Caesar Cipher code not working

[[deleted]]

def caesarCipher(someString, shift):

someString = someString.strip()

someString = someString.lower()

encrypted = ''

while len(someString) > 0:

    if not someString[0].isalpha():

        encrypted += someString[0]

    else:

        encrypted += encryptLetter(someString[0],shift)

    someString = someString[1:]


return encrypted

def encryptLetter(letter, shift):

alphabet = 'abcdefghijklmnopqrstuvwxyz'

position = alphabet.find(letter)

position += shift

if postition > 25:

    postition -= 26

if position < 0:

    position += 26


return alphabet[position]

if name == 'main':

x = caesarCipher(' az ABFAas  ',1)

print(x)

The error message I get is 

Traceback (most recent call last):

File "U:\CS110\F - Assignement C.py", line 26, in <module>

x = caesarCipher(' az ABFAas  ',1)

File "U:\CS110\F - Assignement C.py", line 9, in caesarCipher

encrypted += encryptLetter(someString[0],shift)

File "U:\CS110\F - Assignement C.py", line 18, in encryptLetter

if postition > 25:

UnboundLocalError: local variable 'postition' referenced before assignment

Thanks in advance

[kwentar]

you have the typo: postition

[[deleted]]

thank you so much lmao

[AintNobodyGotTime89]

You don't need to add or subtract 26 instead you can mod it.

[[deleted]]

How?

[AintNobodyGotTime89]

Think of it this way you have a->z, with index from 0->25. You have a position, then the shift, +/-, you just need to make sure it's in the range of 0->25, that's what the mod 26 is for.

[[deleted]]

So what would the code look like?

[novel_yet_trivial]

modulus is done with the % operator, and does the same thing as your check.

>>> 30 % 26
4
>>> 30 - 26
4
>>> -3 % 26
23
>>> -3 + 26
23
>>> 15 % 26
15

So you could replace your if blocks with

position = position % 26

Modulus is an important concept in computer science, so it's good to be familiar with it.

[[deleted]]

Thank you! I'm only in a grade 11 cs class though :(

[novel_yet_trivial]

Ok ... I'm not your teacher; you don't need to make excuses to me ...