Access Keystrokes in C

Question

I am trying to access keystrokes in C. I can access alphanumeric keys. How can I access Control, Shift and Alt key?
Plus I read some

Answer 1

Dietrich Epp answered in a comment: use ncurses library.

See also this question

And you might make an X11 client graphical application; in that case use a graphical toolkit library like GTK or Qt

If you want to make a console application, use ncurses or perhaps readline

And your question, when taken literally, has no sense: the strict C standard don't know what a key or a keystroke is (the only I/O operations mentioned in the standard are related to thru FILE). This is why most people uses additional libraries and standards (in addition of those required by ISO C), eg. Posix...