What do I modify in the code in order for it to work in Python 2.7?

Question

 credit_num = input("Enter the credit card number: ").replace(" ", "") tot1 = 0 tot2 = 0 for i in credit_num[-1::-2]: tot1 += int(i) for i in credit_num[-2::-2]: tot2 += sum(int(x) for x in str(int(i)*2)) rem = (tot1 + tot2) % 10 if rem == 0: print("The entered numbers are valid.") else: print("The entered numbers are not valid.") 

This works in Python 3.5. What do I modify in order for it to work in Python 2.7?

Answer 1

Replace input() with raw_input() and change the print function calls to print statements or you can import print_function from __future__ as @BrenBarn suggests, eg:

from __future__ import division, print_function

credit_num = raw_input("Enter the credit card number: ").replace(" ", "")
tot1 = 0 
tot2 = 0 

for i in credit_num[-1::-2]:
    tot1 += int(i)

for i in credit_num[-2::-2]:
    tot2 += sum(int(x) for x in str(int(i)*2))

rem = (tot1 + tot2) % 10

if rem == 0:
    print("The entered numbers are valid.")
else:
    print("The entered numbers are not valid.")

Answer 2

If you want the same script to work in both Python 2.x and Python 3.x, I suggest using the "six" module and the following code. (Note that the first two added lines are the only change I've made.)

from __future__ import print_function
from six.moves import input

credit_num = input("Enter the credit card number: ").replace(" ", "")
tot1 = 0
tot2 = 0

for i in credit_num[-1::-2]:
    tot1 += int(i)

for i in credit_num[-2::-2]:
    tot2 += sum(int(x) for x in str(int(i)*2))

rem = (tot1 + tot2) % 10

if rem == 0:
    print("The entered numbers are valid.")
else:
    print("The entered numbers are not valid.")