- The XSI Curses standard, Issue 4 describes these func-
- tions. The function <STRONG>vwscanw</STRONG> is marked TO BE WITHDRAWN,
- and is to be replaced by a function <STRONG>vw_scanw</STRONG> using the
- <STRONG><stdarg.h></STRONG> interface. The Single Unix Specification, Ver-
- sion 2 states that <STRONG>vw_scanw</STRONG> is preferred to <STRONG>vwscanw</STRONG> since
- the latter requires including <STRONG><varargs.h></STRONG>, which cannot be
- used in the same file as <STRONG><stdarg.h></STRONG>. This implementation
- uses <STRONG><stdarg.h></STRONG> for both, because that header is included
- in <STRONG><curses.h</STRONG>>.
-
- Both XSI and The Single Unix Specification, Version 2
- state that these functions return ERR or OK. Since the
- underlying <STRONG>scanf</STRONG> 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 applica-
- tions should only test if the return value is ERR, since
- the OK value (zero) is likely to be misleading. One pos-
- sible 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.
+ In this implementation, <STRONG>vw_scanw</STRONG> and <STRONG>vwscanw</STRONG> are equivalent, to support
+ legacy applications. However, the latter (<STRONG>vwscanw</STRONG>) is obsolete:
+
+ <STRONG>o</STRONG> The XSI Curses standard, Issue 4 described these functions, noting
+ that the function <STRONG>vwscanw</STRONG> is marked TO BE WITHDRAWN, and is to be
+ replaced by a function <STRONG>vw_scanw</STRONG> using the <STRONG><stdarg.h></STRONG> interface.
+
+ <STRONG>o</STRONG> The Single Unix Specification, Version 2 states that <STRONG>vw_scanw</STRONG> is
+ preferred to <STRONG>vwscanw</STRONG> since the latter requires including
+ <STRONG><varargs.h></STRONG>, which cannot be used in the same file as <STRONG><stdarg.h></STRONG>.
+ This implementation uses <STRONG><stdarg.h></STRONG> for both, because that header
+ is included in <STRONG><curses.h</STRONG>>.
+
+ <STRONG>o</STRONG> X/Open Curses, Issue 5 (December 2007) marked <STRONG>vwscanw</STRONG> (along with
+ <STRONG>vwprintw</STRONG> and the termcap interface) as withdrawn.
+
+ Both XSI and The Single Unix Specification, Version 2 state that these
+ functions return <STRONG>ERR</STRONG> or <STRONG>OK</STRONG>.
+
+ <STRONG>o</STRONG> Since the underlying <STRONG>scanf(3)</STRONG> 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.
+
+ <STRONG>o</STRONG> 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 <STRONG>vsscanf</STRONG> to scan the string, which returns <STRONG>EOF</STRONG> on error.
+
+ <STRONG>o</STRONG> Portable applications should only test if the return value is <STRONG>ERR</STRONG>,
+ since the <STRONG>OK</STRONG> 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.