Keyboard input/Obtain a Y or N response: Difference between revisions
Keyboard input/Obtain a Y or N response (view source)
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{{
[[Category:Simple]]
[[user input::task| ]]
;Task:
Obtain a valid '''Y''' or '''N''' response from the [[input device::keyboard]].
The keyboard should be flushed, so that any outstanding key-presses are removed, preventing any existing '''Y''' or '''N''' key-press from being evaluated.
The response should be obtained as soon as '''Y''' or '''N''' are pressed, and there should be no need to press an enter key.
<br><br>
=={{header|8080 Assembly}}==
This program uses CP/M to read the keyboard.
<syntaxhighlight lang="8080asm">rawio: equ 6 ; Raw console input
puts: equ 9 ; String output
bdos: equ 5 ; CP/M entry point
org 100h
jmp demo
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Routine: read 'Y' or 'N' from the keyboard.
;;; Output: carry flag clear if Y pressed, set if N pressed.
yesno: mvi c,rawio ; Read input from console
mvi e,-1
call bdos
ana a ; Read keys as long as a key is pressed
jnz yesno ; (wait until keyboard is clear)
yread: mvi c,rawio ; Then, wait for a key to be pressed
mvi e,-1
call bdos
ana a
jz yread
ori 32 ; Set bit 5 to make input letters lowercase
cpi 'y' ; If the key is Y,
rz ; then return (carry is clear here)
cpi 'n' ; If the key is N,
stc ; then set the carry flag and return
rz
jmp yread ; If it wasn't Y or N, get another key
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Demo code: use the routine to read Y or N, and then print
;;; 'yes' or 'no'.
demo: call yesno ; Read Y or N
mvi c,puts
lxi d,yes
jnc bdos ; If carry clear, print 'Yes'
lxi d,no
jmp bdos ; Otherwise, print 'No'
yes: db 'Yes$'
no: db 'No$'</syntaxhighlight>
=={{header|8086 Assembly}}==
{{works with|MS-DOS}}
;Assembled using UASM v2.49
<syntaxhighlight lang="asm"> .model small
.stack 1024
.data
;no data needed
.code
start:
mov ax,@code
mov ds,ax
call PRIMM
BYTE "Exit program and return to MS-DOS? (Y/N)",0
mov ax,0C00h
int 21h ;flush keyboard buffer
forever:
call waitKey
;returns ASCII code in AL
and AL,11011111b ;ignore case
cmp al,"Y"
jz ReturnToMSDOS
cmp al,"N"
jz forever
;normally this would jump somewhere else but for simplicity it will wait
;for a yes response.
jnz forever
ReturnToMSDOS:
mov ax,0C00h
int 21h ;flush keyboard buffer
mov ax,4C00h
int 21h ;end program
;-------------------------------------------------------------------
; SUBROUTINES
;-------------------------------------------------------------------
waitKey:
mov ah,01h
int 16h
jz waitKey
ret
;waits until a key is pressed.
;return:
; AL = ASCII CODE
; AH = SCAN CODE (???)
;-------------------------------------------------------------------
PrintString: ;Print null-terminated strings
;input: string address = ds:si
lodsb ;Load a letter
cmp al,0 ;Was that letter the terminator?
jz PrintString_Done ;Yes? then RET
call PrintChar ;Print to screen
jmp PrintString ;Repeat
PrintString_Done:
ret
;-------------------------------------------------------------------
PrintChar:
push ax
mov ah,0Eh
int 10h ;print AL to the screen.
pop ax
ret
;-------------------------------------------------------------------
PrintSpace:
mov al,' '
jmp PrintChar ;JMP avoids a tail call.
;ret ;"PrintChar"'s ret will do this for us.
;-------------------------------------------------------------------
NewLine:
push dx
push ax
mov ah, 02h
mov dl, 13 ;CR
int 21h
mov dl, 10 ;LF
int 21h
pop ax
pop dx
ret
;-------------------------------------------------------------------
PRIMM:
pop si
push ax
;get return address in si, this is the source offset for
;the string that will be printed.
;String must be null terminated.
call PrintString
pop ax
push si
;PrintString adjusts the return address for us, it is now
;just after the null terminator. So put it back on the stack.
ret
;-------------------------------------------------------------------
end start</syntaxhighlight>
=={{header|8th}}==
<syntaxhighlight lang="forth">
\ get a yes or no response from the keyboard
: yes-no
con:key $20 bor
dup 'y n:= if ;; then
dup 'n n:= if ;; then
drop yes-no ;
: no? 'n n:= if "No" else "Yes" then . ;
"Yes or no? " con:print yes-no no?
cr bye
</syntaxhighlight>
=={{header|Action!}}==
<syntaxhighlight lang="action!">PROC MAIN()
Byte Key=764
Printe("Press Y or N to continue")
key=255
Do
Until Key=43 or Key=35
Od
Print("You pressed ")
If Key=43 then Printe("Yes") Fi
If Key=35 then Printe("No ") Fi
RETURN</syntaxhighlight>
=={{header|Ada}}==
<syntaxhighlight lang="ada"> function Yes_Or_No (Prompt : String := "Your answer (Y/N): ") return Boolean is
Answer : Character;
begin
Ada.Text_IO.Put (Prompt);
loop
Ada.Text_IO.Get_Immediate (Answer);
case Answer is
when 'Y'|'y' => return True;
when 'N'|'n' => return False;
when others => null;
end case;
end loop;
end Yes_Or_No;</syntaxhighlight>
=={{header|AutoHotkey}}==
<syntaxhighlight lang="autohotkey">Loop, {
Input, Key, L1
if (Key = "n" || Key = "y")
break
}
MsgBox, % "The response was """ Key """."
ExitApp</syntaxhighlight>
=={{header|AWK}}==
<syntaxhighlight lang="awk">
# syntax: GAWK -f KEYBOARD_INPUT_OBTAIN_A_Y_OR_N_RESPONSE.AWK
BEGIN {
printf("you entered %s\n",prompt_user())
exit(0)
}
function prompt_user( rec) {
# AWK lacks the ability to get keyboard input without pressing the enter key.
while (1) {
printf("enter Y or N ")
getline rec <"con"
gsub(/ /,"",rec) # optional
if (rec ~ /^[nyNY]$/) {
break
}
}
return(rec)
}
</syntaxhighlight>
{{out}}
<pre>
enter Y or N y
you entered y
</pre>
=={{header|Axe}}==
Since the TI-83/84 require a modifier key to access the letters, this example uses the 2nd key as Y and the Clear key as N.
<syntaxhighlight lang="axe">While getKey(0)
End
While 1
If getKey(15)
Disp "N",i
Return
ElseIf getKey(54)
Disp "Y",i
Return
End
End</syntaxhighlight>
=={{header|BASIC}}==
==={{header|Applesoft BASIC}}===
<syntaxhighlight lang="applesoftbasic">10 LET C = PEEK (49168): REM CLEAR KEYBOARD
20 PRINT "PRESS Y OR N TO CONTINUE"
30 GET K$
40 IF K$ < > "Y" AND K$ < > "N" THEN 30
50 PRINT "THE RESPONSE WAS ";K$
</syntaxhighlight>
==={{header|BASIC256}}===
<syntaxhighlight lang="freebasic">print "Do you want to continue y/n : ";
do
KBD$ = key
until KBD$ = "89" or KBD$ = "78"
print chr(KBD$)
if KBD$ = "89" then
print "OK, continuing"
else
print "OK, finishing"
end if</syntaxhighlight>
==={{header|QBasic}}===
<syntaxhighlight lang="qbasic">PRINT "Press Y or N to continue."
DO
KBD$ = ""
WHILE KBD$ = ""
KBD$ = UCASE$(INKEY$)
WEND
IF KBD$ <> "Y" AND KBD$ <> "N" THEN BEEP
LOOP UNTIL KBD$ = "Y" OR KBD$ = "N"
PRINT "The response was "; KBD$</syntaxhighlight>
==={{header|BBC BASIC}}===
<syntaxhighlight lang="bbcbasic"> REPEAT UNTIL INKEY$(0) = ""
PRINT "Press Y or N to continue"
REPEAT
key$ = GET$
UNTIL key$="Y" OR key$="N"
PRINT "The response was " key$</syntaxhighlight>
==={{header|Commodore BASIC}}===
<syntaxhighlight lang="basic">10 PRINT "PRESS Y OR N TO CONTINUE:";
20 POKE 198, 0: REM CLEAR KEY BUFFER
30 GET K$
40 IF K$ <> "Y" AND K$ <> "N" THEN 30
50 PRINT K$</syntaxhighlight>
Note that 198 is the location of the keyboard buffer index on the VIC-20, C-64, and C-128. On the PET, the correct location is 158, while on the Plus/4 and C-16, it's 239.
The loop on lines 30 - 40 will cycle as fast as the interpreter can go, assigning K$ the empty string until the user presses a key. On versions of BASIC later than the 2.0 on the VIC and 64 (e.g. 3.5 on the C-16 and Plus/4, 7.0 on the C-128), GETKEY may be used in place of GET. GETKEY will wait for the user to press a key before continuing, so the polling is done in the BASIC interpreter's machine language code, and the BASIC loop only cycles when the user presses a key other than Y or N.
