170 lines
7.5 KiB
Plaintext
170 lines
7.5 KiB
Plaintext
.\"***************************************************************************
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.\" Copyright 2018-2019,2020 Thomas E. Dickey *
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.\" Copyright 1998-2010,2017 Free Software Foundation, Inc. *
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.\" *
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.\" Permission is hereby granted, free of charge, to any person obtaining a *
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.\" copy of this software and associated documentation files (the *
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.\" "Software"), to deal in the Software without restriction, including *
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.\" without limitation the rights to use, copy, modify, merge, publish, *
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.\" distribute, distribute with modifications, sublicense, and/or sell *
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.\" copies of the Software, and to permit persons to whom the Software is *
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.\" furnished to do so, subject to the following conditions: *
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.\" *
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.\" The above copyright notice and this permission notice shall be included *
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.\" in all copies or substantial portions of the Software. *
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.\" *
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
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.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
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.\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
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.\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
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.\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
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.\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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.\" *
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.\" Except as contained in this notice, the name(s) of the above copyright *
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.\" holders shall not be used in advertising or otherwise to promote the *
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.\" sale, use or other dealings in this Software without prior written *
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.\" authorization. *
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.\"***************************************************************************
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.\"
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.\" $Id: curs_scanw.3x,v 1.28 2020/10/24 09:29:26 tom Exp $
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.TH curs_scanw 3X ""
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.ie \n(.g .ds `` \(lq
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.el .ds `` ``
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.ie \n(.g .ds '' \(rq
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.el .ds '' ''
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.de bP
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.ie n .IP \(bu 4
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.el .IP \(bu 2
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..
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.SH NAME
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\fBscanw\fR,
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\fBwscanw\fR,
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\fBmvscanw\fR,
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\fBmvwscanw\fR,
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\fBvwscanw\fR, \fBvw_scanw\fR \- convert formatted input from a \fBcurses\fR window
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.SH SYNOPSIS
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\fB#include <curses.h>\fR
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.sp
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\fBint scanw(const char *\fP\fIfmt\fP\fB, ...);\fR
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.br
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\fBint wscanw(WINDOW *\fP\fIwin\fP\fB, const char *\fP\fIfmt\fP\fB, ...);\fR
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.br
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\fBint mvscanw(int \fP\fIy\fP\fB, int \fP\fIx\fP\fB, const char *\fP\fIfmt\fP\fB, ...);\fR
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.br
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\fBint mvwscanw(WINDOW *\fP\fIwin\fP\fB, int \fP\fIy\fP\fB, int \fP\fIx\fP\fB, const char *\fP\fIfmt\fP\fB, ...);\fR
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.sp
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\fBint vw_scanw(WINDOW *\fP\fIwin\fP\fB, const char *\fP\fIfmt\fP\fB, va_list \fP\fIvarglist\fP\fB);\fR
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.sp
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/* obsolete */
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.br
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\fBint vwscanw(WINDOW *\fP\fIwin\fP\fB, const char *\fP\fIfmt\fP\fB, va_list \fP\fIvarglist\fP\fB);\fR
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.SH DESCRIPTION
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The \fBscanw\fR, \fBwscanw\fR and \fBmvscanw\fR routines are analogous to
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\fBscanf\fR [see \fBscanf\fR(3)].
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The effect of these routines is as though
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\fBwgetstr\fR were called on the window, and the resulting line used as input
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for \fBsscanf\fR(3).
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Fields which do not map to a variable in the \fIfmt\fR
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field are lost.
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.PP
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The \fBvwscanw\fR and \fBvw_scanw\fR routines are analogous to \fBvscanf\fR(3).
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They perform a \fBwscanw\fR using a variable argument list.
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The third argument is a \fIva_list\fR,
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a pointer to a list of arguments, as defined in \fB<stdarg.h>\fR.
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.SH RETURN VALUE
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\fBvwscanw\fR returns \fBERR\fR on failure and an integer equal to the
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number of fields scanned on success.
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.PP
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Applications may use the return value from the \fBscanw\fR, \fBwscanw\fR,
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\fBmvscanw\fR and \fBmvwscanw\fR routines to determine the number of fields
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which were mapped in the call.
