+'\" t
.\"***************************************************************************
-.\" Copyright (c) 1998-2005,2010 Free Software Foundation, Inc. *
+.\" Copyright 2018-2023,2024 Thomas E. Dickey *
+.\" Copyright 1998-2016,2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" copy of this software and associated documentation files (the *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_inopts.3x,v 1.15 2010/12/04 18:40:45 tom Exp $
-.TH curs_inopts 3X ""
-.na
-.hy 0
+.\" $Id: curs_inopts.3x,v 1.66 2024/04/13 22:20:29 tom Exp $
+.TH curs_inopts 3X 2024-04-13 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
+.ie \n(.g \{\
+.ds `` \(lq
+.ds '' \(rq
+.\}
+.el \{\
+.ie t .ds `` ``
+.el .ds `` ""
+.ie t .ds '' ''
+.el .ds '' ""
+.\}
.SH NAME
-\fBcbreak\fR,
-\fBnocbreak\fR,
-\fBecho\fR,
-\fBnoecho\fR,
-\fBhalfdelay\fR,
-\fBintrflush\fR,
-\fBkeypad\fR,
-\fBmeta\fR,
-\fBnodelay\fR,
-\fBnotimeout\fR,
-\fBraw\fR,
-\fBnoraw\fR,
-\fBnoqiflush\fR,
-\fBqiflush\fR,
-\fBtimeout\fR,
-\fBwtimeout\fR,
-\fBtypeahead\fR \- \fBcurses\fR input options
-.ad
-.hy
+\fB\%cbreak\fP,
+\fB\%echo\fP,
+\fB\%halfdelay\fP,
+\fB\%intrflush\fP,
+\fB\%is_cbreak\fP,
+\fB\%is_echo\fP,
+\fB\%is_nl\fP,
+\fB\%is_raw\fP,
+\fB\%keypad\fP,
+\fB\%meta\fP,
+\fB\%nl\fP,
+\fB\%nocbreak\fP,
+\fB\%nodelay\fP,
+\fB\%noecho\fP,
+\fB\%nonl\fP,
+\fB\%noqiflush\fP,
+\fB\%noraw\fP,
+\fB\%notimeout\fP,
+\fB\%qiflush\fP,
+\fB\%raw\fP,
+\fB\%timeout\fP,
+\fB\%wtimeout\fP,
+\fB\%typeahead\fP \-
+get and set \fIcurses\fR terminal input options
.SH SYNOPSIS
-\fB#include <curses.h>\fR
-.PP
-\fBint cbreak(void);\fR
-.br
-\fBint nocbreak(void);\fR
-.br
-\fBint echo(void);\fR
-.br
-\fBint noecho(void);\fR
-.br
-\fBint halfdelay(int tenths);\fR
-.br
-\fBint intrflush(WINDOW *win, bool bf);\fR
-.br
-\fBint keypad(WINDOW *win, bool bf);\fR
-.br
-\fBint meta(WINDOW *win, bool bf);\fR
-.br
-\fBint nodelay(WINDOW *win, bool bf);\fR
-.br
-\fBint raw(void);\fR
-.br
-\fBint noraw(void);\fR
-.br
-\fBvoid noqiflush(void);\fR
-.br
-\fBvoid qiflush(void);\fR
-.br
-\fBint notimeout(WINDOW *win, bool bf);\fR
-.br
-\fBvoid timeout(int delay);\fR
-.br
-\fBvoid wtimeout(WINDOW *win, int delay);\fR
-.br
-\fBint typeahead(int fd);\fR
-.br
-.SH DESCRIPTION
-Normally, the tty driver buffers typed characters until a newline or carriage
-return is typed. The \fBcbreak\fR routine disables line buffering and
-erase/kill character-processing (interrupt and flow control characters are
-unaffected), making characters typed by the user immediately available to the
-program. The \fBnocbreak\fR routine returns the terminal to normal (cooked)
-mode.
