[Solved] As a beginner in python, I tried to solve THE SPY LIFE problem. Can anybody say what is wrong in my code?

Question

msg = input()
smsg = reversed(msg)

valid = 'abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ'

valist = list(valid)
li = list(smsg)

for l in li:
if l in valist:
continue
else:
li.remove(l)

smsg = "".join(li)
print(smsg)

INPUT (case 2) :
t`a=e+r8g 9e78r3a4 u^o%y*

Expected output:
you are great

My output:
you ar7e great

Answer 1

when you iterate a list, and modify it, you continue iteration with the new list but with the old index...

so in case of your example, you start at index 0 and you remove *, so now at index 0 is y... on next iteration you read index 1, wich is not the next initial char (y) but %...

add a print statement inside your loop to view wich char is in l at each step ;)

as a fix, you could iterate on a copy of the list, so modification of original will not affect char iterations:

for l in li[:]:

another way would be to use string, wich are imutable, and build a new string by concatenating valid char... in this case, to reverse the string, you could use msg[::-1], as reversed() return a list (your list(smsg) is pointless ;P) or keep a list to iterate, without copying it as you don't modify it (by building a new string instead)

Answer 2

Aysha providing another solution rather than correcting OP code would confuse him (all the more by introducing regular expressions) and not help him to understand what he missed in its solution ^^

Answer 3

Try it using this way
import re

str_ = input()

pattern = r"[^A-Za-z ]"
newstr = re.sub(pattern, "", str_)
print(newstr[::-1])

Answer 4

visph Thank you so much bro. I understood what is wrong in my code.

Answer 5

Really Sorry visph and Subashini G I will never do it once again by giving another solution. I just showed him simplest way to solve this problem.

Answer 6

Aysha that seems simpler way to you as you are aware of regular expression, but for a beginner it would be cryptic to understand, and not help him to acquire basics of languages ;)

anyway, if OP is lazy, he would prefer copy pasting your answer rather than read my longer post and correct himself its solution ^^

Answer 7

happy to see you're not one of the lazy people wich prefer earning xp easily rather than really learning \o/

Answer 8

Here are two short-code possibilities:

#1
import re
print(re.sub("[^A-Za-z ]", "", input())[::-1])

#2
[print(x, end="") for x in input()[::-1] if x.isalpha()]

# Hope this helps