I made a program. I also made my own file type, which the program can create, open, and edit. In Explorer, I right clicked on this new file type and selected "Open With" and chose my program. Of course, it just opens the program without loading the file.
How do I let my program know that it's being requested to open a file on startup? Is there some command line argument that "Open With" sends?
Yes, Windows Explorer sends the path of the file as the command line argument to the executable of your application.
You could use
args[0]
in C# orargv[1]
in C++ to read it.