+.nf
+\fB#include <curses.h>
+.PP
+\fBint cbreak(void);
+\fBint nocbreak(void);
+.PP
+\fBint echo(void);
+\fBint noecho(void);
+.PP
+\fBint intrflush(WINDOW *\fIwin\fP, bool \fIbf\fP);
+\fBint keypad(WINDOW *\fIwin\fP, bool \fIbf\fP);
+\fBint meta(WINDOW *\fIwin\fP, bool \fIbf\fP);
+\fBint nodelay(WINDOW *\fIwin\fP, bool \fIbf\fP);
+\fBint notimeout(WINDOW *\fIwin\fP, bool \fIbf\fP);
+.PP
+\fBint nl(void);
+\fBint nonl(void);
+.PP
+\fBint raw(void);
+\fBint noraw(void);
+.PP
+\fBvoid qiflush(void);
+\fBvoid noqiflush(void);
+.PP
+\fBint halfdelay(int \fItenths\fP);
+\fBvoid timeout(int \fIdelay\fP);
+\fBvoid wtimeout(WINDOW *\fIwin\fP, int \fIdelay\fP);
.PP
-Initially the terminal may or may not be in \fBcbreak\fR mode, as the mode is
-inherited; therefore, a program should call \fBcbreak\fR or \fBnocbreak\fR
-explicitly. Most interactive programs using \fBcurses\fR set the \fBcbreak\fR
-mode. Note that \fBcbreak\fR overrides \fBraw\fR.
-[See \fBcurs_getch\fR(3X) for a
-discussion of how these routines interact with \fBecho\fR and \fBnoecho\fR.]
-.PP
-The \fBecho\fR and \fBnoecho\fR routines control whether characters typed by
-the user are echoed by \fBgetch\fR as they are typed. Echoing by the tty
-driver is always disabled, but initially \fBgetch\fR is in echo mode, so
-characters typed are echoed. Authors of most interactive programs prefer to do
-their own echoing in a controlled area of the screen, or not to echo at all, so
-they disable echoing by calling \fBnoecho\fR.
-[See \fBcurs_getch\fR(3X) for a
-discussion of how these routines interact with \fBcbreak\fR and
-\fBnocbreak\fR.]
-.PP
-The \fBhalfdelay\fR routine is used for half-delay mode, which is similar to
-\fBcbreak\fR mode in that characters typed by the user are immediately
-available to the program. However, after blocking for \fItenths\fR tenths of
-seconds, ERR is returned if nothing has been typed. The value of \fBtenths\fR
-must be a number between 1 and 255. Use \fBnocbreak\fR to leave half-delay
+\fBint typeahead(int \fIfd\fP);
+.PP
+\fI/* extensions */
+\fBint is_cbreak(void);
+\fBint is_echo(void);
+\fBint is_nl(void);
+\fBint is_raw(void);
+.fi
+.SH DESCRIPTION
+.I \%ncurses
+provides several functions that let an application change the way input
+from the terminal is handled.
+Some are global,
+applying to all windows.
+Others apply only to a specific window.
+Window-specific settings are not automatically applied to new or derived
+windows.
+An application must apply these to each window if the same behavior is
+desired.
+.\"
+.SS "cbreak, nocbreak"
+Normally,
+the terminal driver buffers typed characters until a newline or carriage
+return is typed.
+The \fB\%cbreak\fP routine disables line buffering and
+erase/kill character-processing
+(interrupt and flow control characters are unaffected),
+making characters typed by the user immediately available to the
+program.
+The \fB\%nocbreak\fP routine returns the terminal to normal (cooked)
mode.
.PP
-If the \fBintrflush\fR option is enabled, (\fIbf\fR is \fBTRUE\fR), when an
-interrupt key is pressed on the keyboard (interrupt, break, quit) all output in
-the tty driver queue will be flushed, giving the effect of faster response to
-the interrupt, but causing \fBcurses\fR to have the wrong idea of what is on
-the screen. Disabling (\fIbf\fR is \fBFALSE\fR), the option prevents the
-flush. The default for the option is inherited from the tty driver settings.
-The window argument is ignored.
