Need help making file i/o program using Python

Question

Make a Cryptography program as follows.(Add file i/o to it)

1. You should have (at least) two functions: encrypt and decrypt.
2. Enhance your main routine to: a. welcome the user
   b. ask the user whether (s)he wants to encrypt or decrypt
   c. ask the user what file the encrypted message is to be written to/read from
   d. if encrypting:
   ask for the message to encrypting
   ask for the key
   call encrypt to create cipher text
   open the file
   write the cipher test to the file
   close the file
   inform the user that the cipher text (displayed) has been stored to the file (make sure to mention the file's name!)
   e. if decrypting: ask for the key open the file read the cipher test from the file close the file call decrypt to decipher the cipher text display the message for the user
   f. ask if the user would like to perform another task
   g. if so, go to (b)
   h. otherwise quit

Here are the codes I need to add in the program:

#open file to write record(s). It will create the file if new!
f = open("temp.txt", "w") 
f.write("Hello!\n")
f.close

#open file to read this time
f = open("temp.txt", "r")
line = f.readline()
print(line)
f.close

#try binary read...
f = open("temp.txt", "rb")
line = f.readlines()
print(line)
f.close

Here is what I have already (Everything but the input/output functions for the files):

# Caesar Cipher

MAX_KEY_SIZE = 26

def getMode():
    while True:
        mode = input("Do you wish to encrypt or decrypt a message?").lower()
        if mode in "encrypt e decrypt d". split():
            return mode
        else:
##            print("Enter either "encrypt" or "e" or "decrypt" or "d".')
def getMessage():
    return input("Enter you message")

def getKey():
    key = 0
    while True
        key = int(input("Enter a key number (1-26)"))
        if (key >=1 and key <= MAX_KEY_SIZE):
            return key

def getTranslatatedMessage(mode, messafe, key):
    if mode[0] == "d":
        key = -key
    translated = ""

    for symbol in message:
        if symbol.isalpha():
            num = ord(symbol)
            num += key

            if symbol.isupport():
                if num > ord("Z"):
                  num -= 26
                elif num < ord("A"):
                  num += 26
            elif symbol.islower():
                if num < ord("z"):
                  num += 26
                elif num < ord("a"):
                  num += 26

            translated += chr(num)
        else:
            translated += symbol
    return translated
mode = getMode()
message = getMessage()
key = getKey()

My question is where do I add the above codes into the encrypt/decrypt program?

Answer 1

It seems you want to proceed a file instead of a message provided by the user. So in getMessage you should return the content of the read file

    def getMessage():
        f = open("temp.txt", "r")
        text = f.read()
        f.close()
        return text

And you write to file the translated message.

Answer 2

You didn't ask your question.

You can find informations about input/output in Python documentation

Basically, you can open a file, write into it and close it as following:

    f = open("myfile", "w")
    text = "something"
    f.write(text)
    f.close()

To deal with binary data it is possible to specify binary format "wb" for writing or "rb" for reading and conversions like:

    f = open("binfile", "rb")
    buffer = f.read(2)
    print hex(ord(buffer[0]))

There are other ways to pack/unpack binary files in Python but you must ask a more precise question.