Best way to loop over a python string backwards

Question

What is the best way to loop over a python string backwards?

The following seems a little awkward for all the need of -1 offset:

string = "trick or treat" for i in range(len(string)-1, 0-1, -1):     print string[i] 

The following seems more succinct, but is it actually generate a reversed string so that there is a minor performance penalty?

string = "trick or treat" for c in string[::-1]:     print c 

Answer 1

Try the reversed builtin:

for c in reversed(string):      print c 

The reversed() call will make an iterator rather than copying the entire string.

PEP 322 details the motivation for reversed() and its advantages over other approaches.