FilesExpand file tree

 master

/

palindrome.py

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

46 lines (35 loc) · 1.21 KB

 master

/

palindrome.py

Copy path

Top

File metadata and controls

• Code
• Blame

46 lines (35 loc) · 1.21 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

#!/usr/bin/python3

"""

Asks for user input and tells if string is palindrome or not

Allowed characters: alphabets and punctuations .,;:'"-!?

Minimum alphabets: 3 and cannot be all same

Informs if input is invalid and asks user for input again

"""

import re

def is_palindrome(usr_ip):

"""

Checks if string is a palindrome

ValueError: if string is invalid

Returns True if palindrome, False otherwise

"""

# remove punctuations & whitespace and change to all lowercase

ip_str = re.sub(r'[\s.;:,\'"!?-]', r'', usr_ip).lower()

if re.search(r'[^a-zA-Z]', ip_str):

raise ValueError("Characters other than alphabets and punctuations")

elif len(ip_str) < 3:

raise ValueError("Less than 3 alphabets")

else:

return ip_str == ip_str[::-1] and not re.search(r'^(.)\1+$', ip_str)

def main():

while True:

try:

usr_ip = input("Enter a palindrome: ")

if is_palindrome(usr_ip):

print("{} is a palindrome".format(usr_ip))

else:

print("{} is NOT a palindrome".format(usr_ip))

break

except ValueError as e:

print('Error: ' + str(e))

if __name__ == "__main__":

main()