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$Id: curs_scanw.3x,v 1.53 2024/04/20 19:18:18 tom Exp $
#include <curses.h>int scanw(const char *fmt, ...); int wscanw(WINDOW *win, const char *fmt, ...); int mvscanw(int y, int x, const char *fmt, ...); int mvwscanw(WINDOW *win, int y, int x, const char *fmt, ...);
int vw_scanw(WINDOW *win, const char *fmt, va_list varglist);
/* obsolete */ int vwscanw(WINDOW *win, const char *fmt, va_list varglist);
\%vwscanw and \%vw_scanw are analogous to \%vscanf(3), and perform a \%wscanw using a variable argument list. The third argument is a \%va_list, a pointer to a list of arguments, as defined in \%stdarg.h.
In \%ncurses , failure occurs if \%vsscanf(3) returns EOF, or if the window pointer win is null.
Functions prefixed with \*(``mv\*('' first perform cursor movement and fail if the position ( y , x ) is outside the window boundaries.
\%ncurses implements \%vsscanf(3) internally if it is unavailable when the library is configured.
\%ncurses defines \%vw_scanw and \%vwscanw identically to support legacy applications. However, the latter is obsolete. .bP X/Open Curses, Issue 4 Version 2 (1996), marked \%vwscanw as requiring \%varargs.h and \*(``TO BE WITHDRAWN\*('', and specified \%vw_scanw using the \%stdarg.h interface. .bP X/Open Curses, Issue 5, Draft 2 (December 2007) marked \%vwscanw (along with \%vwscanw and the termcap interface) as withdrawn. After incorporating review comments, this became X/Open Curses, Issue 7 (2009). .bP \%ncurses provides \%vwscanw, but marks it as deprecated.
X/Open Curses Issues 4 and 7 both state that these functions return ERR or OK. This is likely an erratum. .bP Since the underlying \%scanf(3) returns the number of successful conversions, and SVr4 curses was documented to use this feature, this may have been an editorial solecism introduced by X/Open, rather than an intentional change. .bP This implementation retains compatibility with SVr4 curses . As of 2018, NetBSD curses also returns the number of successful conversions. Both \%ncurses and NetBSD curses call \%vsscanf(3) to scan the string, which returns EOF on error. .bP Portable applications should test only if the return value is ERR, and not compare it to OK, since that value (zero) might be misleading.
One portable way to get useful results would be to use a \*(``%n\*('' conversion at the end of the format string, and check the value of the corresponding variable to determine how many conversions succeeded.libcurses/scanw.c
that early version of curses preceded the ANSI C standard of 1989. The function was unused in Berkeley distributions for over ten years, until 4.4BSD, which employed it in a game. The 4BSD \%scanw did not use \%varargs.h, though that had been available since Seventh Edition Unix (1979). https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/include/\
varargs.h
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 (nor even declare functions) in \%curses.h until 1992.
SVr2 (1984) documented \%scanw and \%wscanw tersely as \*(``scanf through \%stdscr\*('' and \*(``scanf through win\*('', respectively.
SVr3 (1987) added \%mvscanw, and \%mvwscanw, stating
\*(``[t]hese routines correspond to scanf(3S), as do their arguments and return values. \%wgetstr() is called on the window, and the resulting line is used as input for the scan.\*(''
SVr3 also implemented \%vwscanw, describing its third parameter as a \%va_list, defined in \%varargs.h, and referred the reader to the manual pages for \%varargs and \%vprintf for detailed descriptions. (Because the SVr3 documentation does not mention \%vscanf, the reference to \%vprintf might not be an error).
SVr4 (1989) introduced no new variations of \%scanw,
but provided for using either \%varargs.h or \%stdarg.h to
define the \%va_list type.
either header declares "va_list", but only one can be used
X/Open Curses, Issue 4 (1995), defined \%vw_scanw to replace \%vwscanw, stating that its \%va_list type is defined in \%stdarg.h.