-Programming implementation of Caesar cipher. C++

You have to submit your source code and screen shots of outputs to get full credits. User will enter the plaintext and the encryption key. Your program will output the ciphertext. User will enter the ciphertext and your program will output the plaintext. You can use the following message as to test your program.(Then punctuation cannot ignored.)

Whenever you feel like criticizing any one, he told me, just remember that all the people in this world havent had the advantages that youve had.