Provided by: ncurses-doc_6.1+20181013-2ubuntu2_all bug

NAME

       scanw,  wscanw,  mvscanw,  mvwscanw,  vwscanw,  vw_scanw  - convert formatted input from a
       curses window

SYNOPSIS

       #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);

DESCRIPTION

       The scanw, wscanw and mvscanw routines are analogous to scanf [see scanf(3)].  The  effect
       of  these  routines is as though wgetstr were called on the window, and the resulting line
       used as input for sscanf(3).  Fields which do not map to a variable in the fmt  field  are
       lost.

       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>.

RETURN VALUE

       vwscanw  returns  ERR  on  failure and an integer equal to the number of fields scanned on
       success.

       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.

PORTABILITY

       In  this  implementation,  vw_scanw  and  vwscanw  are  equivalent,  to   support   legacy
       applications.  However, the latter (vwscanw) is obsolete:

       ·   The  XSI  Curses standard, Issue 4 described these functions, noting that the function
           vwscanw is marked TO BE WITHDRAWN, and is to be replaced by a function vw_scanw  using
           the <stdarg.h> interface.

       ·   The Single Unix Specification, Version 2 states that vw_scanw  is preferred to vwscanw
           since the latter requires including <varargs.h>, which cannot be used in the same file
           as  <stdarg.h>.   This implementation uses <stdarg.h> for both, because that header is
           included in <curses.h>.

       ·   X/Open Curses, Issue 5 (December 2007) marked vwscanw (along  with  vwprintw  and  the
           termcap interface) as withdrawn.

       Both  XSI  and  The Single Unix Specification, Version 2 state that these functions return
       ERR or OK.

       ·   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.

       ·   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.

       ·   Portable applications should only test if the return value is ERR, since the OK  value
           (zero) is likely to be misleading.

           One possible way to get useful results would be to use a "%n" conversion at the end of
           the format string to ensure that something was processed.

SEE ALSO

       ncurses(3NCURSES), getstr(3NCURSES), printw(3NCURSES), curs_termcap(3X), scanf(3).

                                                                                  scanw(3NCURSES)