how to limit possible input while using raw_input? (also using split)

Question

i want to limit the users input in two cases:

1.With a string and split, when asking the user to put in two, 2 digit numbers I wrote:

x=raw_input("words").split()

I want to only enable him to write an input that is two 2 digit numbers, and if he does something else I want to pop an error, and for him to be prompted again, until done right.

2.This time an INT when asking the user for a random 4 digit number:

y=int(raw_input("words"))

I only want to allow (for example) 4 digit numbers, and again if he inputs 53934 for example I want to be able to write an error explaining he must only enter a 4 digit number, and loop it back until he gets it right.

Thank you, hopefully I explained myself properly.

update so - trying to start simple i decided that at first ill only try to ask the user to type in 8 letters. for example an qwertyui input is acceptable, but sadiuso (7 chars) is not.

so i tried working with the syntax you gave me and wrote:

y=raw_input("words") if not (len(y) == 8):
    pop an error

but im getting a syntax error on the :

falsetru · Accepted Answer · 2013-12-28 07:19:34Z

2

Use str.isdigit and len

>>> '12345'.isdigit()
True
>>> 'ab12'.isdigit()
False
>>> len('12')
2

while True:
    x = raw_input('Input 2 digits: ')
    if x.isdigit() and len(x) == 2:
        x = int(x)
        break
    print('input should be 2 digits.')

print('x = {}'.format(x))

edited Dec 28, 2013 at 7:19

answered Dec 28, 2013 at 4:39

falsetru

371k69 gold badges769 silver badges659 bronze badges

Sign up to request clarification or add additional context in comments.

10 Comments

Giladiald Over a year ago

ok i need a LITTLE more help here, even though this is a huge step in the right direction, would you mind showing me how exactly to input that into my code? still very new to this.

falsetru Over a year ago

@Giladiald, Put if statement after the raw_input line.

Leifingson Over a year ago

@falsetru, why use an if instead of an assert? I'm under the impression assert is more Pythonic by asking for forgiveness later..

falsetru Over a year ago

@Leifingson, See mail.python.org/pipermail/python-list/2013-November/660401.html

Leifingson Over a year ago

@falsetru, thanks, I had my suspicions about using assert which is why I asked, but how about a try-except? Maybe performance wise it'd be better to assume a correct input and catch a bad one..

|

Collectives™ on Stack Overflow

how to limit possible input while using raw_input? (also using split)

Thank you, hopefully I explained myself properly.

1 Answer 1

10 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

Thank you, hopefully I explained myself properly.

1 Answer 1

10 Comments

Your Answer

Sign up or log in

Post as a guest

Related