fix me a little bug

i have a perfectly working project. but this project was written in visual studio environment , and i used there some libraries that the Ubuntu (Terminal) doesn't recognise. after that i found out that the requirement was that the project should be compiled in gcc compiler in Ubuntu/Linux (Terminal) and not in windows. the project is functioning 100% when executing in windows (visual studio) but it should be compiled in gcc compiler. VERY IMPORTANT NOTE : THE FIX SHOULD BE DONE WITH MINIMUM LINE OF CODE CHANGES TO THE CURRENT PROJECT. any help please ??!!