==={{header|GW-BASIC}}===
{{works with|QBasic}}
<syntaxhighlight lang="gwbasic">10 CLS: PRINT "Press Y or N to continue."
20 WHILE T$<>"y" AND T$<>"Y" AND T$<>"n" AND T$<>"N"
30 T$=""
40 WHILE T$=""
50 T$ = INKEY$
60 WEND
70 IF T$<>"y" AND T$<>"Y" AND T$<>"n" AND T$<>"N" THEN BEEP
80 WEND
90 PRINT "The response was "; T$
</syntaxhighlight>
===={{header|GW-BASIC variant}}====
<syntaxhighlight lang="gwbasic">10 DEF FNUP$(C$)=CHR$(ASC(C$)-32*(ASC(C$)>96)*(ASC(C$)<123))
20 CLS: PRINT "Press Y or N to continue."
30 WHILE T$<>"Y" AND T$<>"N"
40 T$=FNUP$(INPUT$(1))
50 IF T$<>"Y" AND T$<>"N" THEN BEEP
60 WEND
70 PRINT "The response was: "; T$</syntaxhighlight>
==={{header|IS-BASIC}}===
<syntaxhighlight lang="is-basic">100 GET K$ ! Flush the keyboard buffer
110 PRINT "Press Y or N to continue."
120 DO
130 LET K$=LCASE$(INKEY$)
140 LOOP UNTIL K$="y" OR K$="n"
150 PRINT "The response was ";K$</syntaxhighlight>
==={{header|Locomotive Basic}}===
<syntaxhighlight lang="locobasic">10 CLEAR INPUT
20 PRINT "Press Y or N to continue"
30 a$=LOWER$(INKEY$)
40 IF a$="" THEN 30
50 IF a$="y" THEN PRINT "Yes":END
60 IF a$="n" THEN PRINT "No":END
70 PRINT "Try again"
80 GOTO 30</syntaxhighlight>
==={{header|True BASIC}}===
<syntaxhighlight lang="qbasic">LIBRARY "DefLib.trc"
DECLARE DEF INKEY$
PRINT "Press Y or N to continue."
DO
LET kbd$ = ""
DO WHILE kbd$ = ""
LET kbd$ = UCASE$(INKEY$)
LOOP
IF kbd$ <> "Y" AND kbd$ <> "N" THEN SOUND 800, .25
LOOP UNTIL kbd$ = "Y" OR kbd$ = "N"
PRINT "The response was "; kbd$
END</syntaxhighlight>
==={{header|Yabasic}}===
<syntaxhighlight lang="yabasic">clear screen
print "Do you want to continue y/n : ";
repeat
KBD$ = lower$(inkey$)
until KBD$ = "y" or KBD$ = "n"
print KBD$
if KBD$ = "y" then
print "OK, continuing"
else
print "OK, finishing"
end if</syntaxhighlight>
==={{header|ZX Spectrum Basic}}===
Note that this will also work in [[GW-BASIC]] and most [[QBasic]]-compatible BASICs if all instances of "<code>GO TO</code>" are changed to "<code>GOTO</code>".
50 PRINT "The response was "; k$</syntaxhighlight>
=={{header|Batch File}}==
<syntaxhighlight lang="dos">
@echo off
choice
if errorlevel 2 echo You chose N
if errorlevel 1 echo You chose Y
>nul pause
</syntaxhighlight>
=={{header|C}}==
For POSIX compliant systems (in theory that includes WinNT family).
<syntaxhighlight lang="c">
#include <stdio.h>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
void set_mode(int want_key)
{
static struct termios old, new;
if (!want_key) {
tcsetattr(STDIN_FILENO, TCSANOW, &old);
return;
}
tcgetattr(STDIN_FILENO, &old);
new = old;
new.c_lflag &= ~(ICANON);
tcsetattr(STDIN_FILENO, TCSANOW, &new);
}
int get_key(int no_timeout)
{
int c = 0;
struct timeval tv;
fd_set fs;
tv.tv_usec = tv.tv_sec = 0;
FD_ZERO(&fs);
FD_SET(STDIN_FILENO, &fs);
select(STDIN_FILENO + 1, &fs, 0, 0, no_timeout ? 0 : &tv);
if (FD_ISSET(STDIN_FILENO, &fs)) {
c = getchar();
set_mode(0);
}
return c;
}
int main()
{
int c;
while(1) {
set_mode(1);
while (get_key(0)); /* clear buffer */
printf("Prompt again [Y/N]? ");
fflush(stdout);
c = get_key(1);
if (c == 'Y' || c == 'y') {
printf("\n");
continue;
}
if (c == 'N' || c == 'n') {
printf("\nDone\n");
break;
}
printf("\nYes or no?\n");
}
return 0;
}</syntaxhighlight>
=={{header|C sharp}}==
<syntaxhighlight lang="c sharp">using System;
namespace Y_or_N
{
class Program
{
static void Main()
{
bool response = GetYorN();
}
static bool GetYorN()
{
ConsoleKey response; // Creates a variable to hold the user's response.
do
{
while (Console.KeyAvailable) // Flushes the input queue.
Console.ReadKey();
Console.Write("Y or N? "); // Asks the user to answer with 'Y' or 'N'.
response = Console.ReadKey().Key; // Gets the user's response.
Console.WriteLine(); // Breaks the line.
} while (response != ConsoleKey.Y && response != ConsoleKey.N); // If the user did not respond with a 'Y' or an 'N', repeat the loop.
/*
* Return true if the user responded with 'Y', otherwise false.
*
* We know the response was either 'Y' or 'N', so we can assume
* the response is 'N' if it is not 'Y'.
*/
return response == ConsoleKey.Y;
}
}
}</syntaxhighlight>
=={{header|C++}}==
Windows specific
<syntaxhighlight lang="cpp">#include <conio.h>
#include <iostream>
using namespace std;
int main()
{
char ch;
_cputs( "Yes or no?" );
do
{
ch = _getch();
ch = toupper( ch );
} while(ch!='Y'&&ch!='N');
if(ch=='N')
{
cout << "You said no" << endl;
}
else
{
cout << "You said yes" << endl;
}
return 0;
}
</syntaxhighlight>
=={{header|Clojure}}==
{{libheader|jline}}
Note: If you run it with Leiningen, use the special trampoline run to prevent issues:
<pre>$ lein trampoline run</pre>
<syntaxhighlight lang="clojure">
(ns yprompt.core
(:import jline.Terminal)
(:gen-class))
(defn yes? [k]
(if (or (= k 89) (= k 121)) true false))
(defn prompt []
(println "\nPrompt again [Y/N]?")
(let [term (Terminal/getTerminal)
ykey (yes? (.readCharacter term System/in))]
(if-not ykey
(recur)
(println "Yes!"))))
(defn -main [& args]
(prompt))
</syntaxhighlight>
=={{header|Common Lisp}}==
==={{header|LispWorks}}===
Version 1:
<syntaxhighlight lang="lisp">
(defun rosetta-y-or-n ()
(clear-input *query-io*)
(y-or-n-p))
</syntaxhighlight>
Version 2:
<syntaxhighlight lang="lisp">
(defun y-or-n ()
(clear-input *standard-input*)
(loop as dum = (format t "Y or N for yes or no: ")
as c = (read-char)
as q = (and (not (equal c #\n)) (not (equal c #\y)))
when q do (format t "~%Need Y or N~%")
unless q return (if (equal c #\y) 'yes 'no)))
</syntaxhighlight>
Version 1 and 2 work as required in a LispWorks GUI interface, i.e. they return immediately when the y or n keys are pressed, without waiting for the Enter key.
==={{header|ncurses}}===
When called from a REPL in a Linux terminal, y-or-n-p is ''line buffered'', which means any input has to be confirmed by an Enter key.
In order to have keys available immediately to the program, line buffering has to be disabled in the tty driver. This can be done by utilizing the ncurses terminal library available on most GNU/Linux systems. To interface ncurses from Lisp, the ''croatoan'' library can be used:
Version 3:
<syntaxhighlight lang="lisp">
(defun y-or-no ()
(with-screen (scr :input-buffering nil :input-blocking t)
(clear scr)
(princ "Do you want to continue? [Y/N]" scr)
(refresh scr)
(event-case (scr event)
((#\Y #\y) (return-from event-case t))
((#\N #\n) (return-from event-case nil)))))
</syntaxhighlight>
=={{header|D}}==
<syntaxhighlight lang="d">import std.stdio: stdout, write, writefln;
extern (C) nothrow {
void _STI_conio();
void _STD_conio();
int kbhit();
int getch();
}
void main() {
_STI_conio();
write("Enter Y or N: ");
stdout.flush();
int c;
do {
while(!kbhit()) {}
c = getch();
// Visual feedback for each keypress.
write(cast(char)c);
stdout.flush();
} while(c != 'Y' && c != 'y' && c != 'N' && c != 'n');
writefln("\nResponse: %c", cast(char)c);
_STD_conio();
}</syntaxhighlight>
{{out}}
<pre>Enter Y or N: abcN
Response: N</pre>
=={{header|Delphi}}==
{{libheader| System.Console}} Thanks for JensBorrisholt [https://github.com/JensBorrisholt/DelphiConsole].
