'\" t
.\"***************************************************************************
-.\" Copyright (c) 1998-2014,2015 Free Software Foundation, Inc. *
+.\" Copyright 2018-2020,2021 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_getch.3x,v 1.41 2015/07/16 09:29:33 tom Exp $
+.\" $Id: curs_getch.3x,v 1.61 2021/12/25 21:49:32 tom Exp $
.TH curs_getch 3X ""
.na
.hy 0
+.ie \n(.g .ds `` \(lq
+.el .ds `` ``
+.ie \n(.g .ds '' \(rq
+.el .ds '' ''
.de bP
-.IP \(bu 4
+.ie n .IP \(bu 4
+.el .IP \(bu 2
..
.SH NAME
-\fBgetch\fR,
-\fBwgetch\fR,
-\fBmvgetch\fR,
-\fBmvwgetch\fR,
-\fBungetch\fR,
-\fBhas_key\fR \- get (or push back) characters from \fBcurses\fR terminal keyboard
+\fBgetch\fP,
+\fBwgetch\fP,
+\fBmvgetch\fP,
+\fBmvwgetch\fP,
+\fBungetch\fP,
+\fBhas_key\fP \- get (or push back) characters from \fBcurses\fP terminal keyboard
.ad
.hy
.SH SYNOPSIS
-\fB#include <curses.h>\fR
+\fB#include <curses.h>\fP
.PP
-\fBint getch(void);\fR
+\fBint getch(void);\fP
.br
-\fBint wgetch(WINDOW *win);\fR
-.br
-\fBint mvgetch(int y, int x);\fR
-.br
-\fBint mvwgetch(WINDOW *win, int y, int x);\fR
+\fBint wgetch(WINDOW *\fP\fIwin);\fP
+.sp
+\fBint mvgetch(int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fP
.br
-\fBint ungetch(int ch);\fR
+\fBint mvwgetch(WINDOW *\fP\fIwin\fP\fB, int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fP
+.sp
+\fBint ungetch(int \fP\fIch\fP\fB);\fP
+.sp
+/* extension */
.br
-\fBint has_key(int ch);\fR
+\fBint has_key(int \fP\fIch\fP\fB);\fP
.br
.SH DESCRIPTION
.SS Reading characters
-The \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR and \fBmvwgetch\fR, routines read
+The \fBgetch\fP, \fBwgetch\fP, \fBmvgetch\fP and \fBmvwgetch\fP, routines read
a character from the window.
-In no-delay mode, if no input is waiting, the value \fBERR\fR is returned.
+In no-delay mode, if no input is waiting, the value \fBERR\fP is returned.
In delay mode, the program waits until the system
passes text through to the program.
-Depending on the setting of \fBcbreak\fR,
+Depending on the setting of \fBcbreak\fP,
this is after one character (cbreak mode),
or after the first newline (nocbreak mode).
In half-delay mode,
the program waits until a character is typed or the
specified timeout has been reached.
.PP
-If \fBecho\fR is enabled, and the window is not a pad,
+If \fBecho\fP is enabled, and the window is not a pad,
then the character will also be echoed into the
designated window according to the following rules:
.bP
If the character is the current erase character, left arrow, or backspace,
the cursor is moved one space to the left and that screen position is erased
-as if \fBdelch\fR had been called.
+as if \fBdelch\fP had been called.
.bP
-If the character value is any other \fBKEY_\fR define, the user is alerted
-with a \fBbeep\fR call.
+If the character value is any other \fBKEY_\fP define, the user is alerted
+with a \fBbeep\fP call.
.bP
If the character is a carriage-return,
and if \fBnl\fP is enabled,
Otherwise the character is simply output to the screen.
.PP
If the window is not a pad, and it has been moved or modified since the last
-call to \fBwrefresh\fR, \fBwrefresh\fR will be called before another character
+call to \fBwrefresh\fP, \fBwrefresh\fP will be called before another character
is read.
.SS Keypad mode
.PP
-If \fBkeypad\fR is \fBTRUE\fR, and a function key is pressed, the token for
-that function key is returned instead of the raw characters.
-Possible function
-keys are defined in \fB<curses.h>\fR as macros with values outside the range
-of 8-bit characters whose names begin with \fBKEY_\fR.
