python 3.x上的列表索引超出范围错误

Question

error message:

Traceback (most recent call last): File "C:\\Users\\Name\\Desktop\\transpositioncipher.py", line 17, in cipher.append(stringList[(x*result)+i])

IndexError: list index out of range

I am making a Transposition Cipher to encrypt a string. I will be working on decryption later.

I have been running into this error with no luck of fixing it. The output should be [f, u, o, r] if the input text is 'four'.

import math

stringToEnc = input("String to encrypt: ")
stringList = list(stringToEnc.replace(" ", ""))
letterCount = len(stringList)

encrypted = []
result = letterCount

for i in range(2, int(math.sqrt(letterCount))+1):
        if letterCount % i == 0:
            result = i
            break
i = 0
while i != letterCount:
        for x in range(result):
                encrypted.append(stringList[(x*result)+i])
        i+=1

print(encrypted)

Answer 1

If you look in the debugger, or add print ((x*result) + i) into the while loop, you will see that print ((x*result) + i) returns 4 on the 3rd iteration of the for loop. 4 is out of bounds for stringList which has a length of 4, but only the indexes 0,1,2,3.