Keyboard input/Obtain a Y or N response: Difference between revisions

=={{header|OCaml}}==

Unix library is normally bundled with any standard OCaml distribution for POSIX interfaces.

Interfacing with [https://en.wikipedia.org/wiki/POSIX_terminal_interface termios] is specific to UNIX-likes.

<lang OCaml>open Unix

type mode = Prompt | Input

let original_attrs = tcgetattr stdin

let set = function

| Prompt -> tcsetattr stdin TCSAFLUSH {original_attrs with c_icanon = false}

| Input -> tcsetattr stdin TCSAFLUSH original_attrs

let getchar buf =

if read stdin buf 0 1 = 0 then raise End_of_file

else Bytes.get buf 0</lang>

Main:

<lang OCaml>let _main =

let buf = Bytes.create 1 in

let rec prompt () =

print_string "Prompt? [Y/N]: ";

flush_all();

set Prompt;

match getchar buf with

| 'n'|'N' -> ();

| 'y'|'Y' -> print_endline ": Ok."; prompt ();

| _ -> print_endline ": Invalid."; prompt ();

set Input;

in

prompt ()</lang>