如何在python中存储字符串变量并在函数中传递它们？

Question

I have a problem where i get an error message telling me its used before its assigned. I am not sure how to pass around the variable result and answer in my code. The problem is that i am creating a shift cypher.

These are the instructions:

Complete the encode method so that it returns the encoded message. Complete the decode method so that it returns the decoded message. In the main method, - prompt the user for the message. - prompt the user for the shift amount.
- Print the message.
- Call encode with the message and the shift amount.
- Store the encoded message returned from encode.
- Print the encoded message.
- Send the encoded message and the shift amount to the decode method.
- Print the decoded message.

def encode(s, shiftamount):
  for x in range(0, len(s)):

    if s[x] == " ":
      print(" ", end="")

    if s[x] in "ABCDEFGHIJKLMNOPQRSTUVWXYZ":
      if chr(ord(s[x]) + shiftamount) > 'Z' : 
        result += chr(ord(s[x]) + (shiftamount - 26)) 

      if chr(ord(s[x]) + shiftamount) <= 'Z' :
        result += chr(ord(s[x]) + shiftamount)

    if s[x] in "abcdefghijklmnopqrstuvwxyz":
      if chr(ord(s[x]) + shiftamount) > 'z' : 
        result += chr(ord(s[x]) + (shiftamount - 26)) 

      if chr(ord( s[x] ) + shiftamount) <= 'z' :
        result += chr(ord(s[x]) + shiftamount)
  return result

def decode(s, shiftamount):

  for y in range(0, len(s)):

    if s[y] == " ":
      print(" ", end="")

    if s[y] in "ABCDEFGHIJKLMNOPQRSTUVWXYZ":
      if chr(ord(s[y]) + shiftamount) > 'Z' : 
        answer += chr(ord(s[y]) - (shiftamount - 26)) 

      if chr(ord(s[y]) + shiftamount) <= 'Z' :
        answer += chr(ord(s[y]) - shiftamount)

    if s[y] in "abcdefghijklmnopqrstuvwxyz":
      if chr(ord(s[y]) + shiftamount) > 'z' : 
        answer += chr(ord(s[y]) - (shiftamount - 26)) 

      if chr(ord( s[y] ) + shiftamount) <= 'z' :
        answer += chr(ord(s[y]) - shiftamount)
  return answer


def main():
  s = input("Enter the message:")
  shiftamount = int(input("Enter the shift:"))
  print(s)
  encode(s,shiftamount)
  decode(s,shiftamount)
  print(result)
  print(answer)


########################################################################
###                Do not modify anything below here                 ###
########################################################################
if __name__ == '__main__':
      main()

Answer 1

You need to define the result and answer variables before using += operation, also in main you need to assign it to a local variable before printing.

Lines: 52,53,25,2

def encode(s, shiftamount):
  result=''
  for x in range(0, len(s)):

    if s[x] == " ":
      print(" ", end="")

    if s[x] in "ABCDEFGHIJKLMNOPQRSTUVWXYZ":
      if chr(ord(s[x]) + shiftamount) > 'Z' : 
        result += chr(ord(s[x]) + (shiftamount - 26)) 

      if chr(ord(s[x]) + shiftamount) <= 'Z' :
        result += chr(ord(s[x]) + shiftamount)

    if s[x] in "abcdefghijklmnopqrstuvwxyz":
      if chr(ord(s[x]) + shiftamount) > 'z' : 
        result += chr(ord(s[x]) + (shiftamount - 26)) 

      if chr(ord( s[x] ) + shiftamount) <= 'z' :
        result += chr(ord(s[x]) + shiftamount)
  return result

def decode(s, shiftamount):

  answer=''

  for y in range(0, len(s)):

    if s[y] == " ":
      print(" ", end="")

    if s[y] in "ABCDEFGHIJKLMNOPQRSTUVWXYZ":
      if chr(ord(s[y]) + shiftamount) > 'Z' : 
        answer += chr(ord(s[y]) - (shiftamount - 26)) 

      if chr(ord(s[y]) + shiftamount) <= 'Z' :
        answer += chr(ord(s[y]) - shiftamount)

    if s[y] in "abcdefghijklmnopqrstuvwxyz":
      if chr(ord(s[y]) + shiftamount) > 'z' : 
        answer += chr(ord(s[y]) - (shiftamount - 26)) 

      if chr(ord( s[y] ) + shiftamount) <= 'z' :
        answer += chr(ord(s[y]) - shiftamount)
  return answer


def main():
  s = input("Enter the message:")
  shiftamount = int(input("Enter the shift:"))
  print(s)
  result=encode(s,shiftamount)
  answer=decode(s,shiftamount)
  print(result)
  print(answer)


########################################################################
###                Do not modify anything below here                 ###
########################################################################
if __name__ == '__main__':
      main()

Answer 2

try this:

def main():
  s = input("Enter the message:")
  shiftamount = int(input("Enter the shift:"))
  print(s)
  e = encode(s,shiftamount)
  d = decode(s,shiftamount)
  print(e)
  print(d)

you need to create reference, and instantiate it