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<H1 class="no-header">curs_scanw 3x</H1>
<PRE>
<STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG> <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>, <STRONG>mvwscanw</STRONG>, <STRONG>vwscanw</STRONG>, <STRONG>vw_scanw</STRONG> - convert formatted
input from a <STRONG>curses</STRONG> window
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>int</STRONG> <STRONG>scanw(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
<STRONG>int</STRONG> <STRONG>wscanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
<STRONG>int</STRONG> <STRONG>mvscanw(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
<STRONG>int</STRONG> <STRONG>mvwscanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
<STRONG>int</STRONG> <STRONG>vw_scanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>va_list</STRONG> <EM>varglist</EM><STRONG>);</STRONG>
/* obsolete */
<STRONG>int</STRONG> <STRONG>vwscanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>va_list</STRONG> <EM>varglist</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
The <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG> and <STRONG>mvscanw</STRONG> routines are analogous to <STRONG>scanf</STRONG> [see
<STRONG>scanf(3)</STRONG>]. The effect of these routines is as though <STRONG>wgetstr</STRONG> were
called on the window, and the resulting line used as input for
<STRONG>sscanf(3)</STRONG>. Fields which do not map to a variable in the <EM>fmt</EM> field are
lost.
The <STRONG>vwscanw</STRONG> and <STRONG>vw_scanw</STRONG> routines are analogous to <STRONG>vscanf(3)</STRONG>. They
perform a <STRONG>wscanw</STRONG> using a variable argument list. The third argument is
a <EM>va</EM><STRONG>_</STRONG><EM>list</EM>, a pointer to a list of arguments, as defined in <STRONG><stdarg.h></STRONG>.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
<STRONG>vwscanw</STRONG> returns <STRONG>ERR</STRONG> on failure and an integer equal to the number of
fields scanned on success.
Applications may use the return value from the <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>
and <STRONG>mvwscanw</STRONG> routines to determine the number of fields which were
mapped in the call.
Functions with a "mv" prefix first perform a cursor movement using
<STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
the window pointer is null.
</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
While <STRONG>scanw</STRONG> was implemented in 4BSD, none of the BSD releases used it
until 4.4BSD (in a game). That early version of curses was before the
ANSI C standard. It did not use <varargs.h>, though that was
available. In 1991 (a couple of years after SVr4 was generally
available, and after the C standard was published), other developers
updated the library, using <stdarg.h> internally in 4.4BSD curses.
Even with this improvement, BSD curses did not use function prototypes
(or even declare functions) in the <curses.h> header until 1992.
SVr2 documented <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG> tersely as "scanf through <EM>stdscr</EM>" and
tersely as "scanf through <EM>win</EM>", respectively.
SVr3 added <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG>, with a three-line summary saying that
they were analogous to <STRONG>scanf(3)</STRONG>, explaining that the string which would
be output from <STRONG>scanf(3)</STRONG> would instead be output using <STRONG>waddstr</STRONG> on the
given window. SVr3 also added <STRONG>vwscanw</STRONG>, saying that the third parameter
is a <STRONG>va_list</STRONG>, defined in <varargs.h>, and referring the reader to the
manual pages for <EM>varargs</EM> and <EM>vprintf</EM> for detailed descriptions.
(Because the SVr3 documentation does not mention <EM>vscanf</EM>, that reference
to <EM>vprintf</EM> may not be an error).
SVr4 added no new variations of <STRONG>scanw</STRONG>, but provided for using
<varargs.h> or <stdarg.h> to define the <STRONG>va_list</STRONG> type.
X/Open Curses added <STRONG>vw_scanw</STRONG> to replace <STRONG>vwscanw</STRONG>, stating that its
<STRONG>va_list</STRONG> definition requires <stdarg.h>.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
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
compatibility 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"
conversion at the end of the format string to ensure that something
was processed.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_getstr.3x.html">curs_getstr(3x)</A></STRONG>, <STRONG><A HREF="curs_printw.3x.html">curs_printw(3x)</A></STRONG>, <STRONG><A HREF="curs_termcap.3x.html">curs_termcap(3x)</A></STRONG>,
<STRONG>scanf(3)</STRONG>.
<STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
</PRE>
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<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
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