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| <H1 class="no-header">curs_scanw 3x 2024-04-20 ncurses 6.5 Library calls</H1> |
| <PRE> |
| <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> - 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>*</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> |
| |
| <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> |
| <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. |
| |
| <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> |
| These functions return <STRONG>ERR</STRONG> upon failure and otherwise a count of |
| successful conversions; this quantity may be zero. |
| |
| 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 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-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> |
| 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. |
| |
| 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> 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> 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. |
| |
| <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. |
| |
| 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. |
| |
| |
| </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." |
| |
| 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>scanf(3)</STRONG>, <STRONG>vscanf(3)</STRONG> |
| |
| |
| |
| ncurses 6.5 2024-04-20 <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG> |
| </PRE> |
| <div class="nav"> |
| <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-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> |
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