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-<H1 class="no-header">curs_scanw 3x</H1>
+<H1 class="no-header">curs_scanw 3x 2024-04-20 ncurses 6.4 Library calls</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>
+<STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
Library calls <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
+ <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>, <STRONG>mvwscanw</STRONG>, <STRONG>vwscanw</STRONG>, <STRONG>vw_scanw</STRONG> - read formatted
+ input from a <EM>curses</EM> 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>*fmt,</STRONG> <STRONG>...);</STRONG>
- <STRONG>int</STRONG> <STRONG>wscanw(WINDOW</STRONG> <STRONG>*win,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*fmt,</STRONG> <STRONG>...);</STRONG>
- <STRONG>int</STRONG> <STRONG>mvscanw(int</STRONG> <STRONG>y,</STRONG> <STRONG>int</STRONG> <STRONG>x,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*fmt,</STRONG> <STRONG>...);</STRONG>
- <STRONG>int</STRONG> <STRONG>mvwscanw(WINDOW</STRONG> <STRONG>*win,</STRONG> <STRONG>int</STRONG> <STRONG>y,</STRONG> <STRONG>int</STRONG> <STRONG>x,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*fmt,</STRONG> <STRONG>...);</STRONG>
- <STRONG>int</STRONG> <STRONG>vw_scanw(WINDOW</STRONG> <STRONG>*win,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*fmt,</STRONG> <STRONG>va_list</STRONG> <STRONG>varglist);</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>*win,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*fmt,</STRONG> <STRONG>va_list</STRONG> <STRONG>varglist);</STRONG>
+ <EM>/*</EM> <EM>obsolete</EM> <EM>*/</EM>
+ <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.
+ <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG> are analogous to <STRONG>scanf(3)</STRONG>. In
+ effect, they call <STRONG><A HREF="curs_getstr.3x.html">wgetstr(3x)</A></STRONG> with <EM>win</EM> (or <STRONG>stdscr</STRONG>) as its first
+ argument, then attempt conversion of the resulting string with
+ <STRONG>vsscanf(3)</STRONG>. Fields in the string that do not map to a variable in the
+ <EM>fmt</EM> parameter are discarded.
- 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>.
+ <STRONG>vwscanw</STRONG> and <STRONG>vw_scanw</STRONG> are analogous to <STRONG>vscanf(3)</STRONG>, and 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 <EM>stdarg.h</EM>.
</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.
+ These functions return <STRONG>ERR</STRONG> upon failure and otherwise a count of
+ successful conversions; this quantity may be zero.
- 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.
+ In <EM>ncurses</EM>, failure occurs if <STRONG>vsscanf(3)</STRONG> returns <STRONG>EOF</STRONG>, or if the window
+ pointer <EM>win</EM> is null.
- 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.
+ Functions prefixed with "mv" first perform cursor movement and fail if
+ the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries.
-</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 avail-
- able. 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-NOTES">NOTES</a></H2><PRE>
+ No wide character counterpart functions are defined by the "wide"
+ <EM>ncurses</EM> configuration nor by any standard. They are unnecessary: to
+ retrieve and convert a wide-character string from a <EM>curses</EM> terminal
+ keyboard, use these functions with the <STRONG>scanf(3)</STRONG> conversions "%lc" and
+ "%ls" for wide characters and strings, respectively.
+
+ <EM>ncurses</EM> implements <STRONG>vsscanf(3)</STRONG> internally if it is unavailable when the
+ library is configured.
</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:
+ X/Open Curses, Issue 4 describes these functions. It specifies no
+ error conditions for them.
+
+ <EM>ncurses</EM> defines <STRONG>vw_scanw</STRONG> and <STRONG>vwscanw</STRONG> identically to support legacy
+ applications. However, the latter is obsolete.
+
+ <STRONG>o</STRONG> X/Open Curses, Issue 4 Version 2 (1996), marked <STRONG>vwscanw</STRONG> as
+ requiring <EM>varargs.h</EM> and "TO BE WITHDRAWN", and specified <STRONG>vw_scanw</STRONG>
+ using the <EM>stdarg.h</EM> interface.