-.PP
-The \fBkeypad\fR option enables the keypad of the user's terminal. If
-enabled (\fIbf\fR is \fBTRUE\fR), the user can press a function key
-(such as an arrow key) and \fBwgetch\fR returns a single value
-representing the function key, as in \fBKEY_LEFT\fR. If disabled
-(\fIbf\fR is \fBFALSE\fR), \fBcurses\fR does not treat function keys
-specially and the program has to interpret the escape sequences
-itself. If the keypad in the terminal can be turned on (made to
-transmit) and off (made to work locally), turning on this option
-causes the terminal keypad to be turned on when \fBwgetch\fR is
-called. The default value for keypad is false.
-.PP
-Initially, whether the terminal returns 7 or 8 significant bits on
-input depends on the control mode of the tty driver [see termio(7)].
-To force 8 bits to be returned, invoke \fBmeta\fR(\fIwin\fR,
-\fBTRUE\fR); this is equivalent, under POSIX, to setting the CS8 flag
-on the terminal. To force 7 bits to be returned, invoke
-\fBmeta\fR(\fIwin\fR, \fBFALSE\fR); this is equivalent, under POSIX,
-to setting the CS7 flag on the terminal. The window argument,
-\fIwin\fR, is always ignored. If the terminfo capabilities \fBsmm\fR
-(meta_on) and \fBrmm\fR (meta_off) are defined for the terminal,
-\fBsmm\fR is sent to the terminal when \fBmeta\fR(\fIwin\fR,
-\fBTRUE\fR) is called and \fBrmm\fR is sent when \fBmeta\fR(\fIwin\fR,
-\fBFALSE\fR) is called.
-.PP
-The \fBnodelay\fR option causes \fBgetch\fR to be a non-blocking call.
-If no input is ready, \fBgetch\fR returns \fBERR\fR. If disabled
-(\fIbf\fR is \fBFALSE\fR), \fBgetch\fR waits until a key is pressed.
-.PP
-While interpreting an input escape sequence, \fBwgetch\fR sets a timer
-while waiting for the next character. If \fBnotimeout(\fR\fIwin\fR,
-\fBTRUE\fR) is called, then \fBwgetch\fR does not set a timer. The
-purpose of the timeout is to differentiate between sequences received
-from a function key and those typed by a user.
-.PP
-The \fBraw\fR and \fBnoraw\fR routines place the terminal into or out of raw
-mode. Raw mode is similar to \fBcbreak\fR mode, in that characters typed are
-immediately passed through to the user program. The differences are that in
-raw mode, the interrupt, quit, suspend, and flow control characters are all
-passed through uninterpreted, instead of generating a signal. The behavior of
-the BREAK key depends on other bits in the tty driver that are not set by
-\fBcurses\fR.
-.PP
-When the \fBnoqiflush\fR routine is used, normal flush of input and
-output queues associated with the \fBINTR\fR, \fBQUIT\fR and
-\fBSUSP\fR characters will not be done [see termio(7)]. When
-\fBqiflush\fR is called, the queues will be flushed when these control
-characters are read. You may want to call \fBnoqiflush()\fR in a signal
-handler if you want output to continue as though the interrupt
-had not occurred, after the handler exits.
-.PP
-The \fBtimeout\fR and \fBwtimeout\fR routines set blocking or
-non-blocking read for a given window. If \fIdelay\fR is negative,
-blocking read is used (i.e., waits indefinitely for
-input). If \fIdelay\fR is zero, then non-blocking read is used
-(i.e., read returns \fBERR\fR if no input is waiting). If
-\fIdelay\fR is positive, then read blocks for \fIdelay\fR
-milliseconds, and returns \fBERR\fR if there is still no input.
-Hence, these routines provide the same functionality as \fBnodelay\fR,
+Initially the terminal may or may not be in \fB\%cbreak\fP mode,
+as the mode is inherited;
+therefore,
+a program should call \fB\%cbreak\fP or \fB\%nocbreak\fP explicitly.
+Most interactive programs using
+.I curses
+set the \fB\%cbreak\fP mode.
+Note that \fB\%cbreak\fP overrides \fBraw\fP.
