C++ - Ceaser Shift + Railroad Decoding and Encoding

You are free to use the string class or C-Strings as you see fit . You must declare a minimum of two functions, one to encode and another to decode - You are free to declare more than two, but there must be at least one function that does encoding and at least one function that does decoding The message will be read in from a file The length of the message is arbitrary Th e message will be on a single line only The message must be converted to upper case - ONLY letters should be converted You will perform a Caesar shift, the size of which is specified when the program is executed The shift can only be a positive integer The highest allowable shift is 25 - ONLY letters will be shifted You will also perform a two layer rail fence cipher