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.\"***************************************************************************
.\" Copyright (c) 1998-2018,2019 Free Software Foundation, Inc.              *
.\"                                                                          *
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.\" furnished to do so, subject to the following conditions:                 *
.\"                                                                          *
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.\" in all copies or substantial portions of the Software.                   *
.\"                                                                          *
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.\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
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.\"***************************************************************************
.\"
.\" $Id: curs_scanw.3x,v 1.25 2019/11/30 21:06:30 tom Exp $
.TH curs_scanw 3X ""
.ie \n(.g .ds `` \(lq
.el       .ds `` ``
.ie \n(.g .ds '' \(rq
.el       .ds '' ''
.de bP
.ie n  .IP \(bu 4
.el    .IP \(bu 2
..
.SH NAME
\fBscanw\fR,
\fBwscanw\fR,
\fBmvscanw\fR,
\fBmvwscanw\fR,
\fBvwscanw\fR, \fBvw_scanw\fR \- convert formatted input from a \fBcurses\fR window
.SH SYNOPSIS
\fB#include <curses.h>\fR
.sp
\fBint scanw(const char *fmt, ...);\fR
.br
\fBint wscanw(WINDOW *win, const char *fmt, ...);\fR
.br
\fBint mvscanw(int y, int x, const char *fmt, ...);\fR
.br
\fBint mvwscanw(WINDOW *win, int y, int x, const char *fmt, ...);\fR
.br
\fBint vw_scanw(WINDOW *win, const char *fmt, va_list varglist);\fR
.sp
/* obsolete */
.br
\fBint vwscanw(WINDOW *win, const char *fmt, va_list varglist);\fR
.SH DESCRIPTION
The \fBscanw\fR, \fBwscanw\fR and \fBmvscanw\fR routines are analogous to
\fBscanf\fR [see \fBscanf\fR(3)].
The effect of these routines is as though
\fBwgetstr\fR were called on the window, and the resulting line used as input
for \fBsscanf\fR(3).
Fields which do not map to a variable in the \fIfmt\fR
field are lost.
.PP
The \fBvwscanw\fR and \fBvw_scanw\fR routines are analogous to \fBvscanf\fR(3).
They perform a \fBwscanw\fR using a variable argument list.
The third argument is a \fIva_list\fR,
a pointer to a list of arguments, as defined in \fB<stdarg.h>\fR.
.SH RETURN VALUE
\fBvwscanw\fR returns \fBERR\fR on failure and an integer equal to the
number of fields scanned on success.
.PP
Applications may use the return value from the \fBscanw\fR, \fBwscanw\fR,
\fBmvscanw\fR and \fBmvwscanw\fR routines to determine the number of fields
which were mapped in the call.
.PP
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 PORTABILITY
In this implementation, \fBvw_scanw\fP and \fBvwscanw\fP are equivalent,
to support legacy applications.
However, the latter (\fBvwscanw\fP) is obsolete:
.bP
The XSI Curses standard, Issue 4 described these functions,
noting that the function
\fBvwscanw\fR is marked TO BE WITHDRAWN, and is to be replaced by a function
\fBvw_scanw\fR using the \fB<stdarg.h>\fR interface.
.bP
The Single Unix Specification, Version 2 states that
\fBvw_scanw\fR  is preferred to \fBvwscanw\fR since the latter requires
including \fB<varargs.h>\fR, which
cannot be used in the same file as \fB<stdarg.h>\fR.
This implementation uses \fB<stdarg.h>\fR for both, because that header
is included in \fB<curses.h\fR>.
.bP
X/Open Curses, Issue 5 (December 2007) marked \fBvwscanw\fP (along with
\fBvwprintw\fP and the termcap interface) as withdrawn.
.LP
Both XSI and The Single Unix Specification, Version 2 state that these
functions return \fBERR\fP or \fBOK\fP.
.bP
Since the underlying \fBscanf\fR(3) can return the number of items scanned,
and the SVr4 code was documented to use this feature,
this is probably an editing error which was introduced in XSI,
rather than being done intentionally.
.bP
This implementation returns the number of items scanned,
for compatibility with SVr4 curses.
As of 2018, NetBSD curses also returns the number of items scanned.
Both ncurses and NetBSD curses call \fBvsscanf\fP to scan the string,
which returns \fBEOF\fP on error.
.bP
Portable applications should only test if the return value is \fBERR\fP,
since the \fBOK\fP value (zero) is likely to be misleading.
.IP
One possible way to get useful results would be to use a "%n" conversion
at the end of the format string to ensure that something was processed.
.SH SEE ALSO
.na
\fBcurses\fR(3X),
\fBcurs_getstr\fR(3X),
\fBcurs_printw\fR(3X),
\fBcurs_termcap\fP(3X),
\fBscanf\fR(3).