Python palindrome program not working

Question

I\'ve written a simple program in python which checks if the sentence is palindrome. But I can\'t figure out why isn\'t it working. The results is always False. Does anyone know

Answer 1

I presume this is an assignment and the recursion is necessary, obviously return word == word[::-1] is simpler but is not really relevant. You can write your recursive function a bit more succinctly:

def isPalindrome(word):
    if not word:
        return True
    return word[0] == word[-1] and isPalindrome(word[1:-1])

word[0] == word[-1] will either be True or False so you will either reach an empty string where not word will True so the recursion ends and the function returns True or word[0] == word[-1] will be False so the function will return False as and isPalindrome(word[1:-1]) will never be evaluated.

I would also maybe do the lowering outside of the function:

def isPalindrome(word):
    if not word:
        return True
    return word[0] == word[-1] and isPalindrome(word[1:-1])


sentence = input("Enter a sentence: \n")
sentence = sentence.strip().lower()
sentence = sentence.replace(" ", "")
if isPalindrome(sentence):
    print("The sentence %s is palindrome." % sentence)
else:
    print("The sentence %s is NOT palindrome" % sentence)