+[See \fB\%curs_getch\fP(3X) for a discussion of how these routines
+interact with \fBecho\fP and \fB\%noecho\fP.]
+.\"
+.SS "echo, noecho"
+The \fBecho\fP and \fB\%noecho\fP routines control whether characters
+typed by the user are echoed by \fB\%getch\fP(3X) as they are typed.
+Echoing by the terminal driver is always disabled,
+but initially \fB\%getch\fP is in echo mode,
+so characters typed are echoed.
+Authors of most interactive programs prefer to do
+their own echoing in a controlled area of the screen,
+or not to echo at all,
+so they disable echoing by calling \fB\%noecho\fP.
+[See \fB\%curs_getch\fP(3X) for a
+discussion of how these routines interact with \fB\%cbreak\fP and
+\fB\%nocbreak\fP.]
+.\"
+.SS halfdelay
+The \fB\%halfdelay\fP routine is used for half-delay mode,
+which is similar to \fB\%cbreak\fP mode in that characters typed by the
+user are immediately available to the program.
+However,
+after blocking for \fItenths\fP tenths of seconds,
+\fBERR\fP is returned if nothing has been typed.
+The value of \fItenths\fP must be a number between 1 and 255.
+Use \fB\%nocbreak\fP to leave half-delay mode.
+.\"
+.SS intrflush
+If the \fB\%intrflush\fP option is enabled
+.RI ( bf
+is
+.BR TRUE ),
+and an interrupt key is pressed on the keyboard
+(interrupt,
+break,
+quit),
+all output in the terminal driver queue is flushed,
+giving the effect of faster response to the interrupt,
+but causing
+.I curses
+to have the wrong idea of what is on the screen.
+Disabling the option
+.RI ( bf
+is
+.BR FALSE ),
+prevents the flush.
+The default for the option is inherited from the terminal driver
+settings.
+The
+.I win
+argument is ignored.
+.\"
+.SS keypad
+The \fB\%keypad\fP option enables the keypad of the user's terminal.
+If
+enabled
+.RI ( bf
+is
+.BR TRUE ),
+the user can press a function key
+(such as an arrow key)
+and \fB\%wgetch\fP(3X) returns a single value representing the function
+key,
+as in \fB\%KEY_LEFT\fP.
+If disabled
+(\fIbf\fP is \fBFALSE\fP),
+.I curses
+does not treat function keys specially and the program has to interpret
+the escape sequences itself.
+If the keypad in the terminal can be turned on
+(made to transmit)
+and off
+(made to work locally),
+turning on this option causes the terminal keypad to be turned on when
+\fB\%wgetch\fP(3X) is called.
+The default value for keypad is \fBFALSE\fP.
+.\"
+.SS meta
+Initially,
+whether the terminal returns 7 or 8 significant bits on input depends on
+the control mode of the terminal driver [see \fI\%termios\fP(3)].
+To force 8 bits to be returned,
+invoke
+\fBmeta\fP(\fIwin\fP, \fBTRUE\fP);
+this is equivalent,
+under POSIX,
+to setting the CS8 flag on the terminal.
+To force 7 bits to be returned,
+invoke
+\fBmeta\fP(\fIwin\fP, \fBFALSE\fP);
+this is equivalent,
+under POSIX,
+to setting the CS7 flag on the terminal.
+The window argument,
+.IR win ,
+is always ignored.
+If the terminfo capabilities
+\fBsmm\fP (meta_on) and
+\fBrmm\fP (meta_off) are defined for the terminal,
+\fBsmm\fP is sent to the terminal when
+\fBmeta\fP(\fIwin\fP, \fBTRUE\fP)
+is called and \fBrmm\fP is sent when
+\fBmeta\fP(\fIwin\fP, \fBFALSE\fP) is called.
+.\"
+.SS "nl, nonl"
+The \fBnl\fP and \fBnonl\fP routines control whether the underlying
+display device translates the return key into newline on input.
+.\"
+.SS nodelay
+The \fB\%nodelay\fP option causes \fB\%getch\fP to be a non-blocking
+call.
+If no input is ready,
+\fB\%getch\fP returns \fBERR\fP.
