Question

I have made a program in Python 3, which tests whether a number is a palindrome. Obviously it is not done, but when I try to run it:

#!/usr/bin/env python
def testforpalin():
    i = 101
    lop = list(str(i))
    print(lop)
    len(lop)
    if lop[0] == lop[len-1]:
        print("hi")
testforpalin()

TypeError: unsupported operand type(s) for -: 'builtin_function_or_method' and 'int'

I get that error. How do I fix this?

Answer 1

in the line

if lop[0] == lop[len-1]:

you have len-1 where len is the function that gives you the length of the string (hence the error – you are trying to do subtraction where one of the values is len which is a “builtin_function_or_method”). you probably mean lop[len(lop)-1] (which would work), but it would be simpler to do:

if lop[0] == lop[-1]:

because [-1] gives you the last element in a string or array (and [-2] gives you next-to-last, etc).