Defining a function that only accepts an integer as an input

Question

My approach with this function is that it only accepts an integer as an input, otherwise if the person enters a letter or something else it goes back to the while loop and continues asking for the input until it receives the correct input which in this case it can only be 1-9.

import string
string.ascii_letters
def player_choice(board):
    position = 0
    while position not in list(range(1,10)) or space_check(board, position) or position in list[string.ascii_letters]:
        if position in list[string.ascii_letters]:
            pass
        position = int(input("Please enter a position(1-9): "))
    return position

I tried importing ascii_letters from the string library to tell python that if the input is inside of the that list to go back to the while loop, but everytime I run the code i get a syntax error saying that the input only accepts an integer.

Does this answer your question? [How can I limit the user input to only integers in Python](https://stackoverflow.com/questions/23326099/how-can-i-limit-the-user-input-to-only-integers-in-python) — Pranav Hosangadi, Nov 20 '22 at 22:39
Or this one: https://stackoverflow.com/questions/23294658/asking-the-user-for-input-until-they-give-a-valid-response — Pranav Hosangadi, Nov 20 '22 at 22:40

puf · Answer 1 · 2022-11-21T19:02:17.487

1

First solution using simple checkings

def player_choice(board):
    while True:
        position = input("Please enter a position(1-9): ")
        if position.isdecimal() and len(position) == 1 and position != '0':
            position = int(position)
            break
    return position

Second solution using regex

import re

def player_choice(board):
    while True:
        position = input("Please enter a position(1-9): ")
        if re.match('^[1-9]$', position):
            position = int(position)
            break
    return position

edited Nov 21 '22 at 19:02

answered Nov 20 '22 at 23:17

puf

359
3
13

2

Are you aware that something like `'⑧'.isdigit()` yields `True`? The `⑧` is clearly not an integer value. – Matthias Nov 20 '22 at 23:41
@Matthias I didn't know that. Funny behavior ) – puf Nov 20 '22 at 23:44
@Matthias I will change to a `isdecimal()` – puf Nov 20 '22 at 23:51
Some months ago that was new for me too - after nearly 20 years of Python. – Matthias Nov 21 '22 at 11:41
1

Both these solutions accept `0` – Pranav Hosangadi Nov 21 '22 at 17:39
1

@PranavHosangadi my bad! Fixed them both – puf Nov 21 '22 at 19:04

score -2 · Answer 2 · answered Nov 20 '22 at 23:26

-2

Use typing.

def whatever(param: int):

answered Nov 20 '22 at 23:26

Lucas Vale

19
4

4

Unless you use an interpreter that enforces them, type **hints** are just that -- _hints!_. Even if you were to use such an interpreter, typing it as an integer does nothing to ensure that the value returned by `input` is actually a numeric value. – Pranav Hosangadi Nov 21 '22 at 06:43

Defining a function that only accepts an integer as an input

2 Answers2