ncurses/man/curs_instr.3x

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.\" $Id: curs_instr.3x,v 1.82 2025/10/21 00:04:35 tom Exp $
.TH curs_instr 3X 2025-10-20 "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 '' ""
.\}
.
.de bP
.ie n  .IP \(bu 4
.el    .IP \(bu 2
..
.SH NAME
\fB\%instr\fP,
\fB\%winstr\fP,
\fB\%mvinstr\fP,
\fB\%mvwinstr\fP,
\fB\%innstr\fP,
\fB\%winnstr\fP,
\fB\%mvinnstr\fP,
\fB\%mvwinnstr\fP \-
get a string from a \fIcurses\fR window
.SH SYNOPSIS
.nf
\fB#include <curses.h>
.PP
\fBint instr(char * \fIstr\fP);
\fBint winstr(WINDOW * \fIwin\fP, char * \fIstr\fP);
\fBint mvinstr(int \fIy\fP, int \fIx\fP, char * \fIstr\fP);
\fBint mvwinstr(WINDOW * \fIwin\fP, int \fIy\fP, int \fIx\fP, char * \fIstr\fP);
.PP
\fBint innstr(char * \fIstr\fP, int \fIn\fP);
\fBint winnstr(WINDOW * \fIwin\fP, char * \fIstr\fP, int \fIn\fP);
\fBint mvinnstr(int \fIy\fP, int \fIx\fP, char * \fIstr\fP, int \fIn\fP);
\fBint mvwinnstr(WINDOW * \fIwin\fP, int \fIy\fP, int \fIx\fP, char * \fIstr\fP, int \fIn\fP);
.fi
.SH DESCRIPTION
.B \%winstr
extracts a string from a
.I curses
window
.IR win ","
starting at the cursor and stopping at the end of the line,
and stores it in
.IR str ","
terminating it with a null character
and
omitting any attributes and color pair identifier
that
.I curses
associates with each character.
.B \%winnstr
does the same,
but copies at most
.I n
characters from
.IR win "."
A negative
.I n
implies no limit;
.B \%winnstr
then works like
.BR \%winstr "."
\fB\%ncurses\fP(3X) describes the variants of these functions.
.SH RETURN VALUE
These functions return the count of characters copied from
.I win
to
.I str
(not including the null terminator),
or
.B ERR
upon 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,
or
.bP
.I str
is a null pointer.
.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 \%winnstr
may be implemented as macros.
.PP
Reading a line that overflows the array pointed to by
.I str
with
and its variants causes undefined results.
Instead,
use the
.IR n -infixed
functions with a positive
.I n
argument no larger than the size of the buffer backing
.IR str "."
.SH EXTENSIONS
.BR \%innstr ","
.BR \%winnstr ","
.BR \%mvinnstr ","
and
.BR \%mvwinnstr "'s"
acceptance 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
X/Open Curses Issues 4 and 7 both state that
.IR \%instr ","
.IR \%winstr ","
.IR \%mvinstr ","
and
.I \%mvwinstr
return
.I OK
rather than a character count.
.\" X/Open Issue 4, Version 2, p. 117, PDF p. 137
.\" Issue 7 makes the same claim.
This is likely an erratum.
.bP
SVr3.1 and SVr4 implemented
.I \%winstr
as a wrapper around
.IR \%winnstr ","
returning the latter's return value.
X/Open Curses's specification thus may have been an editorial solecism
copied from System\ V's documentation
(see below)
by X/Open,
rather than an intentional change.
.bP
.I \%ncurses
retains compatibility with System\ V
.I curses
behavior.
.PP
SVr4 describes a successful return value only as
\*(``an integer value other than
.IR ERR \*(''. \" Courier roman in source; SVID 4, vol. 3, p. 503
.PP
SVr4 does not
document whether
.I n
counts the null terminator that these functions write to
.IR str "."
.SH HISTORY
SVr3.1 (1987)
introduced these functions.
.SH SEE ALSO
\fB\%curs_inwstr\fP(3X) describes comparable functions of the
.I \%ncurses
library in its wide-character configuration
.RI \%( ncursesw ).
.PP
\fB\%curses\fP(3X),
\fB\%curs_inch\fP(3X),
\fB\%curs_inchstr\fP(3X)