How to check for palindrome using Python logic

Question

I'm trying to check for a palindrome with Python. The code I have is very for-loop intensive.

And it seems to me the biggest mistake people do when going from C to Python is trying to implement C logic using Python, which makes things run slowly, and it's just not making the most of the language.

I see on this website. Search for "C-style for", that Python doesn't have C-style for loops. Might be outdated, but I interpret it to mean Python has its own methods for this.

I've tried looking around, I can't find much up to date (Python 3) advice for this. How can I solve a palindrome challenge in Python, without using the for loop?

I've done this in C in class, but I want to do it in Python, on a personal basis. The problem is from the Euler Project, great site By the way,.

def isPalindrome(n):     lst = [int(n) for n in str(n)]     l=len(lst)     if l==0 || l==1:         return True     elif len(lst)%2==0:         for k in range (l)         #####     else:         while (k<=((l-1)/2)):             if (list[]):                 #####     for i in range (999, 100, -1):     for j in range (999,100, -1):         if isPalindrome(i*j):             print(i*j)             break 

I'm missing a lot of code here. The five hashes are just reminders for myself.

Concrete questions:

1. In C, I would make a for loop comparing index 0 to index max, and then index 0+1 with max-1, until something something. How to best do this in Python?

2. My for loop (in in range (999, 100, -1), is this a bad way to do it in Python?

3. Does anybody have any good advice, or good websites, or resources for people in my position? I'm not a programmer, I don't aspire to be one, I just want to learn enough so that when I write my bachelor's degree thesis (electrical engineering), I don't have to simultaneously LEARN an applicable programming language while trying to obtain good results in the project. "How to go from basic C to great application of Python", that sort of thing.

4. Any specific bits of code to make a great solution to this problem would also be appreciated, I need to learn good algorithms.. I am envisioning 3 situations. If the value is zero or single digit, if it is of odd length, and if it is of even length. I was planning to write for loops...

PS: The problem is: Find the highest value product of two 3 digit integers that is also a palindrome.

Answer 1

A pythonic way to determine if a given value is a palindrome:

str(n) == str(n)[::-1] 

Explanation:

• We're checking if the string representation of n equals the inverted string representation of n
• The [::-1] slice takes care of inverting the string
• After that, we compare for equality using ==

Answer 2

An alternative to the rather unintuitive [::-1] syntax is this:

>>> test = "abcba" >>> test == ''.join(reversed(test)) True 

The reversed function returns a reversed sequence of the characters in test.

''.join() joins those characters together again with nothing in between.