string/file manipulation simple

[jeff]

Hey,

first of all sorry if this has double posted my mail progie did some
funny stuff

I was just creating an encryption/ decryption program in python, ive
got no problem with the algothims or anything like that. my only
difficulty is how to i take a file and read in each charecter and then
preform and operation to it and then output it to another file,
basically i just wanna know how to take a string and then perform
actions to each charecter

cheers

greg