<syntaxhighlight lang="delphi">
program Obtain_a_Y_or_N_response;
{$APPTYPE CONSOLE}
uses
System.Console;
function GetKey(acepted: string): Char;
var
key: Char;
begin
while True do
begin
if Console.KeyAvailable then
begin
key := UpCase(Console.ReadKey().KeyChar);
if pos(key, acepted) > 0 then
exit(key);
end;
end;
Result := #0; // Never Enter condition
end;
begin
Console.WriteLine('Press Y or N');
case GetKey('YN') of
'Y':
Console.WriteLine('You pressed Yes');
'N':
Console.WriteLine('You pressed No');
else
Console.WriteLine('We have a error');
end;
Readln;
end.</syntaxhighlight>
{{out}}
<pre>Press Y ou N
You pressed Yes</pre>
=={{header|EGL}}==
{{Works with|EDT}}
{{Works with|RBD}}
<syntaxhighlight lang="egl">handler YesOrNoHandler type RUIhandler{initialUI =[ui], onConstructionFunction = start}
ui Div { };
const KEY_N int = 78;
const KEY_Y int = 89;
function start()
document.onKeyDown = d_onKeyDown;
end
function d_onKeyDown(e Event in)
case (e.ch)
when (KEY_N)
ui.innerText = "N pressed.";
when (KEY_Y)
ui.innerText = "Y pressed.";
end
e.preventDefault();
end
end</syntaxhighlight>
=={{header|Elm}}==
<syntaxhighlight lang="elm">import Char
import Graphics.Element exposing (Element, empty, show)
import Keyboard
view : Int -> Element
view keyCode =
let
char =
Char.fromCode keyCode
showChar =
toString >> ((++) "The last (y/n) key pressed was: ") >> show
in
case char of
'n' ->
showChar char
'y' ->
showChar char
_ ->
empty
main : Signal Element
main =
Signal.map view Keyboard.presses</syntaxhighlight>
=={{header|ERRE}}==
<syntaxhighlight lang="erre">
!$KEY
................
! flush the keyboard buffer
! --------------------------------
! you can use POKE(198,0) in C-64
! ERRE version
! --------------------------------
REPEAT
GET(K$)
UNTIL K$=""
PRINT("Press Y or N to continue")
REPEAT
GET(K$)
UNTIL INSTR("YyNn",K$)<>0
!
! with C-64 you must write a line like
! UNTIL K$="Y" OR K$="N"
!
PRINT("The response was ";K$)
.................
</syntaxhighlight>
<code>!$KEY </code> is a directive pragma: using it <code>GET</code> become an equivalent to Qbasic INKEY$, otherwise it's equivalent to QBasic INPUT$(1). !$KEY is also used to mantain portability with the C-64 version of ERRE language.
=={{header|Euphoria}}==
<syntaxhighlight lang="euphoria">integer key
puts(1,"Your answer? (Y/N)\n")
while get_key()!=-1 do
end while
while 1 do
key = get_key()
if key!=-1 and (key = 'Y' or key = 'y' or key = 'N' or key = 'n') then
exit
end if
end while
printf(1,"Your response was %s\n",key)</syntaxhighlight>
=={{header|F_Sharp|F#}}==
<syntaxhighlight lang="fsharp">open System
let rec yorn () =
let rec flush () = if Console.KeyAvailable then ignore (Console.ReadKey()); flush ()
flush ()
printf "\nY or N? "
match Console.ReadKey().Key with
| ConsoleKey.Y -> 'Y'
| ConsoleKey.N -> 'N'
| _ -> yorn()
printfn "\nYour choice: %c" (yorn())</syntaxhighlight>
=={{header|Forth}}==
<syntaxhighlight lang="forth">: flush ( -- ) \ discard pending input
begin key? while key drop repeat ;
: y-or-n ( c-addr u -- f )
flush begin
cr 2dup type key bl or \ note 1.
dup [char] y = swap [char] n = over or \ note 2.
if nip nip exit then
drop again ;
\ Note 1. KEY BL OR returns a lowercase letter in the case that an
\ uppercase letter was entered, an unchanged lowercase letter in the
\ case that a lowercase letter was entered, and garbage otherwise. BL
\ returns the ASCII code for a space, 32, which is incidentally the
\ "bit of difference" between ASCII uppercase and lowercase letters.
\ Note 2. this line has the stack effect ( x -- f1 f2 ), where F1 is
\ true only if x='y', and F2 is true only if x='y' OR if x='n'.
\ I think these expressions aren't too clever, but they _are_ rather
\ optimized for the task at hand. This might be more conventional:
: y-or-n ( c-addr u -- f )
flush begin
cr 2dup type key case
[char] y of 2drop true exit endof
[char] Y of 2drop true exit endof
[char] n of 2drop false exit endof
[char] N of 2drop false exit endof
endcase again ;</syntaxhighlight>
=={{header|Fortran}}==
Standard Fortran has no special I/O statements that allow asynchronous actions (such as the KeyPressed and ReadKey functions of Turbo Pascal), so input is awaited in the usual fashion and a prompt should be supplied to indicate to the reader that a response is awaited, otherwise the user will confront a blank screen with nothing happening and will have to guess what might be expected. Further, there is no scheme for knowing if impending input has been waiting in an input buffer since before the need for a question arose, so it is not possible to flush such lines before requesting the special input. Impatience at the screenface can prompt typing ahead so that the next command will be immediately available but incorrectly anticipated input will likely wreck the run, though for yes/no responses you may be rescued if such input does not conform to the required form: the bad input will be ignored and the question asked afresh. Thus, the details of the specification cannot be met via standard Fortran, though a given system may have special subroutines equivalent to KeyPressed, etc. available.
Even so, asking questions can often be useful when messing about with tests, etc., so some routines for this can help. These were devised afresh at the Culham Science Centre, so there was some language generality:
<syntaxhighlight lang="fortran">
CHARACTER*120 FUNCTION REPLY(QUERY) !Obtain a text in reply.
Concocted by R.N.McLean (whom God preserve), December MM.
CHARACTER*(*) QUERY !The question.
CHARACTER*120 TEXT !Alas, oh for proper strings.
INTEGER MSG,KEYS,LSTNB !Let's hope everyone has the same type.
COMMON /IOUNITS/ MSG,KEYS!Orifices.
WRITE (MSG,1) QUERY(1:LSTNB(QUERY)),"?"!So, splurt.
1 FORMAT (2A,$) !A trailing text literal may not be rolled.
READ (KEYS,1) TEXT !Dare not use REPLY itself. Some implementations bungle.
REPLY = TEXT !So, shuffle.
RETURN !Take that.
END !Others interpret the reply.
REAL*8 FUNCTION REPLYN(QUERY) !Obtain a number in reply.
Concocted by R.N.McLean (whom God preserve), December MM.
CHARACTER*(*) QUERY !The question.
REAL X !The answer, presumably not 42.
INTEGER MSG,KEYS,LSTNB !Let's hope everyone has the same type.
COMMON /IOUNITS/ MSG,KEYS!Orifices.
1 WRITE (MSG,2) QUERY(1:LSTNB(QUERY)) !No trailing spaces.
2 FORMAT (A,$) !The $ obviously suppresses the newline.
READ (KEYS,*,ERR = 3) X !Presume adequate testing for now.
REPLYN = X !The value!
RETURN !All done.
3 WRITE (MSG,4) !Or perhaps not.
4 FORMAT ('Distasteful number. Try again...') !All sorts of ways.
GO TO 1 !My patience is unconditional.
END !One way or another, a number will be secured.
LOGICAL FUNCTION YEA(QUERY) !Obtain a Yes in reply?
Concocted by R.N.McLean (whom God preserve), December MM.
CHARACTER*(*) QUERY !The question.
CHARACTER*120 WHAT,REPLY !Quite so.
CHARACTER*1 C !Scratchpad.
INTEGER MSG,KEYS !Let's hope everyone has the same type.
COMMON /IOUNITS/ MSG,KEYS!Orifices.
INTEGER L !A finger.
1 WHAT = REPLY(QUERY) !So, get an answer.
DO L = 1,LEN(WHAT) !Sigh. Oh for Trim(string)
C = WHAT(L:L) !Sniff a CHARACTER.
IF (C .NE. ' ') GO TO 10 !A starter?
END DO !No. Try further on.
WRITE (MSG,2) !Surely not.
2 FORMAT ('All blank?') !Poke.
3 WRITE (MSG,4) !Sigh.
4 FORMAT ('I dig it not. Try Yes/Si/Da/Oui/Ja, or No')
GO TO 1 !Get it right, this time?
10 IF (INDEX('YySsDdOoJj',C) .GT. 0) THEN !Yes/Si/Da/Oui/Ja...
YEA = .TRUE. !A decision.
ELSE IF (INDEX('Nn',C) .GT. 0) THEN !No,No,Nyet,Non...
YEA = .FALSE. !Even if negative.
ELSE !But if unrecognised,
GO TO 3 !Try again.
END IF !So much for choices.
RETURN !Pass the word.
END !Enough of yes-beings.
LOGICAL FUNCTION NAY(QUERY) !Perhaps this reads better.
Concocted by R.N.McLean (whom God preserve), December MM.
CHARACTER*(*) QUERY !The question.
LOGICAL YEA !Let us hope so.
NAY = .NOT.YEA(QUERY) !Straightforward.
RETURN !Pass the inverted word.
END !So much for naysayers.
