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30 .\" $Id: curs_scanw.3x,v 1.51 2024/03/23 20:41:15 tom Exp $
31 .TH curs_scanw 3X 2024-03-23 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
54 read formatted input from a \fIcurses\fR window
57 \fB#include <curses.h>
59 \fBint scanw(const char *\fIfmt\fP, ...);
60 \fBint wscanw(WINDOW *\fIwin\fP, const char *\fIfmt\fP, ...);
61 \fBint mvscanw(int \fIy\fP, int \fIx\fP, const char *\fIfmt\fP, ...);
62 \fBint mvwscanw(WINDOW *\fIwin\fP, int \fIy\fP, int \fIx\fP, const char *\fIfmt\fP, ...);
64 \fBint vw_scanw(WINDOW *\fIwin\fP, const char *\fIfmt\fP, va_list \fIvarglist\fP);
67 \fBint vwscanw(WINDOW *\fIwin\fP, const char *\fIfmt\fP, va_list \fIvarglist\fP);
75 are analogous to \fI\%scanf\fP(3).
77 they call \fB\%wgetstr\fP(3X) with
81 as its first argument,
82 then attempt conversion of the resulting string with \fI\%vsscanf\fP(3).
83 Fields in the string that do not map to a variable in the \fIfmt\fP
84 parameter are discarded.
88 \fB\%vw_scanw\fP are analogous to \fI\%vscanf\fP(3),
89 and perform a \fB\%wscanw\fP using a variable argument list.
90 The third argument is a \fI\%va_list\fP,
91 a pointer to a list of arguments,
92 as defined in \fI\%stdarg.h\fP.
94 These functions return
96 upon failure and otherwise a count of successful conversions;
97 this quantity may be zero.
101 failure occurs if \fI\%vsscanf\fP(3) returns
103 or if the window pointer
107 Functions with a \*(``mv\*('' prefix first perform a cursor movement
109 and fail if the position is outside the window.
111 No wide character counterpart functions are defined by the
114 configuration nor by any standard.
115 They are unnecessary:
116 to retrieve and convert a wide-character string from a
119 use these functions with the \fI\%scanf\fP(3) conversions \*(``%lc\*(''
120 and \*(``%ls\*('' for wide characters and strings,
124 implements \fI\%vsscanf\fP(3) internally if it is unavailable when the
125 library is configured.
127 X/Open Curses, Issue 4, describes these functions.
128 It specifies no error conditions for them.
131 defines \fB\%vw_scanw\fP and \fB\%vwscanw\fP identically to support
134 the latter is obsolete.
136 X/Open Curses, Issue 4, Version 2 (1996),
137 marked \fB\%vwscanw\fP as requiring \fI\%varargs.h\fP and
138 \*(``TO BE WITHDRAWN\*('',
139 and specified \fB\%vw_scanw\fP using the \fI\%stdarg.h\fP interface.
141 X/Open Curses, Issue 5, Draft 2
142 (December 2007) marked \fB\%vwscanw\fP (along with
143 \fB\%vwscanw\fP and the \fItermcap\fP interface) as withdrawn.
144 After incorporating review comments,
146 X/Open Curses, Issue 7 (2009).
149 provides \fB\%vwscanw\fP,
150 but marks it as deprecated.
152 X/Open Curses Issues 4 and 7 both state that these functions return
153 \fBERR\fP or \fBOK\fP.
154 This is likely an erratum.
156 Since the underlying \fI\%scanf\fP(3) returns the number of successful
160 was documented to use this feature,
161 this may have been an editorial solecism introduced by X/Open,
162 rather than an intentional change.
164 This implementation retains compatibility with SVr4
169 also returns the number of successful conversions.
174 call \fI\%vsscanf\fP(3) to scan the string,
175 which returns \fBEOF\fP on error.
177 Portable applications should test only if the return value is \fBERR\fP,
178 and not compare it to \fBOK\fP,
179 since that value (zero) might be misleading.
181 One portable way to get useful results would be to use a \*(``%n\*(''
182 conversion at the end of the format string,
183 and check the value of the corresponding variable to determine how many
184 conversions succeeded.
186 \fB\%scanw\fP was implemented in 4BSD
188 .\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=4BSD/usr/src/lib/\
189 .\" libcurses/scanw.c
190 that early version of
192 preceded the ANSI C standard of 1989.
193 The function was unused in Berkeley distributions for over ten years,
195 which employed it in a game.
196 The 4BSD \fB\%scanw\fP did not use \fI\%varargs.h\fP,
197 though that had been available since Seventh Edition Unix (1979).
198 .\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/include/\
201 (a couple of years after SVr4 was generally available,
202 and after the C standard was published),
203 other developers updated the library,
204 using \fI\%stdarg.h\fP internally in 4.4BSD
206 Even with this improvement,
209 did not use function prototypes
210 (nor even declare functions)
211 in \fI\%curses.h\fP until 1992.
213 SVr2 (1984) documented \fB\%scanw\fP and \fB\%wscanw\fP tersely as
214 \*(``scanf through \fB\%stdscr\fP\*('' and
215 \*(``scanf through \fIwin\fP\*('',
220 \fB\%mvwscanw\fP, stating
223 \*(``[t]hese routines correspond to \fIscanf\fP(3S),
224 as do their arguments and return values.
225 \fB\%wgetstr\fP() is called on the window,
226 and the resulting line is used as input for the scan.\*(''
229 SVr3 also implemented \fB\%vwscanw\fP,
230 describing its third parameter as a \fI\%va_list\fP,
231 defined in \fI\%varargs.h\fP,
232 and referred the reader to the manual pages for \fI\%varargs\fP and
233 \fI\%vprintf\fP for detailed descriptions.
234 (Because the SVr3 documentation does not mention \fI\%vscanf\fP,
235 the reference to \fI\%vprintf\fP might not be an error).
237 SVr4 (1989) introduced no new variations of \fI\%scanw\fP,
238 but provided for using either \fI\%varargs.h\fP or \fI\%stdarg.h\fP to
239 define the \fI\%va_list\fP type.
240 .\" either header declares "va_list", but only one can be used
242 X/Open Curses, Issue 4 (1995),
243 defined \fI\%vw_scanw\fP to replace \fI\%vwscanw\fP,
244 stating that its \fI\%va_list\fP type is defined in \fI\%stdarg.h\fP.
247 \fB\%curs_getstr\fP(3X),
248 \fB\%curs_printw\fP(3X),