1curs_scanw(3X) curs_scanw(3X)
2
6 scanw, wscanw, mvscanw, mvwscanw, vwscanw, vw_scanw - convert formatted
7 input from a curses window
8
10 #include <curses.h>
11 int scanw(const char *fmt, ...);
13 int wscanw(WINDOW *win, const char *fmt, ...);
14 int mvscanw(int y, int x, const char *fmt, ...);
15 int mvwscanw(WINDOW *win, int y, int x, const char *fmt, ...);
16 int vw_scanw(WINDOW *win, const char *fmt, va_list varglist);
17 /* obsolete */
19 int vwscanw(WINDOW *win, const char *fmt, va_list varglist);
20
22 The scanw, wscanw and mvscanw routines are analogous to scanf [see
23 scanf(3)]. The effect of these routines is as though wgetstr were
24 called on the window, and the resulting line used as input for
25 sscanf(3). Fields which do not map to a variable in the fmt field are
26 lost.
27 The vwscanw and vw_scanw routines are analogous to vscanf(3). They
29 perform a wscanw using a variable argument list. The third argument is
30 a va_list, a pointer to a list of arguments, as defined in <stdarg.h>.
31
33 vwscanw returns ERR on failure and an integer equal to the number of
34 fields scanned on success.
35 Applications may use the return value from the scanw, wscanw, mvscanw
37 and mvwscanw routines to determine the number of fields which were
38 mapped in the call.
39 Functions with a “mv” prefix first perform a cursor movement using
41 wmove, and return an error if the position is outside the window, or if
42 the window pointer is null.
43
45 In this implementation, vw_scanw and vwscanw are equivalent, to support
46 legacy applications. However, the latter (vwscanw) is obsolete:
47 · The XSI Curses standard, Issue 4 described these functions, noting
49 that the function vwscanw is marked TO BE WITHDRAWN, and is to be
50 replaced by a function vw_scanw using the <stdarg.h> interface.
51 · The Single Unix Specification, Version 2 states that vw_scanw is
53 preferred to vwscanw since the latter requires including
54 <varargs.h>, which cannot be used in the same file as <stdarg.h>.
55 This implementation uses <stdarg.h> for both, because that header
56 is included in <curses.h>.
57 · X/Open Curses, Issue 5 (December 2007) marked vwscanw (along with
59 vwprintw and the termcap interface) as withdrawn.
60 Both XSI and The Single Unix Specification, Version 2 state that these
62 functions return ERR or OK.
63 · Since the underlying scanf(3) can return the number of items
65 scanned, and the SVr4 code was documented to use this feature, this
66 is probably an editing error which was introduced in XSI, rather
67 than being done intentionally.
68 · This implementation returns the number of items scanned, for com‐
70 patibility with SVr4 curses. As of 2018, NetBSD curses also
71 returns the number of items scanned. Both ncurses and NetBSD
72 curses call vsscanf to scan the string, which returns EOF on error.
73 · Portable applications should only test if the return value is ERR,
75 since the OK value (zero) is likely to be misleading.
76 One possible way to get useful results would be to use a "%n" con‐
78 version at the end of the format string to ensure that something
79 was processed.
80
82 curses(3X), curs_getstr(3X), curs_printw(3X), curs_termcap(3X),
83 scanf(3).
84 curs_scanw(3X)