</syntaxhighlight>
Usage might be something like <code>IF (NAY("Keep the results")) CALL PURGE</code>
=={{header|FreeBASIC}}==
<syntaxhighlight lang="freebasic">' FB 1.05.0 Win64
While InKey <> "" : Wend '' flush keyboard buffer
Print "Do you want to continue y/n : ";
Dim answer As String
Do
answer = LCase(Inkey)
Loop Until answer = "y" OrElse answer = "n"
Print answer '' echo response to console
If answer = "y" Then
Print "OK, continuing"
Else
Print "OK, finishing"
End If
Sleep</syntaxhighlight>
Sample input/output:
{{out}}
<pre>
Do you want to continue y/n : y
OK, continuing
</pre>
=={{header|FutureBasic}}==
<syntaxhighlight lang="futurebasic">void local fn DoDialog( ev as long )
CFStringRef key
select ( ev )
case _windowKeyDown
cls
key = fn EventCharacters
select ( lcase(key) )
case @"y",@"n"
printf @"You pressed the \"%@\" key",key
DialogEventSetBool(YES)// we handled the event
end select
end select
end fn
subclass
window 1, @"Press \"Y\" or \"N\" keys", (0,0,550,400)
on dialog fn DoDialog
HandleEvents</syntaxhighlight>
=={{header|GlovePIE}}==
<syntaxhighlight lang="glovepie">if var.end=0 then
var.end=0
debug="Press the Y key or the N key to continue:"
endif
if pressed(Key.Y)and var.end=0 then
var.end=1
debug="You pressed the Y key."
endif
if pressed(Key.N)and var.end=0 then
var.end=1
debug="You pressed the N key."
endif</syntaxhighlight>
=={{header|Go}}==
{{libheader|Curses}}
<syntaxhighlight lang="go">package main
import (
"log"
gc "code.google.com/p/goncurses"
)
func main() {
s, err := gc.Init()
if err != nil {
log.Fatal("init:", err)
}
defer gc.End()
var k gc.Key
for {
gc.FlushInput()
s.MovePrint(20, 0, "Press y/n ")
s.Refresh()
switch k = s.GetChar(); k {
default:
continue
case 'y', 'Y', 'n', 'N':
}
break
}
s.Printf("\nThanks for the %c!\n", k)
s.Refresh()
s.GetChar()
}</syntaxhighlight>
::<syntaxhighlight lang="go">package main
// siongui.github.io/2016/04/23/go-read-yes-no-from-console
import (
"fmt"
"strings"
)
func ask() bool {
var s string
fmt.Printf("(y/n): ")
fmt.Scan(&s)
s = strings.TrimSpace(s)
s = strings.ToLower(s)
if s == "y" || s == "yes" {
return true
}
return false
}
func main() {
ans := ask()
if ans {
fmt.Println("yes")
} else {
fmt.Println("no")
}
}</syntaxhighlight>
=={{header|GW-BASIC}}==
<syntaxhighlight lang="qbasic">10 IF INKEY$<>"" THEN GOTO 10: REM flush the keyboard buffer
20 PRINT "Press Y or N to continue"
30 LET k$ = INKEY$
40 IF k$ <> "y" AND k$ <> "Y" AND k$ <> "n" AND k$ <> "N" THEN GOTO 30
50 PRINT "The response was "; k$</syntaxhighlight>
=={{header|Haskell}}==
This may not be very idiomatic; it's pretty monad-oriented, and the use of do expressions makes the whole thing feel rather imperative.
<syntaxhighlight lang="haskell">import System.IO
hFlushInput :: Handle -> IO ()
hFlushInput hdl = do
r <- hReady hdl
if r then do
c <- hGetChar hdl
hFlushInput hdl
else
return ()
yorn :: IO Char
yorn = do
c <- getChar
if c == 'Y' || c == 'N' then return c
else if c == 'y' then return 'Y'
else if c == 'n' then return 'N'
else yorn
main :: IO ()
main = do
hSetBuffering stdout NoBuffering
putStr "Press Y or N to continue: "
hSetBuffering stdin NoBuffering
hSetEcho stdin False
hFlushInput stdin
answer <- yorn
putStrLn [answer]</syntaxhighlight>
=={{header|Icon}} and {{header|Unicon}}==
This solution works in both Icon and Unicon. It also accepts <tt>y</tt> or <tt>n</tt>.
<syntaxhighlight lang="unicon">procedure main()
write("Response was ",getResponse("OK? (Y or N): "))
end
procedure getResponse(prompt)
while kbhit() do getch() # flush input
writes(prompt)
repeat if map(answer := getch()) == ("y"|"n") then break
return answer
end</syntaxhighlight>
=={{header|Inform 7}}==
Keyboard input goes through a virtual machine that's only required to provide blocking input operations, so flushing the buffer isn't possible.
Inform 7 has a built-in function to ask the user for yes-or-no input, but it requires them to press enter afterward:
<syntaxhighlight lang="inform7">Qwantz is a room.
When play begins:
say "A wizard has turned you into a whale. Is this awesome (Y/N)? ";
if the player consents, say "Awesome!";
end the story.</syntaxhighlight>
To read a single key without waiting for enter, we can redefine the function by including a snippet of Inform 6 code:
<syntaxhighlight lang="inform7">To decide whether player consents: (- (YesOrNoKey()) -).
Include (-
[ YesOrNoKey ch;
do { ch = VM_KeyChar(); } until (ch == 'y' or 'Y' or 'n' or 'N');
return ch == 'y' or 'Y';
]; -).</syntaxhighlight>
=={{header|Java}}==
The task specification that there should be no need for the user to press the enter key,
creates an awkward situation for the Java language.
However, a short program that waits for the user to press return can easily be constructed.
<syntaxhighlight lang="java">
import java.awt.event.KeyEvent;
import java.io.IOException;
import java.awt.EventQueue;
import java.awt.event.KeyAdapter;
import javax.swing.JFrame;
public final class KeyboardInputObtainYOrN {
public static void main(String[] aArgs) {
EventQueue.invokeLater( () -> { new Test("Obtain Y or N"); } );
}
}
final class Test extends JFrame {
public Test(String aTitle) {
super(aTitle);
addKeyListener( new YesOrNoKeyAdapter() );
setVisible(true);
try {
while ( System.in.available() > 0 ) {
System.in.read();
}
} catch (IOException ioe) {
ioe.printStackTrace();
}
System.out.println("Do you want to quit the program? Y / N");
}
}
final class YesOrNoKeyAdapter extends KeyAdapter {
@Override
public void keyPressed(KeyEvent aKeyEvent) {
if ( aKeyEvent.getKeyCode() == KeyEvent.VK_Y ) {
System.out.println("Y was pressed, quitting the program");
Runtime.getRuntime().exit(0);
} else if ( aKeyEvent.getKeyCode() == KeyEvent.VK_N ) {
System.out.println("N was pressed, but the program is about to end anyway");
Runtime.getRuntime().exit(0);
} else {
System.out.println("Please try again, only Y or N are acceptable");
}
}
}
</syntaxhighlight>
=={{header|JavaScript}}==
Here's a synchronous ES6 implementation. The synchronous code must be executed in an async function definition. In this example, `wait_key` returns the key pressed and `done` must be called decouple the listening to stdin and end the process. The example pauses for a second to show that the keys pressed before `wait_key` is called are not heard.
<syntaxhighlight lang="javascript">const readline = require('readline');
readline.emitKeypressEvents(process.stdin);
process.stdin.setRawMode(true);
var wait_key = async function() {
return await new Promise(function(resolve,reject) {
var key_listen = function(str,key) {
process.stdin.removeListener('keypress', key_listen);
resolve(str);
}
process.stdin.on('keypress', key_listen);
});
}
var done = function() {
process.exit();
}
var go = async function() {
do {
console.log('Press any key...');
var key = await wait_key();
console.log("Key pressed is",key);
await new Promise(function(resolve) { setTimeout(resolve,1000); });
} while(key != 'y');
done();
}
go();
</syntaxhighlight>
Here's how you can asynchronously read a single character in Node.js, using the <code>keypress</code> package.
This does not seem to be possible to do synchronously in Node.js or at all in the SpiderMonkey shell.
<syntaxhighlight lang="javascript">var keypress = require('keypress');
keypress(process.stdin);
process.stdin.on('keypress', function (ch, key) {
if (key && (key.name === 'y' || key.name === 'n')) {
console.log('Reply:' + key.name);
}
});
process.stdin.setRawMode(true);
process.stdin.resume();</syntaxhighlight>
Using DOM events.
<syntaxhighlight lang="javascript">document.body.addEventListener('keyup', function (e) {
var key = String.fromCharCode(e.keyCode).toLowerCase();
if (key === 'y' || key === 'n') {
console.log('response is: ' + key);
}
}, false);</syntaxhighlight>
=={{header|Julia}}==
Uses the Gtk library.
