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);
The vwscanw and vw_scanw routines are analogous to vscanf(3). They 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>.
Applications may use the return value from the scanw, wscanw, mvscanw and mvwscanw routines to determine the number of fields which were mapped in the call.
Functions with a ``mv'' prefix first perform a cursor movement using wmove, and return an error if the position is outside the window, or if the window pointer is null.
SVr2 documented scanw, wscanw tersely as ``scanf through stdscr'' and tersely as ``scanf through win'', respectively.
SVr3 added mvscanw, and mvwscanw, with a three-line summary saying that they were analogous to scanf(3), explaining that the string which would be output from scanf(3) would instead be output using waddstr on the given window. SVr3 also added vwscanw, saying that the third parameter is a va_list, defined in <varargs.h>, and referring the reader to the manual pages for varargs and vprintf for detailed descriptions. (Because the SVr3 documentation does not mention vscanf, that reference to vprintf may not be an error).
SVr4 added no new variations of scanw, but provided for using <varargs.h> or <stdarg.h> to define the va_list type.
X/Open Curses added vw_scanw to replace vwscanw, stating that its va_list definition requires <stdarg.h>.
Both XSI and The Single Unix Specification, Version 2 state that these
functions return ERR or OK.
.IP • 4
Since the underlying scanf(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.
.IP • 4
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 vsscanf to scan the string,
which returns EOF on error.
.IP • 4
Portable applications should only test if the return value is ERR,
since the OK value (zero) is likely to be misleading.