For this lab we are going to be creating a basic encryption/decryption function

For this lab 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

and so on.... (you must go all the way to z == a)

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

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

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

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

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

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