<syntaxhighlight lang="julia">using Gtk.ShortNames
function keypresswindow()
# This code creates the Gtk widgets on the screen.
txt = "Type Y or N"
win = Window("Keypress Test", 250, 30) |> (Frame() |> ((vbox = Box(:v)) |> (lab = Label(txt))))
# this is the keystroke processing code, a function and a callback for the function.
function keycall(w, event)
ch = Char(event.keyval)
set_gtk_property!(lab,:label, ch in('n','N','y','Y') ? "You hit the $ch key." : txt)
end
Gtk.signal_connect(keycall, win, "key-press-event")
# this code sets up a proper exit when the widow is closed.
c = Condition()
endit(w) = notify(c)
Gtk.signal_connect(endit, win, :destroy)
Gtk.showall(win)
wait(c)
end
keypresswindow()
</syntaxhighlight>
=={{header|Kotlin}}==
<syntaxhighlight lang="scala">// version 1.0.6
import java.awt.event.KeyAdapter
import java.awt.event.KeyEvent
import javax.swing.JFrame
import javax.swing.SwingUtilities
class Test: JFrame() {
init {
while (System.`in`.available() > 0) System.`in`.read()
println("Do you want to quit Y/N")
addKeyListener(object: KeyAdapter() {
override fun keyPressed(e: KeyEvent) {
if (e.keyCode == KeyEvent.VK_Y) {
println("OK, quitting")
quit()
} else if (e.keyCode == KeyEvent.VK_N) {
println("N was pressed but the program is about to end anyway")
quit()
} else {
println("Only Y/N are acceptable, please try again")
}
}
})
}
private fun quit() {
isVisible = false
dispose()
System.exit(0)
}
}
fun main(args: Array<String>) {
SwingUtilities.invokeLater {
val f = Test()
f.isFocusable = true
f.isVisible = true
}
}</syntaxhighlight>
=={{header|Liberty BASIC}}==
<syntaxhighlight lang="lb">
nomainwin
open "Y/N" for graphics_nsb_nf as #1
#1 "trapclose Quit"
#1 "down;setfocus;when characterInput KeyCheck"
#1 "place 10 50;\Press Y or N"
Inkey$=""
wait
sub KeyCheck hndle$,k$
k$=upper$(k$)
#hndle$ "cls;place 10 50"
select case k$
case "Y"
#hndle$ "\ Yes"
case "N"
#hndle$ "\No"
case else
#hndle$ "\Incorrect input. Press Y or N"
end select
end sub
sub Quit hndle$
close #hndle$
end
end sub
</syntaxhighlight>
=={{header|LiveCode}}==
In the Card script, add a handler for the OpenCard event, putting empty into the text field.
In the text field, put the following in its code
<syntaxhighlight lang="livecode">on KeyDown k
if toUpper(k) is among the items of "Y,N" then
answer "Thanks for your response"
else
answer "You need to enter Y or N"
end if
put empty into me
end KeyDown</syntaxhighlight>
n.b. This sort of confirmation in GUI apps is usually presented as a dialog box with Yes/No buttons, which automatically handles keyboard input.
=={{header|Logo}}==
<syntaxhighlight lang="logo">to yorn
type [Press Y or N to continue: ]
local "clear
make "clear readchars 0 ; clear input buffer
local "yorn
do.until [make "yorn readchar] [or equal? :yorn "Y equal? :yorn "N]
print :yorn
output :yorn
end</syntaxhighlight>
=={{header|M2000 Interpreter}}==
===Simple Loop using Key$===
If keyboard is Greek the we have to change to English. Other examples use Keyboard codes.
<syntaxhighlight lang="m2000 interpreter">
Module Simple {
\\ a small modification from BBC BASIC entry
REPEAT {} UNTIL INKEY$ = ""
PRINT "Press Y or N to continue"
REPEAT {
k$ =Ucase$(Key$)
} UNTIL K$="Y" OR k$="N"
PRINT "The response was "; k$
}
Simple
</syntaxhighlight>
===Use a Function to return keypress and by reference return value===
<syntaxhighlight lang="m2000 interpreter">
Module Checkit {
Function GetYN$ (&Ret) {
const Y=0x59
const N=0x4E
Ret=False
Do {
if keypress(Y) then Ret=True : exit
if keypress(N) then exit
drop$=inkey$
} Always
K$=key$
do {} until filter$(Inkey$,k$)=""
=Ucase$(K$)
}
keyboard "abcde" ' feed keyboard (inkey$ get these characters)
Y=0
Print "Your answer (Y/N):"; GetYN$(&Y)
Print Y
}
Checkit
</syntaxhighlight>
===Using Thread to read/write Keyboard buffer===
We use a thread, using after, for one run, after 10ms, when Input wait for keypress. So when call to GetYN module exit has Y or N with Enter to keyboard. Now Input finish.
Threads runs in same namespace as the module they created. So module name and Y variable are visible.Module GetYN can't read parent module variables, except M which declared as GLOBAL. After 500ms N is returned.
Using Profiler and Print Timecount we get the real duration (using high resolution timer), of response.
<syntaxhighlight lang="m2000 interpreter">
Module CheckisToo {
Module GetYN (&Ret) {
const Y=0x59
const N=0x4E
Ret=False
Do {
If M>50 then Keyboard "N" : exit
if keypress(Y) then Ret=True : exit
if keypress(N) then exit
drop$=inkey$
\\ ensure thread MM run using wait
wait 1
} Always
Keyboard Ucase$(Key$)+Chr$(13)
}
keyboard "abcde"
Y=0
Global M=0
Thread {
M++
} as MM interval 10
While Inkey$<>"" {}
After 10 {
Module GetYN &Y
}
Profiler
Input "Your answer (Y/N):", A$
Print timecount
Print Y, M
Threads Erase
}
CheckisToo
</syntaxhighlight>
===Using User Form (GUI)===
<syntaxhighlight lang="m2000 interpreter">
Module UseUIForm {
Const Y=0x59, N=0x4E, Center=2
Ret=False
Declare Form1 form
Layer Form1 {
Window 22, 8000, 4000;
Cls #333333,0
Cursor 0, Height/2
Report Center, "Press (Y/N)"
}
Function form1.Keydown {
Read New &key, &shiftKey
IF key=Y then ret=True : Method Form1, "CloseNow"
If key=N Then Method Form1, "CloseNow"
}
Method Form1, "Show", 1 ' modal show
Print Ret
Declare Form1 Nothing
}
UseUIForm
</syntaxhighlight>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
<syntaxhighlight lang="mathematica">CreateDialog[TextCell["Yes or no?[Y/N]"],
NotebookEventActions -> {
"KeyDown" :> Switch[ToUpperCase@CurrentValue["EventKey"],
"Y", Print["You said yes"]; DialogReturn[],
"N", Print["You said no"]; DialogReturn[]
]}];</syntaxhighlight>
=={{header|Microsoft Small Basic}}==
Submitted by: '''AykayayCiti''' (''Earl L. Montgomery'') on Mar 19, 2018.
Once you hit a key a separate dialog box will appear. Place them side by side to see the results.
<syntaxhighlight lang="vb">'From:
'Andy Oneill, 2-6-2015, "Small Basic: Key Input,
'" TechNet, https://social.technet.microsoft.com/wiki/contents/articles/29850.small-basic-key-input.aspx, accessed 3-19-2018
GraphicsWindow.DrawText(10, 10, "Hit any key to dump.")
GraphicsWindow.KeyDown = OnKeyDown
Sub OnKeyDown
TextWindow.WriteLine(GraphicsWindow.LastKey)
EndSub</syntaxhighlight>
=={{header|MiniScript}}==
{{works with|Mini Micro}}
Access to hardware like the keyboard is very dependent on the host app, but here's a version that works with [https://miniscript.org/MiniMicro/ MiniMicro], a standardized MiniScript virtual machine.
<syntaxhighlight lang="miniscript">// flush the keyboard
while key.available
key.get
end while
// and now prompt and wait for Y or N
print "Press Y or N:"
k = ""
while k != "Y" and k != "N"
k = key.get.upper
end while
print "You pressed: " + k</syntaxhighlight>
=={{header|MUMPS}}==
{{works with|Caché ObjectScript}}
Version from terminal shown below.
<syntaxhighlight lang="mumps">for read !,"Enter Y or N to continue: ",input quit:input?1(1"Y",1"y",1"N",1"n")</syntaxhighlight>
{{out}}<pre>Enter Y or N to continue: J
Enter Y or N to continue: YES
Enter Y or N to continue: no
Enter Y or N to continue: N
SAMPLES> </pre>
=={{header|NetRexx}}==
<syntaxhighlight lang="netrexx">/* NetRexx */
options replace format comments java crossref savelog symbols binary
Say 'Please enter Y or N'
parse ask c
Select
when c='Y' Then Say 'YES'
when c='N' Then Say 'NO'
otherwise Say 'Undecided'
End </syntaxhighlight>
=={{header|Nim}}==
{{libheader|gintro}}
Using "gintro" bindings to Gtk3.
<syntaxhighlight lang="nim">import strformat
import gintro/[glib, gobject, gtk, gio]
import gintro/gdk except Window
#---------------------------------------------------------------------------------------------------
proc onKeyPress(window: ApplicationWindow; event: Event; label: Label): bool =
var keyval: int
if not event.getKeyval(keyval): return false
if keyval in [ord('n'), ord('y')]:
label.setText(&"You pressed key '{chr(keyval)}'")
result = true
#---------------------------------------------------------------------------------------------------
proc activate(app: Application) =
## Activate the application.
let window = app.newApplicationWindow()
window.setTitle("Y/N response")
let hbox = newBox(Orientation.horizontal, 0)
window.add(hbox)
let vbox = newBox(Orientation.vertical, 10)
hbox.packStart(vbox, true, true, 20)
let label1 = newLabel(" Press 'y' or 'n' key ")
vbox.packStart(label1, true, true, 5)
let label2 = newLabel()
vbox.packStart(label2, true, true, 5)
discard window.connect("key-press-event", onKeyPress, label2)
window.showAll()
#———————————————————————————————————————————————————————————————————————————————————————————————————
let app = newApplication(Application, "Rosetta.YNResponse")
discard app.connect("activate", activate)
discard app.run()</syntaxhighlight>
=={{header|NS-HUBASIC}}==
<syntaxhighlight lang="ns-hubasic">10 PRINT "PRESS Y OR N TO CONTINUE."