+If disabled
+.RI ( bf
+is
+.BR FALSE ),
+\fB\%getch\fP waits until a key is pressed.
+.SS notimeout
+When interpreting an escape sequence,
+\fB\%wgetch\fP(3X) sets a timer
+while waiting for the next character.
+If
+\fB\%notimeout(\fIwin\fR, \fBTRUE\fP)
+is called,
+then \fB\%wgetch\fP does not set a timer.
+The purpose of the timeout is to distinguish sequences produced by a
+function key from those typed by a user.
+.\"
+.SS "raw, noraw"
+The \fBraw\fP and \fB\%noraw\fP routines place the terminal into or out
+of raw mode.
+Raw mode is similar to \fB\%cbreak\fP mode,
+in that characters typed are immediately passed through to the user
+program.
+The differences are that in raw mode,
+the interrupt,
+quit,
+suspend,
+and flow control characters are all
+passed through uninterpreted,
+instead of generating a signal.
+The behavior of the BREAK key depends on other bits in the terminal
+driver that are not set by
+.IR curses .
+.\"
+.SS "qiflush, nqiflush"
+When the \fB\%noqiflush\fP routine is used,
+normal flush of input and output queues associated with the \fBINTR\fP,
+\fBQUIT\fP and \fBSUSP\fP characters will not be done
+[see \fB\%termios\fP(3)].
+When
+\fB\%qiflush\fP is called,
+the queues will be flushed when these control characters are read.
+You may want to call \fB\%noqiflush\fP in a signal handler if you want
+output to continue as though the interrupt had not occurred,
+after the handler exits.
+.\"
+.SS "timeout, wtimeout"
+The \fB\%timeout\fP and \fB\%wtimeout\fP routines set blocking or
+non-blocking read for a given window.
+If \fIdelay\fP is negative,
+a blocking read is used
+(i.e.,
+waits indefinitely for input).
+If \fIdelay\fP is zero,
+then a non-blocking read is used
+(i.e.,
+.I read
+returns \fBERR\fP if no input is waiting).
+If
+\fIdelay\fP is positive,
+then
+.I read
+blocks for \fIdelay\fP milliseconds,
+and returns \fBERR\fP if there is still no input.
+Hence,
+these routines provide the same functionality as \fB\%nodelay\fP,
plus the additional capability of being able to block for only
-\fIdelay\fR milliseconds (where \fIdelay\fR is positive).
-.PP
-The \fBcurses\fR library does ``line-breakout optimization'' by looking for
-typeahead periodically while updating the screen. If input is found,
-and it is coming from a tty, the current update is postponed until
-\fBrefresh\fR or \fBdoupdate\fR is called again. This allows faster
-response to commands typed in advance. Normally, the input FILE
-pointer passed to \fBnewterm\fR, or \fBstdin\fR in the case that
-\fBinitscr\fR was used, will be used to do this typeahead checking.
-The \fBtypeahead\fR routine specifies that the file descriptor
-\fIfd\fR is to be used to check for typeahead instead. If \fIfd\fR is
-\-1, then no typeahead checking is done.
+\fIdelay\fP milliseconds
+(where \fIdelay\fP is positive).
+.\"
+.SS typeahead
+.I curses
+does \*(``line-breakout optimization\*('' by looking for typeahead
+periodically while updating the screen.
+If input is found,
+and it is coming from a terminal,
+the current update is postponed until
+\fB\%refresh\fP(3X) or \fB\%doupdate\fP is called again.
+This allows faster response to commands typed in advance.
+Normally,
+the input
+.I FILE
+pointer passed to \fB\%newterm\fP,
+or \fBstdin\fP in the case that \fB\%initscr\fP was used,
+will be used to do this typeahead checking.
+The \fB\%typeahead\fP routine specifies that the file descriptor
+\fIfd\fP is to be used to check for typeahead instead.
+If \fIfd\fP is
+\-1,
+then no typeahead checking is done.
+.\"
.SH RETURN VALUE
-All routines that return an integer return \fBERR\fR upon failure and OK (SVr4
-specifies only "an integer value other than \fBERR\fR") upon successful
-completion, unless otherwise noted in the preceding routine descriptions.
