You can create a simple form of encryption using the xor Boolean operator. For example, if you want to encrypt the letter 'A': (Without the use of Arrays)

1. Choose another letter as a "key", say 'X'
2. Encrypt 'A' with the xor function: encrypted = 'A' xor 'X'
3. Now you can decrypt by xor'ing your encrypted value with 'X' again: decrypted = encrypted xor 'X'

Write a C++ program that meets the following requirements:

1. Asks the user for the name of an input file and a "key" character
2. Encrypts each character in the file using the entered key and the xor function. (Note: The program should handle all standard alphanumeric characters.)
3. Your program should save the results of the encryption into a new file with the same base name, but with a ".xor" file extension.
4. Program should also provide an option to decrypt a given file.