+If \fBkeypad\fP is \fBTRUE\fP, and a function key is pressed, the token for
+that function key is returned instead of the raw characters:
+.bP
+The predefined function
+keys are listed in \fB<curses.h>\fP as macros with values outside the range
+of 8-bit characters.
+Their names begin with \fBKEY_\fP.
+.bP
+Other (user-defined) function keys which may be defined
+using \fBdefine_key\fP(3X)
+have no names, but also are expected to have values outside the range of
+8-bit characters.
+.PP
Thus, a variable
intended to hold the return value of a function key must be of short size or
larger.
.PP
When a character that could be the beginning of a function key is received
(which, on modern terminals, means an escape character),
-\fBcurses\fR sets a timer.
+\fBcurses\fP sets a timer.
If the remainder of the sequence does not come in within the designated
time, the character is passed through;
otherwise, the function key value is returned.
For this reason, many terminals experience a delay between the time
a user presses the escape key and the escape is returned to the program.
+.PP
+In \fBncurses\fP, the timer normally expires after
+the value in \fBESCDELAY\fP (see \fBcurs_variables\fP(3X)).
+If \fBnotimeout\fP is \fBTRUE\fP, the timer does not expire;
+it is an infinite (or very large) value.
+Because function keys usually begin with an escape character,
+the terminal may appear to hang in notimeout mode after pressing the escape key
+until another key is pressed.
.SS Ungetting characters
.PP
-The \fBungetch\fR routine places \fIch\fR back onto the input queue to be
-returned by the next call to \fBwgetch\fR.
+The \fBungetch\fP routine places \fIch\fP back onto the input queue to be
+returned by the next call to \fBwgetch\fP.
There is just one input queue for all windows.
.PP
-.SS Function Keys
-The following function keys, defined in \fB<curses.h>\fR, might be returned by
-\fBgetch\fR if \fBkeypad\fR has been enabled.
-Note that not all of these are
-necessarily supported on any particular terminal.
+.SS Predefined key-codes
+The following special keys are defined in \fB<curses.h>\fP.
+.bP
+Except for the special case \fBKEY_RESIZE\fP,
+it is necessary to enable \fBkeypad\fP for \fBgetch\fP to return these codes.
+.bP
+Not all of these are necessarily supported on any particular terminal.
+.bP
+The naming convention may seem obscure, with some apparent
+misspellings (such as \*(``RSUME\*('' for \*(``resume\*('').
+The names correspond to the long terminfo capability names for the keys,
+and were defined long ago, in the 1980s.
.PP
.TS
center tab(/) ;
l l .
-\fIName\fR/\fIKey\fR \fIname\fR
+\fBName\fP/\fBKey\fP \fBname\fP
_
KEY_BREAK/Break key
KEY_DOWN/The four arrow keys ...
KEY_F0/T{
Function keys; space for 64 keys is reserved.
T}
-KEY_F(\fIn\fR)/T{
-For 0 \(<= \fIn\fR \(<= 63
+KEY_F(\fIn\fP)/T{
+For 0 \(<= \fIn\fP \(<= 63
T}
KEY_DL/Delete line
KEY_IL/Insert line
.TE
.PP
Keypad is arranged like this:
-.sp
+.br
.TS
center allbox tab(/) ;
c c c .
-\fBA1\fR/\fBup\fR/\fBA3\fR
-\fBleft\fR/\fBB2\fR/\fBright\fR
-\fBC1\fR/\fBdown\fR/\fBC3\fR
+\fBA1\fP/\fBup\fP/\fBA3\fP
+\fBleft\fP/\fBB2\fP/\fBright\fP
+\fBC1\fP/\fBdown\fP/\fBC3\fP
.TE
.sp
-The \fBhas_key\fR routine takes a key value from the above list, and
+A few of these predefined values do \fInot\fP correspond to a real key:
+.bP
+.B KEY_RESIZE
+is returned when the \fBSIGWINCH\fP signal has been detected
+(see \fBinitscr\fP(3X) and \fBresizeterm\fP(3X)).
+This code is returned whether or not \fBkeypad\fP has been enabled.
+.bP
+.B KEY_MOUSE
+is returned for mouse-events (see \fBcurs_mouse\fP(3X)).
+This code relies upon whether or not \fBkeypad\fP(3X) has been enabled,
+because (e.g., with \fBxterm\fP(1) mouse prototocol) ncurses must
+read escape sequences,
+just like a function key.
