I figured out a constant:
#define CTRL 1-'a'
That way, if I write:
CTRL + 'a'
is the ASCII value of that key combination (CTRL here is that 1-'a' constant)
This I figured out from those lower un-printable ASCII characters that are displayed with that '^' symbol and a letter.
Emacs uses the Meta key for many commands (which is Alt on most keyboards), and I thought it would be cool if I can use that key in my programs.
I wonder how to do that with the Meta/Alt key?