What's the easiest way to validate a string is however many digits it needs to be and is all integers?

Question

I have to validate that the string is either 4 or 6 digits. The string cannot contain any characters, only integers. Return true if it meets the condition else false.

I tried to create a list with acceptable digits and loop through the string and compare. If any part of the string is not in the acceptable list I will exit the loop and return false. If the running total is equal to 4 or 6 then it should be true. python code:

def validate(n):
   count = 0
   valid_list = list(range(10))
   for digit in pin:
      if digit not in valid_list:
         return False
      count += 1

I'm not sure why something like 1234 is being returned as False.

Answer 1

How about with regex?

import re
str="03506"
pattern="[0-9]{4,6}"
prog=re.compile(pattern)
result=prog.match(str)    
if result:
    return True
else:
    return False

This matches digits that are between 4 and 6 characters long. If you mean you want to match those string that are 4 or 6 long, you can try

import re
str="03506"
pattern1="[0-9]{4}"
pattern2="[0-9]{6}"

if re.match(pattern1,str) or re.match(pattern2, str):
    return True
else:
    return False