+
+ <STRONG>o</STRONG> X/Open Curses, Issue 5, Draft 2 (December 2007) marked <STRONG>vwscanw</STRONG>
+ (along with <STRONG>vwscanw</STRONG> and the <EM>termcap</EM> interface) as withdrawn. After
+ incorporating review comments, this became X/Open Curses, Issue 7
+ (2009).
+
+ <STRONG>o</STRONG> <EM>ncurses</EM> provides <STRONG>vwscanw</STRONG>, but marks it as deprecated.
- <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.
+ X/Open Curses Issues 4 and 7 both state that these functions return <STRONG>ERR</STRONG>
+ or <STRONG>OK</STRONG>. This is likely an erratum.
- <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> Since the underlying <STRONG>scanf(3)</STRONG> returns the number of successful
+ conversions, and SVr4 <EM>curses</EM> was documented to use this feature,
+ this may have been an editorial solecism introduced by X/Open,
+ rather than an intentional change.
- <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.
+ <STRONG>o</STRONG> This implementation retains compatibility with SVr4 <EM>curses</EM>. As of
+ 2018, NetBSD <EM>curses</EM> also returns the number of successful
+ conversions. Both <EM>ncurses</EM> and NetBSD <EM>curses</EM> call <STRONG>vsscanf(3)</STRONG> to
+ scan the string, which returns <STRONG>EOF</STRONG> on error.
- Both XSI and The Single Unix Specification, Version 2 state that these
- functions return <STRONG>ERR</STRONG> or <STRONG>OK</STRONG>.
+ <STRONG>o</STRONG> Portable applications should test only if the return value is <STRONG>ERR</STRONG>,
+ and not compare it to <STRONG>OK</STRONG>, since that value (zero) might be
+ misleading.
- <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.
+ One portable way to get useful results would be to use a "%n"
+ conversion at the end of the format string, and check the value of
+ the corresponding variable to determine how many conversions
+ succeeded.
- <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.
+</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
+ <STRONG>scanw</STRONG> was implemented in 4BSD (November 1980); that early version of
+ <EM>curses</EM> preceded the ANSI C standard of 1989. The function was unused
+ in Berkeley distributions for over ten years, until 4.4BSD, which
+ employed it in a game. The 4BSD <STRONG>scanw</STRONG> did not use <EM>varargs.h</EM>, though
+ that had been available since Seventh Edition Unix (1979). In 1991 (a
+ couple of years after SVr4 was generally available, and after the C
+ standard was published), other developers updated the library, using
+ <EM>stdarg.h</EM> internally in 4.4BSD <EM>curses</EM>. Even with this improvement, BSD
+ <EM>curses</EM> did not use function prototypes (nor even declare functions) in
+ <EM>curses.h</EM> until 1992.
+
+ SVr2 (1984) documented <STRONG>scanw</STRONG> and <STRONG>wscanw</STRONG> tersely as "scanf through
+ <STRONG>stdscr</STRONG>" and "scanf through <EM>win</EM>", respectively.
+
+ SVr3 (1987) added <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG>, stating
+
+ "[t]hese routines correspond to <STRONG>scanf(3S)</STRONG>, as do their arguments
+ and return values. <STRONG>wgetstr</STRONG>() is called on the window, and the
+ resulting line is used as input for the scan."
- 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.
+ SVr3 also implemented <STRONG>vwscanw</STRONG>, describing its third parameter as a
+ <EM>va</EM><STRONG>_</STRONG><EM>list</EM>, defined in <EM>varargs.h</EM>, and referred 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>, the reference to <EM>vprintf</EM>
+ might not be an error).
+
+ SVr4 (1989) introduced no new variations of <EM>scanw</EM>, but provided for
+ using either <EM>varargs.h</EM> or <EM>stdarg.h</EM> to define the <EM>va</EM><STRONG>_</STRONG><EM>list</EM> type.
+
+ X/Open Curses, Issue 4 (1995), defined <EM>vw</EM><STRONG>_</STRONG><EM>scanw</EM> to replace <EM>vwscanw</EM>,
+ stating that its <EM>va</EM><STRONG>_</STRONG><EM>list</EM> type is defined in <EM>stdarg.h</EM>.
</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="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>scanf(3)</STRONG>, <STRONG>vscanf(3)</STRONG>
-
<STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
+
ncurses 6.4 2024-04-20 <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<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-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
+<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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