20 IF INKEY$<>"Y" AND INKEY$<>"N" THEN GOTO 20
30 PRINT "THE RESPONSE WAS ";INKEY$;"."</syntaxhighlight>
=={{header|OCaml}}==
<code>Unix</code> module, exposing POSIX interfaces like [https://en.wikipedia.org/wiki/POSIX_terminal_interface termios], is normally bundled with any standard OCaml distribution. Utilizing termios is the solution many other language examples here went with.
OCaml needs to link to the bundled unix archives correctly in order to compile / run code that uses definitions within the module. To do this with the plain OCaml toolchain, remember to add the library archive to the commandline like so:
<code>ocaml unix.cma <yourfile.ml></code> interpreted<br/>
<code>ocamlc -o <progname> unix.cma <yourfile.ml></code> bytecode executable<br/>
<code>ocamlopt -o <progname> unix.cmxa <yourfile.ml></code> native executable
Here we define some helper functions that we'll use:
<syntaxhighlight lang="ocaml">let attrs = Unix.(tcgetattr stdin)
let buf = Bytes.create 1
let prompt switch =
Unix.(tcsetattr stdin TCSAFLUSH)
@@ if switch then { attrs with c_icanon = false } else attrs
let getchar () =
let len = Unix.(read stdin) buf 0 1 in
if len = 0 then raise End_of_file else Bytes.get buf 0</syntaxhighlight>
Now the main program:
<syntaxhighlight lang="ocaml">let rec loop () =
print_string "Prompt? [Y/N]: "; flush stdout;
loop
@@ print_endline
@@ match getchar () with
| 'n' | 'N' -> raise Exit
| 'y' | 'Y' -> ": Ok."
| _ -> ": Invalid."
let _ = try loop @@ prompt true with Exit | End_of_file -> prompt false</syntaxhighlight>
=={{header|Oforth}}==
<syntaxhighlight lang="oforth">import: console
: YorN
| c |
System.Console flush
doWhile: [
System.Console receiveChar toUpper ->c
c 'Y' <> c 'N' <> and
]
c ;</syntaxhighlight>
=={{header|OpenEdge/Progress}}==
<syntaxhighlight lang="progress">DEF VAR lanswer AS LOGICAL INITIAL ?.
DO WHILE lanswer = ?:
READKEY.
IF CHR( LASTKEY ) = "n" OR CHR( LASTKEY ) = "y" THEN
lanswer = CHR( LASTKEY ) = "y".
END.
MESSAGE lanswer VIEW-AS ALERT-BOX.</syntaxhighlight>
=={{header|PARI/GP}}==
GP's <code>input</code> is not able to read an unbuffered single character, so one must use PARI where the solution is identical to that of [[#C|C]].
=={{header|Pascal}}==
{{works with|Free_Pascal}}
{{libheader|CRT}}
<syntaxhighlight lang="pascal">Program ObtainYN;
uses
crt;
var
key: char;
begin
write('Your answer? (Y/N): ');
repeat
key := readkey;
until (key in ['Y', 'y', 'N', 'n']);
writeln;
writeln ('Your answer was: ', key);
end.</syntaxhighlight>
Output:
<pre>% ./ObtainYN
Your answer? (Y/N):
Your answer was: y
</pre>
=={{header|Perl}}==
<syntaxhighlight lang="perl">use Term::ReadKey;
ReadMode 4; # change to raw input mode
my $key = '';
while($key !~ /(Y|N)/i) {
1 while defined ReadKey -1; # discard any previous input
print "Type Y/N: ";
$key = ReadKey 0; # read a single character
print "$key\n";
}
ReadMode 0; # reset the terminal to normal mode
print "\nYou typed: $key\n";
</syntaxhighlight>
=={{header|Phix}}==
{{libheader|Phix/basics}}
For 1970s-style character console (/beginner) applications:
<!--<syntaxhighlight lang="phix">-->
<span style="color: #004080;">integer</span> <span style="color: #000000;">key</span>
<span style="color: #008080;">while</span> <span style="color: #7060A8;">get_key</span><span style="color: #0000FF;">()!=-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span> <span style="color: #008080;">end</span> <span style="color: #008080;">while</span> <span style="color: #000080;font-style:italic;">-- flush</span>
<span style="color: #7060A8;">puts</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"Your answer? (Y/N)"</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">while</span> <span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #000000;">key</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">upper</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">get_key</span><span style="color: #0000FF;">())</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">find</span><span style="color: #0000FF;">(</span><span style="color: #000000;">key</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"YN"</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">then</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"\nYour response was %s\n"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">key</span><span style="color: #0000FF;">)</span>
<!--</syntaxhighlight>-->
For GUI (graphical user interface) applications, use something more like this:
<!--<syntaxhighlight lang="phix">-->
<span style="color: #008080;">function</span> <span style="color: #000000;">key_cb</span><span style="color: #0000FF;">(</span><span style="color: #004080;">Ihandle</span> <span style="color: #000080;font-style:italic;">/*ih*/</span><span style="color: #0000FF;">,</span> <span style="color: #004080;">atom</span> <span style="color: #000000;">c</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">lower</span><span style="color: #0000FF;">(</span><span style="color: #000000;">c</span><span style="color: #0000FF;">)=</span><span style="color: #008000;">'y'</span> <span style="color: #008080;">then</span> <span style="color: #000000;">y_keyed</span><span style="color: #0000FF;">()</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">if</span> <span style="color: #7060A8;">lower</span><span style="color: #0000FF;">(</span><span style="color: #000000;">c</span><span style="color: #0000FF;">)=</span><span style="color: #008000;">'n'</span> <span style="color: #008080;">then</span> <span style="color: #000000;">n_keyed</span><span style="color: #0000FF;">()</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">return</span> <span style="color: #004600;">IUP_CONTINUE</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #7060A8;">IupSetCallback</span><span style="color: #0000FF;">(</span><span style="color: #000000;">dlg</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"K_ANY"</span><span style="color: #0000FF;">,</span> <span style="color: #7060A8;">Icallback</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"key_cb"</span><span style="color: #0000FF;">))</span>
<!--</syntaxhighlight>-->
See [[Keyboard_macros#Phix]] or [[Conway%27s_Game_of_Life#Phix]] for a more complete example
=={{header|PicoLisp}}==
<syntaxhighlight lang="picolisp">(de yesno ()
(loop
(NIL (uppc (key)))
(T (= "Y" @) T)
(T (= "N" @)) ) )</syntaxhighlight>
=={{header|PL/I}}==
<syntaxhighlight lang="pli"> yn: Proc Options(main):
Dcl sysin stream input;
Dcl sysprint stream output;
Dcl c Char(1);
Put Skip List('Please enter Y or N');
Get Edit(c)(a(1));
Select(c);
When('Y','y','J','j')
Put Skip List('YES');
When('N','n')
Put Skip List('NO');
Otherwise
Put Skip List('Undecided?');
End;
End;</syntaxhighlight>
=={{header|PowerShell}}==
This is for console use only. The ISE is geared for a different type of input.
<syntaxhighlight lang="powershell">
do
{
$keyPress = [System.Console]::ReadKey()
}
until ($keyPress.Key -eq "Y" -or $keyPress.Key -eq "N")
$keyPress | Format-Table -AutoSize
</syntaxhighlight>
If the user pressed the "Y" key...
{{Out}}
<pre>
KeyChar Key Modifiers
------- --- ---------
y Y 0
</pre>
If the user pressed the "N" key...
{{Out}}
<pre>
KeyChar Key Modifiers
------- --- ---------
n N 0
</pre>
=={{header|PureBasic}}==
Inkey() returns the character string of the key which is being pressed at the time.
<
Repeat
Line 29 ⟶ 1,767:
Delay(1)
Until Key$="Y" Or Key$="N"
PrintN("The response was "+Key$)</
=={{header|Python}}==
<syntaxhighlight lang="python">#!/usr/bin/env python
try:
from msvcrt import getch
except ImportError:
def getch():
import sys, tty, termios
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(sys.stdin.fileno())
ch = sys.stdin.read(1)
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
print "Press Y or N to continue"
while True:
char = getch()
if char.lower() in ("y", "n"):
print char
break</syntaxhighlight>
----
<syntaxhighlight lang="python">#!/usr/bin/env python
# -*- coding: utf-8 -*-
from curses import wrapper
#
#
def main(stdscr):
# const
#y = ord("y")
#n = ord("n")
while True:
# keyboard input interceptor|listener
#window.nodelay(yes)
# - If yes is 1, getch() will be non-blocking.
# return char code
#kb_Inpt = stdscr.getch()
# return string
kb_Inpt = stdscr.getkey()
#if kb_Inpt == (y or n):
if kb_Inpt.lower() == ('y' or 'n'):
break
return None
#
return None
#
#*** unit test ***#
if __name__ == "__main__":
#
wrapper(main)</syntaxhighlight>
=={{header|QB64}}==
''CBTJD'': 2020/03/15
<syntaxhighlight lang="qbasic">WHILE INKEY$ <> "": WEND ' Flushes keyboard buffer.
