we are going to be creating a basic encryption/decryption function. The principle function we are writing will call an encrypt function and/or a decrypt function. Normally, I wouldn't spec the additional functions for you to write but for this lab I'm listing at least 3 functions you need to write. Our encryption is going to be basic. If a letter is simply going to be replaced with a different letter from the alphabet. Use this scheme when encrypting or decrypting:

a == z b == y c == x d == w e == v f == u g == t h == s i == r j == q k == p l == o m == n

So an 'a' will be come 'z' and a 'z' will become an 'a', a 'b' will become an 'y' and an 'y' will be come a 'b', and so on. We'll only be dealing with lower case letters. Any thing that isn't a lower case letter just gets "added" to the results string. So spaces stay spaces, punctuation stays punctuation, etc.

Here's a snippet of code you can use to start that process:

string results = "";
for ( int i=0; i<input.length(); i++ )
{
    if ( input[i] == 'a' )
    {
        results = results + "z";
    }

Requirements

You must write your method signatures in a file called: encrypt.h

You must write the principle function with signature: void encryptDecrypt( string inputfile, string outputfile );

You must write the "helper" function with signature: string encrypt( string input );

You must write the "helper" function with signature: string decrypt( string input );

Since my code needs to call your helper functions too, they must be declared in the header file too.

This is in c++, and I just need a basic code following these exact requirements.