- The XSI Curses standard, Issue 4 describes these functions. The func-
- tion vwscanw is marked TO BE WITHDRAWN, and is to be replaced by a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>.
+ In this implementation, vw_scanw and vwscanw are equivalent, to support
+ legacy applications. However, the latter (vwscanw) is obsolete:
+
+ o 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+ that the function vwscanw is marked TO BE WITHDRAWN, and is to be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.
+
+ o 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>.
+
+ o 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+ vwprintw and the termcap interface) as withdrawn.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. 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.
+ functions return ERR or OK.
+
+ o 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.
+
+ o This implementation returns the number of items scanned, for com-
+ patibility 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.
+
+ o 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" con-
+ version at the end of the format string to ensure that something
+ was processed.