|GPC_MAIN() is a macro that you should use in place of the usual
main() C function since then your program will also work in GraphiC/Win.
In GraphiC/Win, GraphiC must provide the main() routine to set up
the message loop and initialize the GraphiC window. In GUI environments,
there are usually no command-line parameters since user input is obtained
through the menuing system or via prompt boxes. However, the usual argc
and argv arguments can be used in all environments if your program
is started from the command line.