path: root/man/curs_get_wstr.3x

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.\" $Id: curs_get_wstr.3x,v 1.79 2025/10/21 00:08:50 tom Exp $
.TH curs_get_wstr 3X 2025-10-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
.ie \n(.g \{\
.ds `` \(lq
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.el \{\
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.de bP
.ie n  .IP \(bu 4
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..
.SH NAME
\fB\%get_wstr\fP,
\fB\%getn_wstr\fP,
\fB\%wget_wstr\fP,
\fB\%wgetn_wstr\fP,
\fB\%mvget_wstr\fP,
\fB\%mvgetn_wstr\fP,
\fB\%mvwget_wstr\fP,
\fB\%mvwgetn_wstr\fP \-
read a wide-character string from a \fIcurses\fR terminal keyboard
.SH SYNOPSIS
.nf
\fB#include <curses.h>
.PP
\fBint get_wstr(wint_t * \fIwstr\fP);
\fBint wget_wstr(WINDOW * \fIwin\fP, wint_t * \fIwstr\fP);
\fBint mvget_wstr(int \fIy\fP, int \fIx\fP, wint_t * \fIwstr\fP);
\fBint mvwget_wstr(WINDOW * \fIwin\fP, int \fIy\fP, int \fIx\fP, wint_t * \fIwstr\fP);
.PP
\fBint getn_wstr(wint_t * \fIwstr\fP, int \fIn\fP);
\fBint wgetn_wstr(WINDOW * \fIwin\fP, wint_t * \fIwstr\fP, int \fIn\fP);
\fBint mvgetn_wstr(int \fIy\fP, int \fIx\fP, wint_t * \fIwstr\fP, int \fIn\fP);
\fBint mvwgetn_wstr(WINDOW * \fIwin\fP, int \fIy\fP, int \fIx\fP, wint_t * \fIwstr\fP, int \fIn\fP);
.fi
.SH DESCRIPTION
.B \%wget_wstr
populates a user-supplied wide-character string buffer
.I wstr
by repeatedly calling \fBwget_wch\fP(3X)
with the
.I win
argument
until a line feed or carriage return character is input.
The function
.bP
does not copy the terminating character to
.IR wstr ";"
.bP
populates
.I wstr
with
.I WEOF
(as defined in
.IR \%wchar.h )
if an end-of-file condition occurs on the input;
.bP
always terminates the string with a null wide character
(after any
.IR WEOF );
.bP
interprets the screen's wide erase and wide kill characters
(see \fB\%erasewchar\fP(3X) and \fB\%killwchar\fP(3X));
.bP
recognizes function keys only if the screen's keypad option is enabled
(see \fB\%keypad\fP(3X));
.bP
treats the function keys
.B \%KEY_LEFT
and
.B \%KEY_BACKSPACE
the same as the wide erase character;
and
.bP
discards function key inputs other than those
treated as the wide erase or wide kill characters,
calling \fBbeep\fP(3X).
.PP
The wide erase character replaces the character at the end of the buffer
with a null wide character,
while the wide kill character does the same for the entire buffer.
.PP
If the screen's echo option is enabled
(see \fBecho\fP(3X)),
.B \%wget_wstr
updates
.I win
with \fB\%wadd_wch\fP(3X).
Further,
.bP
the wide erase character
and its function key synonyms
move the cursor to the left,
and
.bP
the wide kill character returns the cursor to where it was located when
.B \%wget_wstr
was called.
.PP
.B \%wgetn_wstr
is similar,
but reads at most
.I n
wide characters,
aiding the application to avoid overrunning the buffer to which
.I wstr
points.
.I curses
ignores an attempt to input more than
.I n
wide characters
(other than the terminating line feed or carriage return),
calling \fBbeep\fP(3X).
If
.I n
is negative,
.B \%wgetn_wstr
reads up to
.I LINE_MAX
wide characters
(see
.IR sysconf (3)).
.PP
\fB\%ncurses\fP(3X) describes the variants of these functions.
.SH RETURN VALUE
These functions return
.B OK
on success and
.B ERR
on failure.
.PP
In
.IR \%ncurses ","
these functions fail if
.bP
the
.I curses
screen has not been initialized,
.bP
(for functions taking a
.I \%WINDOW
pointer argument)
.I win
is a null pointer,
.bP
.I wstr
is a null pointer,
or
.bP
an internal \fB\%wget_wch\fP(3X) call fails.
.PP
Functions prefixed with \*(``mv\*('' first perform cursor movement and
fail if the position
.RI ( y ,
.IR x )
is outside the window boundaries.
.SH NOTES
All of these functions except
.B \%wgetn_wstr
may be implemented as macros.
.PP
Reading input that overruns the buffer pointed to by
.I wstr
causes undefined results.
Use the
.BR n -infixed
functions,
and allocate sufficient storage for
.I wstr
\(em at least
.IR n +1
times
.BR sizeof(wchar_t) "."
