Question: Prepare a modification of the encryption program of 15.5 whose transform function uses an integer key to transform the character passed to it.

The function transforms the character by adding the key to it. The key should be represented as a member of the Encryption class, and the class should be modified so that it has a member function that sets the encryption key.

When the program runs, the basic function should ask the user for the input file, the output file, and an encryption key.

Show that with these modifications, the same program can be used for both encryption and decryption the key should be presented as member of the encryption class

You have to modify the encryption program.