use X11/extensions/XTest.h
use X11/keysym.h

main()
	Display* display = XOpenDisplay(NULL)
	if display == NULL
		return 1
	XTestFakeKeyEvent(display, XKeysymToKeycode(display, XK_Num_Lock), True, CurrentTime)
	XTestFakeKeyEvent(display, XKeysymToKeycode(display, XK_Num_Lock), False, CurrentTime)
	XCloseDisplay(display)