Vigenere Cipher no error message Python

Here is the code for the Vigenere Cipher:

BASE = ord("A") #65
print("Welcome to the keyword encrypter and decrypter!")
msg = ("FUN")
keyword = ("RUN")
list_out = []

for letter in msg:
    a = (ord(letter) - (BASE)) #67 - 65 = 2

for character in keyword:
    b = (ord(character) - (BASE)) #72 - 65 = 7
    list_out.append(BASE + a + b) #65 + 2 + 7 = 74
("".join(str(list_out)))

I am trying to get the each letter from the message and the keywords to individually be taken away from 65, which is the BASE. Then at the end I want the BASE to be added to the results from a and b. I want the new letter appended to the list and printed. If anyone can help, it will be much appreciated.

Above I stated how the program should work however I am not sure what the problem/problems are. The main problem with my code is that nothing is being printed.

Solution

You call join on the list to join the contents, not str(list), you are casting the list itself to a str and calling join on that, not the actual list.

You need to map each int to a str in your case.

"".join(map(str,list_out))

Which is equivalent to "".join([str(x) for x in list_out ])

If you want to change the ord's to chars you can map to chr:

"".join(map(chr,(list_out)))

Which can all be done in a single comprehension:

print("".join([chr(BASE + a + (ord(ch) - (BASE))) for ch in keyword)])

You are also only using the last value for a in the previous loop as you are assigning a new value each iteration depending on what that is supposed to be doing you may need += or nested loops:

for letter in msg:
    # will be equal to  (ord(N) - (BASE))
    a = (ord(letter) - (BASE)) #67 - 65 = 2