+.SS Testing key-codes
+.PP
+The \fBhas_key\fP routine takes a key-code value from the above list, and
returns \fBTRUE\fP or \fBFALSE\fP according to whether
the current terminal type recognizes a key with that value.
-Note that a few values do not correspond to a real key,
-e.g., \fBKEY_RESIZE\fP and \fBKEY_MOUSE\fP.
-See \fBinitscr\fP(3X) and \fBresizeterm\fR(3X) for more details about \fBKEY_RESIZE\fP, and
-\fBcurs_mouse\fR(3X) for a discussion of \fBKEY_MOUSE\fP.
+.PP
+The library also supports these extensions:
+.RS 3
+.TP 5
+.B define_key
+defines a key-code for a given string (see \fBdefine_key\fP(3X)).
+.TP 5
+.B key_defined
+checks if there is a key-code defined for a given
+string (see \fBkey_defined\fP(3X)).
+.RE
.PP
.SH RETURN VALUE
-All routines return the integer \fBERR\fR upon failure and an integer value
-other than \fBERR\fR (\fBOK\fR in the case of ungetch()) upon successful
+All routines return the integer \fBERR\fP upon failure and an integer value
+other than \fBERR\fP (\fBOK\fP in the case of \fBungetch\fP) upon successful
completion.
.RS 3
.TP 5
\fBungetch\fP
-returns ERR
+returns \fBERR\fP
if there is no more room in the FIFO.
.TP
\fBwgetch\fP
-returns ERR
+returns \fBERR\fP
if the window pointer is null, or
-if its timeout expires without having any data.
+if its timeout expires without having any data, or
+if the execution was interrupted by a signal (\fBerrno\fP will be set to
+\fBEINTR\fP).
.RE
.PP
-Functions with a "mv" prefix first perform a cursor movement using
+Functions with a \*(``mv\*('' prefix first perform a cursor movement using
\fBwmove\fP, and return an error if the position is outside the window,
or if the window pointer is null.
.SH NOTES
discouraged, as it will cause a delay of up to one second while the
keypad code looks for a following function-key sequence.
.PP
-Note that some keys may be the same as commonly used control
-keys, e.g., \fBKEY_ENTER\fP versus control/M, \fBKEY_BACKSPACE\fP versus control/H.
+Some keys may be the same as commonly used control
+keys, e.g.,
+\fBKEY_ENTER\fP versus control/M,
+\fBKEY_BACKSPACE\fP versus control/H.
Some curses implementations may differ according to whether they
treat these control keys specially (and ignore the terminfo), or
use the terminfo definitions.
-\fBNcurses\fR uses the terminfo definition.
+\fBNcurses\fP uses the terminfo definition.
If it says that \fBKEY_ENTER\fP is control/M,
-\fBgetch\fR will return \fBKEY_ENTER\fP
+\fBgetch\fP will return \fBKEY_ENTER\fP
when you press control/M.
.PP
Generally, \fBKEY_ENTER\fP denotes the character(s) sent by the \fIEnter\fP
the standard ASCII characters for carriage-return and line-feed,
.bP
depending on whether \fBnl\fP or \fBnonl\fP was called,
-pressing "Enter" on the regular keyboard may return either a carriage-return
-or line-feed, and finally
+pressing \*(``Enter\*('' on the regular keyboard
+may return either a carriage-return or line-feed, and finally
.bP
-"Enter or send" is the standard description for this key.
+\*(``Enter or send\*('' is the standard description for this key.
.PP
-When using \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR, or
-\fBmvwgetch\fR, nocbreak mode (\fBnocbreak\fR) and echo mode
-(\fBecho\fR) should not be used at the same time.
+When using \fBgetch\fP, \fBwgetch\fP, \fBmvgetch\fP, or
+\fBmvwgetch\fP, nocbreak mode (\fBnocbreak\fP) and echo mode
+(\fBecho\fP) should not be used at the same time.
Depending on the
state of the tty driver when each character is typed, the program may
produce undesirable results.
.PP
-Note that \fBgetch\fR, \fBmvgetch\fR, and \fBmvwgetch\fR may be macros.
+Note that \fBgetch\fP, \fBmvgetch\fP, and \fBmvwgetch\fP may be macros.
