Caesar's Code

alphabet = "abcdefghijklmnopqrstuvwxyz"
numbers = "1234567890"
word = input("Enter the word you want me to cipher: ")
offset = int(input("Enter offset (must be an integer): "))

try:
    print()
    print("Before ciphering: " + word)
    list = []                                          # There, I will add the characters of the converted word


    for ch in word:                                    # 1st scan: ch = each character of the variable "word"\
        counter = 0                                             # Create a counter: it will be used to count the FAILS in the
                                                                # comparison between the "ch" and all the letters in "alphabet"
        for i in range(len(alphabet)):                 # 2nd scan: i = index in string "alphabet"

            if ch.lower() == alphabet[i]:              # Here, I see if "ch" converted to lowerCase is equal to alphabet[i]

                if ch == ch.lower():                                                 # If "ch" is lowerCase,
                    list.append(alphabet[(i + offset) % (len(alphabet))])            #I add the appropriate letter in list
                    break
                else:                                                               # If "ch" is upperCase,
                    letter = alphabet[(i + offset) % (len(alphabet))]               #I add the "letter" ("letter" is lowerCase) after I convert it into upperCase
                    list.append(letter.upper())
                    break

            elif i <= len(numbers)-1 and ch == numbers[i]:                          # If "ch" = numbers[i] and i <= 9 (avoid overflow)
                list.append(numbers[ (i + offset) % len(numbers) ])
                break

            elif ch == " ":                             # This is the case, when I find a "spacebar" character
                list.append(" ")                        # Malista, edw ekteleitai MONO mia fora h 2h for
                break

            else:                                       # Here, the 2nd loop goes, when "ch" !=  alphabet[i] and "ch" != " "
                counter += 1                            # I increase by 1 the counter in case of failure in comparison between ch and alphabet[i] or spacebar

        if counter == len(alphabet):                    # Gia na ftasei edw shmainei oti **DEN EGINE KANENA BREAK** kai episis o **counter = 26**, ara 26 failures ---> o "ch" einai kapoios allos character
            list.append(ch)

    print("After  ciphering: " + ''.join(map(str, list)))

except ValueError:
    print("Value Error!")