PRINT "Do you want to continue? (Y/N)"
DO
k$ = UCASE$(INKEY$) ' Forces key response to upper case.
LOOP UNTIL k$ = "Y" OR k$ = "N"
PRINT "You pressed " + CHR$(34) + k$ + CHR$(34) + "." ' CHR$(34) prints quotation marks.</syntaxhighlight>
=={{header|QUACKASM}}==
Note: The following is not a full program (it is only a subroutine, using standard calling conventions), nor does it flush the keyboard buffer (there is no standard way to do this in QUACKVM; it may be possible using extensions, but none are currently defined).
<syntaxhighlight lang="quackasm">
; Stores result in cell 2; 1 if yes, 0 if no.
:YORN
PRINT YORNMSG
:YORN1
INPUT >2
AND *2,$5F,'Y >2 /YORN2
AND *2,,'N \YORN1
:YORN2
PRINTC *2
PRINTC 13
AND *2,1 >2
RETURN
:YORNMSG " (Y/N)? \
</syntaxhighlight>
=={{header|Racket}}==
<syntaxhighlight lang="racket">
#lang racket
;; GUI version
(require racket/gui)
(message-box "Yes/No example" "Yes or no?" #f '(yes-no))
;; Text version, via stty
(define stty
(let ([exe (find-executable-path "stty")])
(λ args (void (apply system* exe args)))))
(define tty-settings (string-trim (with-output-to-string (λ() (stty "-g")))))
(printf "Yes or no? ") (flush-output)
(stty "-icanon" "-echo" "min" "1")
(let loop () (when (char-ready?) (loop)))
(let loop ()
(define ch (read-char))
(case (char-downcase ch)
[(#\y #\Y #\n #\N) (displayln ch) (if (memq ch '(#\y #\Y)) 'yes 'no)]
[else (loop)]))
(stty tty-settings)
</syntaxhighlight>
=={{header|Raku}}==
(formerly Perl 6)
<syntaxhighlight lang="raku" line>my $TTY = open("/dev/tty");
sub prompt-char($prompt) {
ENTER shell "stty raw -echo min 1 time 1";
LEAVE shell "stty sane";
print $prompt;
$TTY.read(1).decode('latin1');
}
say so prompt-char("Y or N? ") ~~ /:i y/;</syntaxhighlight>
=={{header|REXX}}==
===version for all classic REXXes===
This version works with all classic REXXes.
<br><br>REXX (in general) requires the user to press the '''ENTER''' key after entering text.
<br>This is because the original (IBM) REXX was designed and written for a system when all I/O to a user's terminal screen was
<br>in block mode and required the user to press one of the following before any data was sent to the computer:
* the '''ENTER''' key
* a '''PF''' (program function key)
* a '''PA''' (program assist key)
* the '''ATTN''' (attention) key
* possibly some other special key(s)
<br>Note that the above keys may have different names on terminals that emulate an IBM 3270 type terminal (block mode terminals).
<br>Some older Classic REXX interpreters have a keyboard read subroutine (BIF) so that the program can read keyboard keys as
<br>they are pressed (see the other versions below).
<syntaxhighlight lang="rexx">/*REXX program tests for a Y or N key when entered from keyboard after a prompt.*/
do queued(); pull; end /*flush the stack if anything is queued*/
prompt = 'Please enter Y or N for verification:' /*this is the PROMPT message.*/
do until pos(ans,'NY')\==0 & length(ans)==1 /*keep looking for a Y or N answer.*/
say; say prompt /*display blank line; display prompt. */
pull ans /*get the answer(s) and uppercase it.*/
ans=space(ans, 0) /*elide all blanks. */
end /*until*/
/*stick a fork in it, we're all done. */</syntaxhighlight>
===version 1 for PC/REXX and Personal REXX===
This version of a REXX program works with PC/REXX and Personal REXX.
<syntaxhighlight lang="rexx">/*REXX program tests for a Y or N key when entered from keyboard after a prompt.*/
prompt = 'Please enter Y or N for verification:' /*this is the PROMPT message.*/
do until pos(ans, 'NYny') \== 0 /*keep prompting until answer= Y N y n */
say; say prompt /*display blank line; display prompt. */
ans=inKey('wait') /*get the answer(s) from the terminal. */
end /*until*/
/*stick a fork in it, we're all done. */</syntaxhighlight>
===version 2 for PC/REXX and Personal REXX===
This version is the same as above, but has a more idiomatic technique for testing the response.
<syntaxhighlight lang="rexx">/*REXX program tests for a Y or N key when entered from keyboard after a prompt.*/
prompt = 'Please enter Y or N for verification:' /*this is the PROMPT message.*/
do until pos(ans, 'NY')\==0 /*keep prompting 'til user answers Y│N */
say; say prompt /*display blank line; display prompt. */
ans=inKey('wait'); upper ans /*get the answer(s); and uppercase it.*/
end /*until*/
/*stick a fork in it, we're all done. */</syntaxhighlight>
=={{header|Ring}}==
<syntaxhighlight lang="ring">
while true
give c
if c = "Y" see "You said yes!" + nl
but c = "N" see "You said no!" + nl
else see "Try again!" + nl ok
end
</syntaxhighlight>
=={{header|RPL}}==
≪ "Yes or No?" 1 DISP
'''DO'''
'''DO UNTIL''' KEY '''END'''
'''UNTIL''' "YN" SWAP POS '''END'''
"YN" LAST DUP SUB CLMF
≫
´'''TASK'''’ STO
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">
def yesno
begin
system("stty raw -echo")
str = STDIN.getc
ensure
system("stty -raw echo")
end
if str == "Y"
return true
elsif str == "N"
return false
else
raise "Invalid character."
end
end
</syntaxhighlight>
Ruby provides the io/console module since version 2.0:
<syntaxhighlight lang="ruby">
require 'io/console'
def yesno
case $stdin.getch
when "Y" then true
when "N" then false
else raise "Invalid character."
end
end
</syntaxhighlight>
=={{header|Run BASIC}}==
<syntaxhighlight lang="runbasic">[loop] cls ' Clear screen
html "Click Y or N" ' no other options
button #y, "Y", [Y] ' they either click [Y]
button #n, "N", [N] ' or they click [N]
html "<br>";msg$ ' print message showing what they entered
wait
[Y] msg$ = "You entered [Y]es": goto [loop]
[N] msg$ = "You entered [N]o" : goto [loop]
</syntaxhighlight>
=={{header|Rust}}==
{{libheader|Ncurses}}
<syntaxhighlight lang="rust">//cargo-deps: ncurses
extern crate ncurses;
use ncurses::*;
fn main() {
initscr();
loop {
printw("Yes or no? ");
refresh();
match getch() as u8 as char {
'Y'|'y' => {printw("You said yes!");},
'N'|'n' => {printw("You said no!");},
_ => {printw("Try again!\n"); continue;},
}
break
}
refresh();
endwin();
}</syntaxhighlight>
=={{header|Scala}}==
<syntaxhighlight lang="scala"> println(if (scala.io.StdIn.readBoolean) "Yes typed." else "Something else.")</syntaxhighlight>
----
<syntaxhighlight lang="scala">
import java.io.InputStreamReader
val in = new InputStreamReader(System.in)
if (Seq(121, 89, 110, 78).contains(in.read()) ) {println("Yes|No")} else {println("other")}
</syntaxhighlight>
----
<syntaxhighlight lang="scala">
import scala.io.{Source, BufferedSource}
val kbd_In: BufferedSource = Source.stdin
//kbd_In.next()
//res?: Char = 'y' not :String = "y"
if (Seq('y', 'Y', 'n', 'Y').contains(kbd_In.next()) ) {println("Typed y|Y|n|N")} else {println("other key")}
</syntaxhighlight>
=={{header|Seed7}}==
<syntaxhighlight lang="seed7">$ include "seed7_05.s7i";
include "keybd.s7i";
const func boolean: yesOrNo (in string: prompt) is func
result
var boolean: yes is FALSE;
local
var char: answer is ' ';
begin
while inputReady(KEYBOARD) do
ignore(getc(KEYBOARD));
end while;
write(prompt);
repeat
answer := lower(getc(KEYBOARD));
until answer in {'y', 'n'};
yes := answer = 'y';
end func;
const proc: main is func
begin
writeln(yesOrNo("Press Y or N to continue "));
end func;</syntaxhighlight>
=={{header|Sidef}}==
{{trans|Perl}}
<syntaxhighlight lang="ruby">func prompt_yn {
static rk = frequire('Term::ReadKey');
rk.ReadMode(4); # change to raw input mode
var key = '';
while (key !~ /[yn]/i) {
while (rk.ReadKey(-1) != nil) {}; # discard any previous input
print "Type Y/N: ";
say (key = rk.ReadKey(0)); # read a single character
}
rk.ReadMode(0); # reset the terminal to normal mode
return key.uc;
}
var key = prompt_yn();
say "You typed: #{key}";</syntaxhighlight>
{{out}}
<pre>
Type Y/N: a
Type Y/N: b
Type Y/N: c
Type Y/N: y
You typed: Y
</pre>
=={{header|SparForte}}==
As a structured script.