.PP
Historically, the set of keypad macros was largely defined by the extremely
function-key-rich keyboard of the AT&T 7300, aka 3B1, aka Safari 4.
Modern
personal computers usually have only a small subset of these.
IBM PC-style
-consoles typically support little more than \fBKEY_UP\fR, \fBKEY_DOWN\fR,
-\fBKEY_LEFT\fR, \fBKEY_RIGHT\fR, \fBKEY_HOME\fR, \fBKEY_END\fR,
-\fBKEY_NPAGE\fR, \fBKEY_PPAGE\fR, and function keys 1 through 12.
+consoles typically support little more than \fBKEY_UP\fP, \fBKEY_DOWN\fP,
+\fBKEY_LEFT\fP, \fBKEY_RIGHT\fP, \fBKEY_HOME\fP, \fBKEY_END\fP,
+\fBKEY_NPAGE\fP, \fBKEY_PPAGE\fP, and function keys 1 through 12.
The Ins key
-is usually mapped to \fBKEY_IC\fR.
+is usually mapped to \fBKEY_IC\fP.
.SH PORTABILITY
The *get* functions are described in the XSI Curses standard, Issue 4.
They
read single-byte characters only.
The standard specifies that they return
-\fBERR\fR on failure, but specifies no error conditions.
+\fBERR\fP on failure, but specifies no error conditions.
.PP
-The echo behavior of these functions on input of \fBKEY_\fR or backspace
+The echo behavior of these functions on input of \fBKEY_\fP or backspace
characters was not specified in the SVr4 documentation.
This description is
adopted from the XSI Curses standard.
.PP
-The behavior of \fBgetch\fR and friends in the presence of handled signals is
+The behavior of \fBgetch\fP and friends in the presence of handled signals is
unspecified in the SVr4 and XSI Curses documentation.
Under historical curses
implementations, it varied depending on whether the operating system's
-implementation of handled signal receipt interrupts a \fBread\fR(2) call in
+implementation of handled signal receipt interrupts a \fBread\fP(2) call in
progress or not, and also (in some implementations) depending on whether an
input timeout or non-blocking mode has been set.
.PP
+\fBKEY_MOUSE\fP is mentioned in XSI Curses, along with a few related
+terminfo capabilities, but no higher-level functions use the feature.
+The implementation in ncurses is an extension.
+.PP
+\fBKEY_RESIZE\fP is an extension first implemented for ncurses.
+NetBSD curses later added this extension.
+.PP
Programmers concerned about portability should be prepared for either of two
-cases: (a) signal receipt does not interrupt \fBgetch\fR; (b) signal receipt
-interrupts \fBgetch\fR and causes it to return ERR with \fBerrno\fR set to
-\fBEINTR\fR.
-Under the \fBncurses\fR implementation, handled signals never
-interrupt \fBgetch\fR.
+cases: (a) signal receipt does not interrupt \fBgetch\fP; (b) signal receipt
+interrupts \fBgetch\fP and causes it to return \fBERR\fP with \fBerrno\fP set to
+\fBEINTR\fP.
.PP
-The \fBhas_key\fR function is unique to \fBncurses\fR.
+The \fBhas_key\fP function is unique to \fBncurses\fP.
We recommend that
-any code using it be conditionalized on the \fBNCURSES_VERSION\fR feature macro.
+any code using it be conditionalized on the \fBNCURSES_VERSION\fP feature macro.
.SH SEE ALSO
-\fBcurses\fR(3X),
-\fBcurs_inopts\fR(3X),
-\fBcurs_outopts\fR(3X),
-\fBcurs_mouse\fR(3X),
-\fBcurs_move\fR(3X),
-\fBcurs_refresh\fR(3X),
-\fBresizeterm\fR(3X).
+\fBcurses\fP(3X),
+\fBcurs_inopts\fP(3X),
+\fBcurs_mouse\fP(3X),
+\fBcurs_move\fP(3X),
+\fBcurs_outopts\fP(3X),
+\fBcurs_refresh\fP(3X),
+\fBcurs_variables\fP(3X),
+\fBresizeterm\fP(3X).
.PP
Comparable functions in the wide-character (ncursesw) library are
described in
-\fBcurs_get_wch\fR(3X).
+\fBcurs_get_wch\fP(3X).
projects / ncurses.git / blobdiff