C++ code breaking homework

I've been given a homework task to write a simple decryption program in C++. Each letter of the alphabet was substituted for another letter in the text ([login to view URL] attached) and it was a one-to-one mapping. The full instructions are included (Instructions of Task [login to view URL] and Instructions of Task [login to view URL]) I need someone with experience in C++ programming to finish this project. I have included my unfinished program (my unfinished [login to view URL]), and two other (sort of) finished programs that I got from guys who did this project last year ([login to view URL] and [login to view URL]) I can't get either of these to successfully compile. If you can finish my program that would be really helpful. Feel free to adjust it as much as you see fit. I am using Bloodshed Software - Dev-C++ compiler.