man/curs_get_wstr.3x

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.\" $Id: curs_get_wstr.3x,v 1.48 2024/04/20 19:18:18 tom Exp $
.TH curs_get_wstr 3X 2024-04-20 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
.ie \n(.g \{\
.ds `` \(lq
.ds '' \(rq
.\}
.el \{\
.ie t .ds `` ``
.el   .ds `` ""
.ie t .ds '' ''
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.\}
.
.de bP
.ie n  .IP \(bu 4
.el    .IP \(bu 2
..
.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 \-
get 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 getn_wstr(wint_t *\fIwstr\fP, int \fIn\fP);
\fBint wget_wstr(WINDOW *\fIwin\fP, wint_t *\fIwstr\fP);
\fBint wgetn_wstr(WINDOW *\fIwin\fP, wint_t *\fIwstr\fP, int \fIn\fP);
.PP
\fBint mvget_wstr(int \fIy\fP, int \fIx\fP, wint_t *\fIwstr\fP);
\fBint mvgetn_wstr(int \fIy\fP, int \fIx\fP, wint_t *\fIwstr\fP, int \fIn\fP);
\fBint mvwget_wstr(WINDOW *\fIwin\fP, int \fIy\fP, int \fIx\fP, wint_t *\fIwstr\fP);
\fBint mvwgetn_wstr(WINDOW *\fIwin\fP, int \fIy\fP, int \fIx\fP, wint_t *\fIwstr\fP, int \fIn\fP);
.fi
.SH DESCRIPTION
The function
\fBwgetn_wstr\fP
is equivalent to a series of calls to
\fBwget_wch\fP(3X)
until a newline or carriage return terminates the series:
.bP
The terminating character is not included in the returned string.
.bP
An end-of-file condition is represented by \fBWEOF\fP,
as defined in \fB<wchar.h>\fP.
.bP
In all instances, the end of the string is terminated
by a null \fBwchar_t\fP.
.bP
The function stores the result in the area pointed to
by the \fIwstr\fP parameter.
.bP
The function reads at most \fIn\fP characters,
thus preventing a possible overflow of the input buffer.
.IP
Any attempt to enter more characters
(other than the terminating newline or carriage return)
causes a beep.
.IP
Function keys also cause a beep and are ignored.
.PP
The user's \fIerase\fP and \fIkill\fP characters are interpreted:
.bP
The \fIerase\fP character (e.g., \fB^H\fP) erases the character
at the end of the buffer, moving the cursor to the left.
.IP
If \fIkeypad\fP mode is on for the window,
\fBKEY_LEFT\fP and \fBKEY_BACKSPACE\fP
are both considered equivalent to the user's \fIerase\fP character.
.bP
The \fIkill\fP character (e.g., \fB^U\fP) erases the entire buffer,
leaving the cursor at the beginning of the buffer.
.PP
Characters input are echoed only if \fBecho\fP is currently on.
In that case,
backspace is echoed as deletion of the previous character
(typically a left motion).
.PP
The
\fBgetn_wstr\fP,
\fBmvgetn_wstr\fP,
\fBmvwgetn_wstr\fP, and
\fBwgetn_wstr\fP
functions are identical
to the
\fBget_wstr\fP,
\fBmvget_wstr\fP,
\fBmvwget_wstr\fP, and
\fBwget_wstr\fP
functions, respectively,
except that the
\fB*n_*\fP
versions read at most
\fIn\fP
characters, letting the application prevent overflow of the
input buffer.
.SH RETURN VALUE
All of these functions return the integer \fBOK\fP upon successful completion.
If unsuccessful, they return \fBERR\fP.
.PP
X/Open defines no error conditions.
.PP
In this implementation,
these functions return an error
.bP
if the window pointer is null,
.bP
if its timeout expires without having any data, or
.bP
if the associated call to
\fBwget_wch\fP
failed.
.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
Any of these functions other than
\fBwgetn_wstr\fP
may be macros.
.PP
Using
\fBget_wstr\fP,
\fBmvget_wstr\fP,
\fBmvwget_wstr\fP, or
\fBwget_wstr\fP
to read a line that
overflows the array pointed to by
\fBwstr\fP
causes undefined
results.
The use of
\fBgetn_wstr\fP,
\fBmvgetn_wstr\fP,
\fBmvwgetn_wstr\fP, or
\fBwgetn_wstr\fP,
respectively, is recommended.
.PP
These functions cannot return \fBKEY_\fP values because there
is no way to distinguish a \fBKEY_\fP value from a valid \fBwchar_t\fP value.
.SH PORTABILITY
These functions are described in The Single Unix Specification, Version 2.
No error conditions are defined.
.PP
This implementation returns \fBERR\fP if the window pointer is null,
or if the lower-level \fBwget_wch\fP call returns an \fBERR\fP.
In the latter case,
an \fBERR\fP return without other data is treated as an end-of-file condition,
and the returned array contains a \fBWEOF\fP followed by a null \fBwchar_t\fP.
.PP
X/Open curses documented these functions to pass an array of \fBwchar_t\fP
in 1997, but that was an error because of this part of the description:
.RS
.PP
The effect of \fBget_wstr\fP is as though a series of calls to
\fBget_wch\fP were made, until a newline character, end-of-line character, or
end-of-file character is processed.
.RE
.PP
The latter function \fIget_wch\fP can return a negative value,
while \fBwchar_t\fP is a unsigned type.
All of the vendors implement this using \fBwint_t\fP, following the standard.
.PP
X/Open Curses, Issue 7 (2009) is unclear regarding whether
the terminating \fInull \fBwchar_t\fR
value is counted in the length parameter \fIn\fP.
X/Open Curses, Issue 7 revised the corresponding description
of \fBwgetnstr\fP to address this issue.
The unrevised description of \fBwget_nwstr\fP can be interpreted either way.
This implementation counts the terminator in the length.
.PP
X/Open Curses does not specify what happens if the length \fIn\fP is negative.
.bP
For analogy with \fBwgetnstr\fP,
\fI\%ncurses\fP 6.2 uses a limit (based on \fBLINE_MAX\fP).
.bP
Some other implementations (such as Solaris xcurses) do the same,
while others (PDCurses) do not allow this.
.bP
NetBSD 7 curses imitates \fI\%ncurses\fP 6.1 in this regard,
treating a \fB\-1\fP as an indefinite number of characters.
.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)