Provided by: ncurses-doc_6.1-1ubuntu1_all bug


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


       #include <curses.h>

       int scanw(char *fmt, ...);
       int wscanw(WINDOW *win, char *fmt, ...);
       int mvscanw(int y, int x, char *fmt, ...);
       int mvwscanw(WINDOW *win, int y, int x, char *fmt, ...);
       int vw_scanw(WINDOW *win, char *fmt, va_list varglist);
       int vwscanw(WINDOW *win, char *fmt, va_list varglist);


       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

       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>.


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

       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.


       The XSI Curses standard, Issue 4 describes  these  functions.   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       marked  TO BE WITHDRAWN, and is to be replaced by a function vw_scanw using the 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>.

       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.   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.


       ncurses(3NCURSES), getstr(3NCURSES), printw(3NCURSES), scanf(3)