When you open a file in Vim, it creates filename.swp and stores unsaved changes there while the editor is running. If you close your SSH client without saving first (or if Vim, your SSH or your computer crash), your unsaved changes will remain in this file and can be recovered.
Note: you should save and quit vim before using p_copy or I will get your .swp file along with your program. This generally isn't a problem as the program as you last saved it will be in your C file. I will ignore your swap if present.
If Vim has actually crashed with unsaved work and left a .swp file behind, every time you open that file in Vim you'll get an ATTENTION message. You have a few options to choose from in this case. Generally you will choose either option E or R.
Option R will recover the unsaved work. Review it and if everything looks as it should, save and quit immediately, then start Vim again and choose option D to delete the swap. From here Vim will work normally again.
If you choose option E, Vim will ignore the recovery file and show you the last work you saved normally. If you do not want to recover, then save and quit, restart Vim and use option D to delete the swap file just as in the above case.
If you're not sure what to do or would like to decide later, options Q and A will quit without taking any action. You can also quit without saving if you'd like a chance to try both options E and R before deciding which to save.
If you had already chosen option E one or more times and saved new work without deleting the old swap, it would be a bad idea to recover. In that case, just use option D to remove the swap.
If you don't delete the old swap and begin editing, vim creates a new swap with extension .swo. If it crashes againthat will get left behind and this process may repeat causing multiple orphaned swap files. If you find this has happened and aren't sure what to do, please contact me for assistance.