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30 .\" $Id: curs_scanw.3x,v 1.53 2024/04/20 19:18:18 tom Exp $
31 .TH curs_scanw 3X 2024-04-20 "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 prefixed with \*(``mv\*('' first perform cursor movement and
111 is outside the window boundaries.
113 No wide character counterpart functions are defined by the
116 configuration nor by any standard.
117 They are unnecessary:
118 to retrieve and convert a wide-character string from a
121 use these functions with the \fI\%scanf\fP(3) conversions \*(``%lc\*(''
122 and \*(``%ls\*('' for wide characters and strings,
126 implements \fI\%vsscanf\fP(3) internally if it is unavailable when the
127 library is configured.
130 Issue 4 describes these functions.
131 It specifies no error conditions for them.
134 defines \fB\%vw_scanw\fP and \fB\%vwscanw\fP identically to support
137 the latter is obsolete.
140 Issue 4 Version 2 (1996),
141 marked \fB\%vwscanw\fP as requiring \fI\%varargs.h\fP and
142 \*(``TO BE WITHDRAWN\*('',
143 and specified \fB\%vw_scanw\fP using the \fI\%stdarg.h\fP interface.
147 Draft 2 (December 2007) marked \fB\%vwscanw\fP (along with
148 \fB\%vwscanw\fP and the \fItermcap\fP interface) as withdrawn.
149 After incorporating review comments,
151 X/Open Curses, Issue 7 (2009).
154 provides \fB\%vwscanw\fP,
155 but marks it as deprecated.
157 X/Open Curses Issues 4 and 7 both state that these functions return
158 \fBERR\fP or \fBOK\fP.
159 This is likely an erratum.
161 Since the underlying \fI\%scanf\fP(3) returns the number of successful
165 was documented to use this feature,
166 this may have been an editorial solecism introduced by X/Open,
167 rather than an intentional change.
169 This implementation retains compatibility with SVr4
174 also returns the number of successful conversions.
179 call \fI\%vsscanf\fP(3) to scan the string,
180 which returns \fBEOF\fP on error.
182 Portable applications should test only if the return value is \fBERR\fP,
183 and not compare it to \fBOK\fP,
184 since that value (zero) might be misleading.
186 One portable way to get useful results would be to use a \*(``%n\*(''
187 conversion at the end of the format string,
188 and check the value of the corresponding variable to determine how many
189 conversions succeeded.
191 \fB\%scanw\fP was implemented in 4BSD
193 .\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=4BSD/usr/src/lib/\
194 .\" libcurses/scanw.c
195 that early version of
197 preceded the ANSI C standard of 1989.
198 The function was unused in Berkeley distributions for over ten years,
200 which employed it in a game.
201 The 4BSD \fB\%scanw\fP did not use \fI\%varargs.h\fP,
202 though that had been available since Seventh Edition Unix (1979).
203 .\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/include/\
206 (a couple of years after SVr4 was generally available,
207 and after the C standard was published),
208 other developers updated the library,
209 using \fI\%stdarg.h\fP internally in 4.4BSD
211 Even with this improvement,
214 did not use function prototypes
215 (nor even declare functions)
216 in \fI\%curses.h\fP until 1992.
218 SVr2 (1984) documented \fB\%scanw\fP and \fB\%wscanw\fP tersely as
219 \*(``scanf through \fB\%stdscr\fP\*('' and
220 \*(``scanf through \fIwin\fP\*('',
225 \fB\%mvwscanw\fP, stating
228 \*(``[t]hese routines correspond to \fIscanf\fP(3S),
229 as do their arguments and return values.
230 \fB\%wgetstr\fP() is called on the window,
231 and the resulting line is used as input for the scan.\*(''
234 SVr3 also implemented \fB\%vwscanw\fP,
235 describing its third parameter as a \fI\%va_list\fP,
236 defined in \fI\%varargs.h\fP,
237 and referred the reader to the manual pages for \fI\%varargs\fP and
238 \fI\%vprintf\fP for detailed descriptions.
239 (Because the SVr3 documentation does not mention \fI\%vscanf\fP,
240 the reference to \fI\%vprintf\fP might not be an error).
242 SVr4 (1989) introduced no new variations of \fI\%scanw\fP,
243 but provided for using either \fI\%varargs.h\fP or \fI\%stdarg.h\fP to
244 define the \fI\%va_list\fP type.
245 .\" either header declares "va_list", but only one can be used
247 X/Open Curses, Issue 4 (1995),
248 defined \fI\%vw_scanw\fP to replace \fI\%vwscanw\fP,
249 stating that its \fI\%va_list\fP type is defined in \fI\%stdarg.h\fP.
252 \fB\%curs_getstr\fP(3X),
253 \fB\%curs_printw\fP(3X),