Caesar Cipher python with alphabet input

Question

I'm a beginner in python and taking a course on it. I've been tasked with making a caesar cipher where I can input the alphabet used. For this I can't use ord() or list() or any imported functions, only basic python. I've got it to work for one letter but I can't seem to figure out how to make it work for more than one letter. Any help would be greatly appreciated!

def cypher(target, alphabet, shift):
    
    for index in range( len(alphabet)):
        if alphabet[index] == target:
           x = index + shift
           y =  x % len(alphabet)
                  
    return (alphabet[y])

Answer 1

I see this is your first question. Thanks for asking.

I think what you want your code to encrypt a full length script using the function you built above. So, what your function does is it takes a letter as target and shifts it.

This can easily be applied to a string by iterating over its elements.

I have provided the correct implementation for your query with some tweaks here :

alphabet = "abcdefghijklmnopqrstuvwxyz"

def cypher(target, shift):
    for index in range(len(alphabet)):
        if alphabet[index] == target:
            x = index + shift
            y =  x % len(alphabet)
            return (alphabet[y])


string = "i am joe biden"
shift = 3 # Suppose we want to shift it for 3
encrypted_string = ''
for x in string:
    if x == ' ':
        encrypted_string += ' '
    else:
        encrypted_string += cypher(x, shift)

print(encrypted_string)

shift = -shift # Reverse the cypher
decrypted_string = ''
for x in encrypted_string:
    if x == ' ':
        decrypted_string += ' '
    else:
        decrypted_string += cypher(x, shift)

print(decrypted_string)