.\"***************************************************************************
-.\" Copyright (c) 1998-2010,2017 Free Software Foundation, Inc. *
+.\" Copyright 2018-2019,2020 Thomas E. Dickey *
+.\" Copyright 1998-2010,2017 Free Software Foundation, Inc. *
.\" *
.\" Permission is hereby granted, free of charge, to any person obtaining a *
.\" copy of this software and associated documentation files (the *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: curs_scanw.3x,v 1.19 2017/11/21 00:46:31 tom Exp $
+.\" $Id: curs_scanw.3x,v 1.28 2020/10/24 09:29:26 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,
.SH SYNOPSIS
\fB#include <curses.h>\fR
.sp
-\fBint scanw(char *fmt, ...);\fR
+\fBint scanw(const char *\fP\fIfmt\fP\fB, ...);\fR
.br
-\fBint wscanw(WINDOW *win, char *fmt, ...);\fR
+\fBint wscanw(WINDOW *\fP\fIwin\fP\fB, const char *\fP\fIfmt\fP\fB, ...);\fR
.br
-\fBint mvscanw(int y, int x, char *fmt, ...);\fR
+\fBint mvscanw(int \fP\fIy\fP\fB, int \fP\fIx\fP\fB, const char *\fP\fIfmt\fP\fB, ...);\fR
.br
-\fBint mvwscanw(WINDOW *win, int y, int x, char *fmt, ...);\fR
-.br
-\fBint vw_scanw(WINDOW *win, char *fmt, va_list varglist);\fR
+\fBint mvwscanw(WINDOW *\fP\fIwin\fP\fB, int \fP\fIy\fP\fB, int \fP\fIx\fP\fB, const char *\fP\fIfmt\fP\fB, ...);\fR
+.sp
+\fBint vw_scanw(WINDOW *\fP\fIwin\fP\fB, const char *\fP\fIfmt\fP\fB, va_list \fP\fIvarglist\fP\fB);\fR
+.sp
+/* obsolete */
.br
-\fBint vwscanw(WINDOW *win, char *fmt, va_list varglist);\fR
+\fBint vwscanw(WINDOW *\fP\fIwin\fP\fB, const char *\fP\fIfmt\fP\fB, va_list \fP\fIvarglist\fP\fB);\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
+\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
+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).
\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
+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 HISTORY
+While \fBscanw\fP was implemented in 4BSD,
+none of the BSD releases used it until 4.4BSD (in a game).
+That early version of curses was before the ANSI C standard.
+It did not use <varargs.h>, though that was available.
+In 1991 (a couple of years after SVr4 was generally available,
+and after the C standard was published),
+other developers updated the library,
+using <stdarg.h> internally in 4.4BSD curses.
+Even with this improvement,
+BSD curses did not use function prototypes (or even declare
+functions) in the <curses.h> header until 1992.
+.PP
+SVr2 documented
+\fBscanw\fP,
+\fBwscanw\fP
+tersely as \*(``scanf through \fIstdscr\fP\*('' and
+tersely as \*(``scanf through \fIwin\fP\*('', respectively.
+.PP
+SVr3 added
+\fBmvscanw\fP, and
+\fBmvwscanw\fP, with a three-line summary saying that they were analogous
+to \fBscanf\fP(3),
+explaining that the string which would be output from \fBscanf\fP(3) would
+instead be output using \fBwaddstr\fP on the given window.
+SVr3 also added \fBvwscanw\fP, saying that the third parameter
+is a \fBva_list\fP, defined in <varargs.h>,
+and referring the reader to the manual pages for \fIvarargs\fP and
+\fIvprintf\fP for detailed descriptions.
+(Because the SVr3 documentation does not mention \fIvscanf\fP,
+that reference to \fIvprintf\fP may not be an error).
+.PP
+SVr4 added no new variations of \fBscanw\fP,
+but provided for using <varargs.h> or <stdarg.h> to define the \fBva_list\fP
+type.
+.PP
+X/Open Curses added \fBvw_scanw\fP to replace \fBvwscanw\fP,
+stating that its \fBva_list\fP definition requires <stdarg.h>.
.SH PORTABILITY
-The XSI Curses standard, Issue 4 describes these functions. The function
+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
-\fBcurses\fR(3X), \fBcurs_getstr\fR(3X), \fBcurs_printw\fR(3X), \fBscanf\fR(3)
+.na
+\fBcurses\fR(3X),
+\fBcurs_getstr\fR(3X),
+\fBcurs_printw\fR(3X),
+\fBcurs_termcap\fP(3X),
+\fBscanf\fR(3).
projects / ncurses.git / blobdiff