<syntaxhighlight lang="ada">#!/usr/local/bin/spar
pragma annotate( summary, "yorn" );
pragma annotate( description, "Obtain a valid Y or N response from the keyboard. The" );
pragma annotate( description, "keyboard should be flushed, so that any outstanding keypresses" );
pragma annotate( description, "are removed, preventing any existing Y or N keypress from" );
pragma annotate( description, "being evaluated. The response should be obtained as soon as" );
pragma annotate( description, "Y or N are pressed, and there should be no need to press an" );
pragma annotate( description, "enter key. " );
pragma annotate( see_also, "http://rosettacode.org/wiki/Keyboard_Input/Obtain_a_Y_or_N_response" );
pragma annotate( author, "Ken O. Burtch" );
pragma ada_95;
pragma restriction( no_external_commands );
procedure yorn is
answer : character;
begin
put( "Your answer? (Y/N) " );
loop
answer := inkey;
case answer is
when 'Y'|'y' =>
answer := 'Y';
exit;
when 'N'|'n' =>
answer := 'N';
exit;
when others =>
null;
end case;
end loop;
put_line( answer );
end yorn;</syntaxhighlight>
=={{header|Tcl}}==
Using the console (expects U*Xish <tt>stty</tt>)
<syntaxhighlight lang="tcl">proc yesno {{message "Press Y or N to continue"}} {
fconfigure stdin -blocking 0
exec stty raw
read stdin ; # flush
puts -nonewline "${message}: "
flush stdout
while {![eof stdin]} {
set c [string tolower [read stdin 1]]
if {$c eq "y" || $c eq "n"} break
}
puts [string toupper $c]
exec stty -raw
fconfigure stdin -blocking 1
return [expr {$c eq "y"}]
}
set yn [yesno "Do you like programming (Y/N)"]</syntaxhighlight>
Without a console (answer in the global variable yn; this should work in any GUI for which there is a TCL):
<syntaxhighlight lang="tcl">
proc yesno {message} {
toplevel .msg
pack [label .msg.l -text "$message\n (type Y/N)?"]
set ::yn ""
bind .msg <Key-y> {set ::yn "Y"}
bind .msg <Key-n> {set ::yn "N"}
vwait ::yn
destroy .msg
}
yesno "Do you like programming?"
</syntaxhighlight>
=={{header|TXR}}==
This works not only on Unix-like platforms, but also on Microsoft Windows, because TXR is ported to Windows using a [https://www.kylheku.com/cygnal/index.html modified version of Cygwin].
<syntaxhighlight lang="txrlisp">(with-resources ((tio-orig (tcgetattr) (tcsetattr tio-orig)))
(let ((tio (copy tio-orig)))
tio.(go-raw)
(tcsetattr tio tcsaflush) ;; third arg optional, defaults to tcsadrain
(whilet ((k (get-char))
((not (member k '(#\y #\n #\Y #\N))))))))</syntaxhighlight>
The <code>go-raw</code> method on the <code>termios</code> structure only manipulates the structure contents; <code>tcsetattr</code> pushes it down to the TTY driver.
<code>go-raw</code> is defined in the TXR standard library like this:
<syntaxhighlight lang="txrlisp">(defmeth termios go-raw (tio)
tio.(clear-iflags ignbrk brkint parmrk istrip inlcr igncr icrnl ixon)
tio.(clear-oflags opost)
tio.(clear-cflags csize parenb)
tio.(clear-lflags echo echonl icanon isig)
(if (boundp 'iexten)
tio.(clear-lflags iexten))
tio.(set-cflags cs8)
(set tio.[cc vmin] 1)
(set tio.[cc vtime] 0))</syntaxhighlight>
=={{header|UNIX Shell}}==
{{works with|Bourne Again SHell}}
<syntaxhighlight lang="bash">getkey() {
local stty="$(stty -g)"
trap "stty $stty; trap SIGINT; return 128" SIGINT
stty cbreak -echo
local key
while true; do
key=$(dd count=1 2>/dev/null) || return $?
if [ -z "$1" ] || [[ "$key" == [$1] ]]; then
break
fi
done
stty $stty
echo "$key"
return 0
}
yorn() {
echo -n "${1:-Press Y or N to continue: }" >&2
local yorn="$(getkey YyNn)" || return $?
case "$yorn" in
[Yy]) echo >&2 Y; return 0;;
[Nn]) echo >&2 N; return 1;;
esac
}</syntaxhighlight>
Cleaner version using bash built-ins
<syntaxhighlight lang="sh">#!/bin/bash
yorn() {
echo -n "${1:-Press Y or N to continue: }"
shopt -s nocasematch
until [[ "$ans" == [yn] ]]
do
read -s -n1 ans
done
echo "$ans"
shopt -u nocasematch
}
yorn</syntaxhighlight>
=={{header|VB-DOS}}==
<syntaxhighlight lang="vb">OPTION EXPLICIT
DIM T AS INTEGER
T = MSGBOX("Click on yes or no", 4, "Option")
PRINT "The response is ";
IF T = 6 THEN PRINT "yes"; ELSE PRINT "no";
PRINT "."
END</syntaxhighlight>
=={{header|Vedit macro language}}==
<syntaxhighlight lang="vedit">Key_Purge() // flush keyboard buffer
do {
#1 = Get_Key("Are you sure? (Y/N): ") // prompt for a key
#1 &= 0xdf // to upper case
} while (#1 != 'Y' && #1 != 'N') </syntaxhighlight>
=={{header|V (Vlang)}}==
<syntaxhighlight lang="v (vlang)">import term.ui as tui
struct App {
mut:
tui &tui.Context = 0
}
fn event(e &tui.Event, x voidptr) {
mut app := &App(x)
app.tui.clear()
app.tui.set_cursor_position(0, 0)
app.tui.write('V term.input event viewer (type `y`, `Y`, `n`, or `N` to exit)\n\n')
if e.typ == .key_down {
mut cap := ''
if !e.modifiers.is_empty() && e.modifiers.has(.shift) {
cap = 'capital'
}
match e.code {
.y {
app.tui.write('You typed $cap y')
}
.n {
app.tui.write('You typed $cap n')
}
else {
app.tui.write("You didn't type n or y")
}
}
}
app.tui.flush()
if e.typ == .key_down && (e.code == .y || e.code==.n) {
exit(0)
}
}
fn main() {
mut app := &App{}
app.tui = tui.init(
user_data: app
event_fn: event
window_title: 'V term.ui event viewer'
hide_cursor: true
capture_events: true
frame_rate: 60
use_alternate_buffer: false
)
println('V term.input event viewer (type `y`, `Y`, `n`, or `N` to exit)\n\n')
app.tui.run()?
}</syntaxhighlight>
=={{header|Wee Basic}}==
<syntaxhighlight lang="wee basic">print 1 "Enter Y for yes, or N for no. (not case sensitive)"
let loop=0
let keycode=0
while loop=0
let keycode=key()
if keycode=121
let response$="y"
let loop=1
elseif keycode=89
let response$="Y"
let loop=1
elseif keycode=110
let response$="n"
let loop=1
elseif keycode=78
let response$="N"
let loop=1
endif
wend
print 1 "You entered"+response$
end</syntaxhighlight>
=={{header|Wren}}==
<syntaxhighlight lang="wren">import "io" for Stdin, Stdout
Stdin.isRaw = true // input is neither echoed nor buffered in this mode
System.print("Press Y or N")
Stdout.flush()
var byte
while ((byte = Stdin.readByte()) && !"YNyn".bytes.contains(byte)) {}
var yn = String.fromByte(byte)
System.print(yn)
Stdin.isRaw = false</syntaxhighlight>
{{out}}
Sample run:
<pre>
Press Y or N
y
</pre>
=={{header|XPL0}}==
<syntaxhighlight lang="xpl0">include c:\cxpl\codes; \intrinsic 'code' declarations
loop [OpenI(1); \flush any pending keystroke
case ChIn(1) of \get keystroke
^Y,^y: Text(0, "yes");
^N,^n: Text(0, "no");
$1B: quit \Esc key terminates program
other ChOut(0, 7\bel\);
CrLf(0);
]</syntaxhighlight>
=={{header|Z80 Assembly}}==
{{works with|Amstrad CPC}}
This simple template can be <code>CALL</code>ed to wait for a Y/N response and act based on that. This particular template is limited in that the code that gets executed based on the response can't be changed at runtime (at least not without self-modifying code.)
<syntaxhighlight lang="z80">wait_for_key_input:
call &BB06 ;bios call, waits until key is pressed, returns key's ASCII code into A
and %11011111 ;converts to upper case
cp 'Y'
jp z,User_Chose_Yes
cp 'N'
jp z,User_Chose_No
jp wait_for_key_input
User_Chose_Yes:
;your code for what happens when the user types "Y" goes here
ret
User_Chose_No:
;your code for what happens when the user types "N" goes here
ret</syntaxhighlight>
{{omit from|GUISS}}
[[Category:Keyboard input]]
| |||