following with no luck:

site = input("Choose a site:\n 1.site1 2.site2")
while True:
    if(site==1 or site==2):
        break
    else:
        print("Wrong input please choose between 1 and 2")
        site=input("Choose a site:\n 1.site1 2.site2")

In Python 3.x `input` returns a string, so comparing it to an integer doesn't make sense and will always return `False`. — ForceBru, Dec 20 '19 at 17:27
@toolic There's no point trying to convert it to an `int` before you verify the input is valid; check against strings, then call `int` on a known valid choice. — chepner, Dec 20 '19 at 17:49
@chepner You are right, but I prefer to not call int at all instead verify the input using strings instead of integers because it throws an error if the user uses a string as an input,since the valid answer is either 1 or 2 it's not a problem using strings insted of integers. — ppcase, Dec 20 '19 at 18:00
@ppcase I'm not sure I follow. An input of `foo` should prompt the user for another input just as much as an input of `3`, rather than raising a `ValueError`. — chepner, Dec 20 '19 at 18:04
@chepner i'm not refering to the solution of Ed Ward, I've tried running the following while giving an input of "foo"(note that i'm new to stackoverflow hence the link):https://controlc.com/cfc3481e — ppcase, Dec 20 '19 at 18:14
Related: [Asking the user for input until they give a valid response](https://stackoverflow.com/questions/23294658/asking-the-user-for-input-until-they-give-a-valid-response). — martineau, Dec 20 '19 at 18:20

Ed Ward · Accepted Answer · 2019-12-20T17:56:13.397

1

For any input, you could try this function:

def enforced_input(prompt, options):
    if any([not type(i) == str for i in options]):
        raise ValueError("options should only contain string type")

    while True:
        result = input(prompt)
        if result in options:
            return result
        print("Please enter a valid input")

You can use it like this:

site = enforced_input("Choose a site:\n 1.site1 2.site2", ("1","2"))

Just remember that input returns a string, so make sure all your options are also strings, or it won't work.

edited Dec 20 '19 at 17:56

answered Dec 20 '19 at 17:37

Ed Ward

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1

Making `options` optional (or at least, this default value) doesn't make much sense. I'd rather get a traceback about a missing argument than a function that never returns. – chepner Dec 20 '19 at 17:52
good point... have edited – Ed Ward Dec 20 '19 at 17:56

score 0 · Answer 2 · answered Dec 20 '19 at 18:47

By defualt input() takes input as string to take input as int you can use int(input()) so your code will look like this

site = int(input("Choose a site:\n 1.site1 2.site2\n"))
while site!=1 and site!=2:
print("Wrong input please choose between 1 and 2")
site=input("Choose a site:\n 1.site1 2.site2\n")

How do I make the user provide me with the correct inputs?

2 Answers2