caesar_cipher.py

import art
print(art.logo)
alphabet = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']





#create a function 'encrypt()' that takes the original message and shift it.
# def encrypt(original_text,shift_amount):
#       cipher_text = ""
#       for letter in original_text:
            
#             shifted_position= alphabet.index(letter) + shift_amount
#             shifted_position %= len(alphabet) #0-25
#             cipher_text += alphabet[shifted_position]
            
#       print(f"Here is the encoded result: {cipher_text}")

#now, create a function 'decrypt()' for decrypting the message
# def decrypt(original_text,shift_amount):
#       output_text = ""
#       for letter in original_text:
            
#             shifted_position= alphabet.index(letter) - shift_amount
#             shifted_position %= len(alphabet) #0-25
#             output_text += alphabet[shifted_position]
            
#       print(f"Here is the encoded result: {output_text}")
            
def caesar(original_text,shift_amount,encode_or_decode):
      output_text = ""
      if encode_or_decode == "decode":
            shift_amount *= -1
      for letter in original_text:
            if letter not in alphabet:
                  output_text += letter
            else:
                  shifted_position= alphabet.index(letter) + shift_amount
                  shifted_position %= len(alphabet) #0-25
                  output_text += alphabet[shifted_position]
            
      print(f"Here is the {encode_or_decode}d result: {output_text}")
      
      
should_continue = True

while should_continue:      
      direction = input("Type 'encode' to encrypt, type 'decode' to decrypt:\n").lower()     
      text = input("Type your message:\n").lower()
      shift = int(input("Type the shift number:\n"))
      caesar(original_text=text,shift_amount=shift,encode_or_decode=direction)
      restart = input("Type 'yes' if you want to go again. Otherwise, type 'no'.\n").lower()

      
      if restart == 'no':
            should_continue = False
            print("Goodbye")