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.PP
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Functions with a \*(``mv\*('' prefix first perform a cursor movement using
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\fBwmove\fP, and return an error if the position is outside the window,
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or if the window pointer is null.
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.SH HISTORY
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While \fBscanw\fP was implemented in 4BSD,
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none of the BSD releases used it until 4.4BSD (in a game).
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That early version of curses was before the ANSI C standard.
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It did not use <varargs.h>, though that was available.
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In 1991 (a couple of years after SVr4 was generally available,
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and after the C standard was published),
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other developers updated the library,
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using <stdarg.h> internally in 4.4BSD curses.
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Even with this improvement,
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BSD curses did not use function prototypes (or even declare
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functions) in the <curses.h> header until 1992.
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.PP
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SVr2 documented
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\fBscanw\fP,
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\fBwscanw\fP
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tersely as \*(``scanf through \fIstdscr\fP\*('' and
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tersely as \*(``scanf through \fIwin\fP\*('', respectively.
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.PP
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SVr3 added
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\fBmvscanw\fP, and
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\fBmvwscanw\fP, with a three-line summary saying that they were analogous
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to \fBscanf\fP(3),
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explaining that the string which would be output from \fBscanf\fP(3) would
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instead be output using \fBwaddstr\fP on the given window.
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SVr3 also added \fBvwscanw\fP, saying that the third parameter
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is a \fBva_list\fP, defined in <varargs.h>,
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and referring the reader to the manual pages for \fIvarargs\fP and
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\fIvprintf\fP for detailed descriptions.
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(Because the SVr3 documentation does not mention \fIvscanf\fP,
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that reference to \fIvprintf\fP may not be an error).
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.PP
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SVr4 added no new variations of \fBscanw\fP,
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but provided for using <varargs.h> or <stdarg.h> to define the \fBva_list\fP
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type.
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.PP
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X/Open Curses added \fBvw_scanw\fP to replace \fBvwscanw\fP,
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stating that its \fBva_list\fP definition requires <stdarg.h>.
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.SH PORTABILITY
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In this implementation, \fBvw_scanw\fP and \fBvwscanw\fP are equivalent,
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to support legacy applications.
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However, the latter (\fBvwscanw\fP) is obsolete:
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.bP
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The XSI Curses standard, Issue 4 described these functions,
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noting that the function
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\fBvwscanw\fR is marked TO BE WITHDRAWN, and is to be replaced by a function
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\fBvw_scanw\fR using the \fB<stdarg.h>\fR interface.
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.bP
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The Single Unix Specification, Version 2 states that
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\fBvw_scanw\fR is preferred to \fBvwscanw\fR since the latter requires
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including \fB<varargs.h>\fR, which
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cannot be used in the same file as \fB<stdarg.h>\fR.
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This implementation uses \fB<stdarg.h>\fR for both, because that header
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is included in \fB<curses.h\fR>.
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.bP
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X/Open Curses, Issue 5 (December 2007) marked \fBvwscanw\fP (along with
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\fBvwprintw\fP and the termcap interface) as withdrawn.
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.LP
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Both XSI and The Single Unix Specification, Version 2 state that these
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functions return \fBERR\fP or \fBOK\fP.
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.bP
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Since the underlying \fBscanf\fR(3) can return the number of items scanned,
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and the SVr4 code was documented to use this feature,
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this is probably an editing error which was introduced in XSI,
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rather than being done intentionally.
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.bP
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This implementation returns the number of items scanned,
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for compatibility with SVr4 curses.
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As of 2018, NetBSD curses also returns the number of items scanned.
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Both ncurses and NetBSD curses call \fBvsscanf\fP to scan the string,
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which returns \fBEOF\fP on error.
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.bP
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Portable applications should only test if the return value is \fBERR\fP,
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since the \fBOK\fP value (zero) is likely to be misleading.
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.IP
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One possible way to get useful results would be to use a "%n" conversion
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at the end of the format string to ensure that something was processed.
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.SH SEE ALSO
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.na
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\fBcurses\fR(3X),
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\fBcurs_getstr\fR(3X),
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\fBcurs_printw\fR(3X),
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\fBcurs_termcap\fP(3X),
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\fBscanf\fR(3).
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