.PP
These functions cannot store a
.B KEY_
value in
.I wstr
because there is no way to distinguish it
from a valid
.I \%wchar_t
value.
.PP
While these functions conceptually implement
a series of calls to
.BR \%wget_wch ","
they also temporarily change properties of the
.I curses
screen to permit simple editing of the input buffer.
Each function saves the screen's state,
calls \fBnl\fP(3X),
and,
if the screen was in canonical (\*(``cooked\*('') mode,
\fB\%cbreak\fP(3X).
Before returning,
it restores the saved screen state.
Other implementations differ in detail,
affecting which control characters they can accept in the buffer;
see section \*(``PORTABILITY\*('' below.
.PP
Unlike \fBgetstr\fP(3X) and related functions of
.IR \%ncurses 's
non-wide API,
these functions do not return
.B \%KEY_RESIZE
if a
.I \%SIGWINCH
event interrupts the function.
.SH EXTENSIONS
.BR \%getn_wstr ","
.BR \%wgetn_wstr ","
.BR \%mvgetn_wstr ","
and
.BR \%mvwgetn_wstr "'s"
handing of negative
.I n
values is an
.I \%ncurses
extension.
.SH PORTABILITY
Applications employing
.I \%ncurses
extensions should condition their use on the visibility of the
.B \%NCURSES_VERSION
preprocessor macro.
.PP
X/Open Curses Issue\ 4 describes these functions.
It specifies no error conditions for them.
.PP
Issue\ 4 documented these functions as passing an array of
.IR wchar_t ","
but that was an error,
conflicting with the following language in the standard.
.RS
.PP
The effect of
.IR \%get_wstr "()"
is as though a series of calls to
.IR \%get_wch "()"
were made,
until a newline character,
end-of-line character,
or end-of-file character is processed.
.\" X/Open Curses Issue 4, Version 2, p. 96.
.RE
.PP
.I \%get_wch
can return a negative value
.RI ( WEOF ),
but
.I \%wchar_t
is a unsigned type.
All of the vendors implement these functions using
.IR \%wint_t ","
following the Issue\ 7 standard.
.PP
X/Open Curses Issue\ 7 is unclear whether the terminating null wide character
counts toward the length parameter
.IR n "."
A similar issue affected
.I \%wgetnstr
in Issue\ 4,
Version\ 2;
Issue\ 7 revised that function's description to address the issue,
but not that of
.IR \%wget_nwstr ","
leaving it ambiguous.
.I \%ncurses
counts the terminator in the length.
.PP
X/Open Curses does not specify what happens if the length
.I n
is negative.
.bP
For consistency with
.IR \%wgetnstr ","
.I \%ncurses
6.2 uses a limit based on
.IR LINE_MAX "."
.bP
Some other implementations
(such as Solaris
.IR xcurses )
do the same,
while others
.RI \%( PDCurses )
do not permit a negative
.IR n "."
.bP
NetBSD\ 7
.I curses
imitates
.I \%ncurses
6.1 and earlier,
treating a negative
.I n
as an unbounded count of wide characters.
.PP
Implementations vary in their handling of input control characters.
.bP
While they may enable the screen's echo option,
some do not take it out of raw mode,
and may take cbreak mode into account
when deciding whether to handle echoing within
.I \%wgetn_wstr
or to rely on it as a side effect of calling
.IR \%wget_wch "."
.IP
Since 1995,
.I \%ncurses
has provided handlers for
.I SIGINTR
and
.I SIGQUIT
events,
which are typically generated at the keyboard with
.B \*^C
and
.B \*^\e
respectively.
In cbreak mode,
those handlers catch a signal and stop the program,
whereas other implementations write those characters into the buffer.
.bP
Starting with
.I \%ncurses
6.3 (2021),
.I \%wgetn_wstr
preserves raw mode if the screen was already in that state,
allowing one to enter the characters the terminal interprets
as interrupt and quit events
into the buffer,
for consistency with SVr4
.IR curses 's
.IR \%wgetnstr .
.SH HISTORY
X/Open Curses Issue\ 4 (1995) initially specified these functions.
The System\ V Interface Definition Version\ 4
of the same year
specified functions named
.I \%wgetwstr
and
.I \%wgetnwstr
(and the usual variants).
.\" SVID 4, vol 3., p. 500
These were later additions to
.RI SVr4. x ,
not appearing in the first SVr4 (1989).
Except in name,
their declarations did not differ from X/Open's later
.I \%wget_wstr
and
.I \%wgetn_wstr
until
X/Open Curses Issue 7 (2009)
eventually changed the type of the buffer argument to a pointer to
.IR \%wint_t "."
.SH SEE ALSO
\fB\%curs_getstr\fP(3X) describes comparable functions of the
.I \%ncurses
library in its non-wide-character configuration.
.PP
\fB\%curses\fP(3X),
\fB\%curs_get_wch\fP(3X)