how can i make an input in python that only accepts capitalized letters and numbers

Question

basically i need to get a variable as a user input (ch) that can only contain capitalized letters and numbers in form of a string of course . i tried to capitalize the input of the user even if he gave them in a lowercase format which worked fine but now i have to make sure he didn't use any signs (like what you see in forbidenCh) but my idea did not work pls help me out here you can use any methode you want as long as it accomplish's the purpose of the program and thnx

this is my attempt :

ch=str(input("only give letters and numbers"))
ch= ch.upper()
forbidenCh="!#$%&'()*+,-./:;<=>?@[\]^_`{|}~"
for i in forbidenCh:
 for j in ch:
   if i == j:
     ch=str(input("u didn't put captilized letters and numbers !!"))
     ch= ch.upper()
   else:
     break

Does this answer your question? [Regex pattern for capital letters and numbers only, with possible 'List'](https://stackoverflow.com/questions/6290173/regex-pattern-for-capital-letters-and-numbers-only-with-possible-list) — ombk, Nov 29 '20 at 13:23
https://stackoverflow.com/questions/6290173/regex-pattern-for-capital-letters-and-numbers-only-with-possible-list duplicate — ombk, Nov 29 '20 at 13:23

score 1 · Answer 1 · answered Nov 29 '20 at 13:26

1

Probably it might be easier to check for allowed characters only:

import string
allowedCharacters = string.digits + string.ascii_uppercase
# allowedCharacters >> 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ

ch = str(input("only give letters and numbers"))
ch = ch.upper()

# check if all characters of the input are in allowedCharacters!
if not all(c in allowedCharacters for c in ch):
    print("u didn't put captilized letters and numbers !!")
else:
    print("input is fine")

answered Nov 29 '20 at 13:26

Maurice Meyer

17,279
4
30
47

Also a good idea making `allowedCharacters` a set so that membership check is cheap – Pranav Hosangadi Nov 29 '20 at 13:35
@MEMER: The issue with exclude lists is always, that people forget things. In your list there a `whitespaces` and `°` missing at least and there might be a lot more. – Maurice Meyer Nov 29 '20 at 13:39

score 0 · Answer 2 · answered Nov 29 '20 at 13:27

0

you can do:

ch=str(input("only give letters and numbers"))
ch= ch.upper()
forbidenCh="!#$%&'()*+,-./:;<=>?@[\]^_`{|}~"
for i in forbidenCh:
 if i in ch:
   ch=str(input("u didn't put captilized letters and numbers !!"))
   ch= ch.upper()

answered Nov 29 '20 at 13:27

J3rry

11
2

fat mitchel 38 · Accepted Answer · 2020-11-29T14:29:22.020

0

ch = str(input("only give letters and numbers: "))
ch = ch.upper()
forbidden_chars = "!#$%&'()*+,-./:;<=>?@[\]^_`{|}~"
# enter for-loop
for forbidden_chars in ch:
    # checking if forbidden_chars is in user input, if true ask for 
    # new input
    if forbidden_chars in ch:
        ch = str(input("u didn't put capitalized letters and numbers!: "))
        ch = ch.upper()
    else:
        break

edited Nov 29 '20 at 14:29

answered Nov 29 '20 at 13:29

fat mitchel 38

54
4

2

as a a tip please explain what your code is doing so when other users arrive here looking for the same answer they can also understand it – Montresor Nov 29 '20 at 13:49

a121 · Answer 4 · 2020-11-29T13:40:47.190

0

for such questions using ascii values is easier and efficient.

check this out

code:

n=input("enter a valid string")
for i in n:
    if ord(i) in range(65,91) or ord(i) in range(48,58):
        pass
    else:
        print("invalid")
        break

how can i make an input in python that only accepts capitalized letters and numbers

4 Answers4