recursion function

Question

con anyone explain to my why this function did not work

def isPalindrome(str, first=0, last=-1):
if first >= len(str)/2:
return True
if str[first] != str[last]:
return False
isPalindrome(l, first+1, last-1)

l am try to use the recursion function to know if the string is palindrome or not

Answer 1

https://code.sololearn.com/cW0Ly3HBUi5n/?ref=app

1. The variable l doesn't exist, you're meant to pass str as the argument.
2. You have to put a return before the recursive function call.

Answer 2

Angelo Yeah I assume it's only for practice, I myself understand how recursion works but I try to stay away from them as far as possible. Checking if something is a palindrome is as simple as this:

def isPalindrome(x):
return x == x[::-1]

Answer 3

This is sooo wrong...
Just the fact you want to do it recursively is wrong (all that poor stack memory wasted)

First: isPalindrome("abcd... ", 3) will return True when it's not supposed to

Second: you should at least return the function in some way to make it recursive

So...

if first >= last: return True
if str[first] != str[last]:
return False
return isPalindrome(str, first+1, last-1)

Answer 4

That, inxanedev!, is a Python code worth of that name!