Thread: Is program salvageable?

In 1990, I designed a small calculator-like program written for DOS. A friend, who has passed away, coded it in C++. I have the complete source code for it with these exceptions. Let me add I know absolutely nothing about C++ other than I can spell "compilor" (just kidding). I do know the source code contains only one *.h (header?) file which begins with

#include <stdio.h>
#include <cwuser.h>
#include <cwdos.h>
#include <cwform.h>
#include <cwarch.h>

The five files I do not have. I know the stdio.h file is available but I can find no reference to any of the "cw" files.

I want to upgrade my program to Windows interface (I hope you understand what I want to do since I don't know the correct terminology) and make some minor "label" like changes and perhaps, rearrange or remove certain modules, such as remove the "Length Calculator module" and the like.

Am I out of luck without those four files?

Thank you very very much for your expertise.