+All routines that return an integer return \fBERR\fP upon failure and
+\fBOK\fP
+(SVr4 specifies only \*(``an integer value other than \fBERR\fP\*('')
+upon successful completion,
+unless otherwise noted in the preceding routine descriptions.
.PP
-X/Open does not define any error conditions.
+X/Open Curses does not specify any error conditions.
In this implementation,
functions with a window parameter will return an error if it is null.
-Any function will also return an error if the terminal was not initialized.
+Any function will also return an error if the terminal was not
+initialized.
Also,
-.RS
+.RS 3
.TP 5
-\fBhalfdelay\fP
+\fB\%halfdelay\fP
returns an error
if its parameter is outside the range 1..255.
.RE
-.SH PORTABILITY
-These functions are described in the XSI Curses standard, Issue 4.
-.PP
-The ncurses library obeys the XPG4 standard and the historical practice of the
-AT&T curses implementations, in that the echo bit is cleared when curses
-initializes the terminal state. BSD curses differed from this slightly; it
-left the echo bit on at initialization, but the BSD \fBraw\fR call turned it
-off as a side-effect. For best portability, set echo or noecho explicitly
-just after initialization, even if your program remains in cooked mode.
.SH NOTES
-Note that \fBecho\fR, \fBnoecho\fR, \fBhalfdelay\fR, \fBintrflush\fR,
-\fBmeta\fR, \fBnodelay\fR, \fBnotimeout\fR, \fBnoqiflush\fR,
-\fBqiflush\fR, \fBtimeout\fR, and \fBwtimeout\fR may be macros.
-.PP
-The \fBnoraw\fR and \fBnocbreak\fR calls follow historical practice in that
-they attempt to restore to normal (`cooked') mode from raw and cbreak modes
-respectively. Mixing raw/noraw and cbreak/nocbreak calls leads to tty driver
-control states that are hard to predict or understand; it is not recommended.
+\fBecho\fP,
+\fB\%noecho\fP,
+\fB\%halfdelay\fP,
+\fB\%intrflush\fP,
+\fBmeta\fP,
+\fBnl\fP,
+\fBnonl\fP,
+\fB\%nodelay\fP,
+\fB\%notimeout\fP,
+\fB\%noqiflush\fP,
+\fB\%qiflush\fP,
+\fB\%timeout\fP,
+and
+\fB\%wtimeout\fP
+may be implemented as macros.
+.PP
+\fB\%noraw\fP and \fB\%nocbreak\fP follow historical practice in that
+they attempt to restore normal (\*(``cooked\*('') mode
+from raw and cbreak modes respectively.
+Mixing \fBraw\fP/\fB\%noraw\fP and \fB\%cbreak\fP/\fB\%nocbreak\fP calls
+leads to terminal driver control states that are hard to predict or
+understand;
+doing so is not recommended.
+.SH EXTENSIONS
+.I \%ncurses
+provides four \*(``is_\*('' functions that may be used to detect if the
+corresponding flags were set or reset.
+.PP
+.TS
+center;
+Lb Lb Lb
+L L L .
+Query Set Reset
+_
+is_cbreak cbreak nocbreak
+is_echo echo noecho
+is_nl nl nonl
+is_raw raw noraw
+.TE
+.PP
+In each case,
+the function returns
+.TP 4 \" "-1" + 2n
+1
+if the flag is set,
+.TP
+0
+if the flag is reset,
+or
+.TP
+\-1
+if the library is not initialized.
+.PP
+They were designed for
+\fB\%ncurses\fP(3X),
+and are not found in SVr4
+.IR curses ,
+4.4BSD
+.IR curses ,
+or any other previous
+.I curses
+implementation.
+.SH PORTABILITY
+Applications employing
+.I \%ncurses
+extensions should condition their use on the visibility of the
+.B \%NCURSES_VERSION
+preprocessor macro.
+.PP
+Except as noted in section \*(``EXTENSIONS\*('' above,
+X/Open Curses, Issue 4, Version 2 describes these functions.
+.PP
+.I \%ncurses
+follows X/Open Curses
+and the historical practice of AT&T
+.I curses
+implementations,
+in that the echo bit is cleared when
+.I curses
+initializes the terminal state.
+BSD
+.I curses
+differed from this slightly;
+it left the echo bit on at initialization,
+but the BSD \fBraw\fP call turned it off as a side effect.
+For best portability,
+set \fBecho\fP or \fB\%noecho\fP explicitly just after initialization,
+even if your program remains in cooked mode.
+.PP
+X/Open Curses is ambiguous regarding whether \fBraw\fP should disable
+the CR/LF translations controlled by \fBnl\fP and \fBnonl\fP.
+BSD
+.I curses
+did turn off these translations;
+AT&T
+.I curses
+(at least as late as SVr1)
+did not.
+.I \%ncurses
+does so,
+on the assumption that a programmer requesting raw input wants a clean
+(ideally,
+8-bit clean)
+connection that the operating system will not alter.
+.PP
+When \fB\%keypad\fP is first enabled,
+.I \%ncurses
+loads the key definitions for the current terminal description.
+If the terminal description includes extended string capabilities,
+e.g.,
+from using the
+.B \-x
+option of \fB\%@TIC@\fP,
+then
+.I \%ncurses
+also defines keys for the capabilities whose names begin with
+\*(``k\*(''.
+The corresponding keycodes are generated and
+(depending on previous loads of terminal descriptions)
+may differ from one execution of a program to the next.
+The generated keycodes are recognized by the \fB\%keyname\fP(3X)
+function
+(which will then return a name beginning with \*(``k\*('' denoting the
+terminfo capability name rather than \*(``K\*('',
+used for
+.I curses
+key names).
+On the other hand,
+an application can use \fB\%define_key\fP(3X) to establish
+a specific keycode for a given string.
+This makes it possible for an application to check for an extended
+capability's presence with \fB\%tigetstr\fP,
+and reassign the keycode to match its own needs.
+.PP
+Low-level applications can use \fB\%tigetstr\fP to obtain the definition
+of any particular string capability.
+Higher-level applications which use the
+.I curses
+\fB\%wgetch\fP and similar functions to return keycodes rely upon the
+order in which the strings are loaded.
+If more than one key definition has the same string value,
+then \fB\%wgetch\fP can return only one keycode.
+Most
+.I curses
+implementations
+(including
+.IR \%ncurses )
+load key definitions in the order
+defined by the array of string capability names.
+The last key to be loaded determines the keycode which will be returned.
+In
+.IR \%ncurses ,
+you may also have extended capabilities interpreted as key definitions.
+These are loaded after the predefined keys,
+and if a capability's value is the same as a previously-loaded
+key definition,
+the later definition is the one used.
+.SH HISTORY
+Formerly,
+.I \%ncurses
+used
+.B \%nl
+and
+.B \%nonl
+to control the conversion of newlines to carriage return/line feed
+on output as well as input.
+X/Open Curses documents the use of these functions only for input.
+This difference arose from converting the
+.I \%pcurses
+source (1986),
+which used
+\fI\%ioctl\fP(2) calls and the
+.I \%sgttyb
+structure,
+to
+.I \%termios
+(the POSIX terminal API).
+In the former,
+both input and output were controlled via a single option
+.BR \%CRMOD ,
+while the latter separates these features.
+Because that conversion interferes with output optimization,
+.I \%ncurses
+6.2 (2020) amended
+.B \%nl
+and
+.B \%nonl
+to eliminate their effect on output.
.SH SEE ALSO
-\fBcurses\fR(3X), \fBcurs_getch\fR(3X), \fBcurs_initscr\fR(3X), \fBtermio\fR(7)
+\fB\%curses\fP(3X),
+\fB\%curs_getch\fP(3X),
+\fB\%curs_initscr\fP(3X),
+\fB\%curs_util\fP(3X),
+\fB\%define_key\fP(3X),
+\fB\%termios\fP(3)
projects / ncurses.git / blobdiff