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30 * @Id: curs_scanw.3x,v 1.27 2020/03/15 00:14:30 tom Exp @
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42 <H1 class="no-header">curs_scanw 3x</H1>
44 <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG> <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
49 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
50 <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>, <STRONG>mvwscanw</STRONG>, <STRONG>vwscanw</STRONG>, <STRONG>vw_scanw</STRONG> - convert formatted
51 input from a <STRONG>curses</STRONG> window
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
57 <STRONG>int</STRONG> <STRONG>scanw(const</STRONG> <STRONG>char</STRONG> <STRONG>*fmt,</STRONG> <STRONG>...);</STRONG>
58 <STRONG>int</STRONG> <STRONG>wscanw(WINDOW</STRONG> <STRONG>*win,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*fmt,</STRONG> <STRONG>...);</STRONG>
59 <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>
60 <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>
61 <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>
64 <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>
67 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
68 The <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG> and <STRONG>mvscanw</STRONG> routines are analogous to <STRONG>scanf</STRONG> [see
69 <STRONG>scanf(3)</STRONG>]. The effect of these routines is as though <STRONG>wgetstr</STRONG> were
70 called on the window, and the resulting line used as input for
71 <STRONG>sscanf(3)</STRONG>. Fields which do not map to a variable in the <EM>fmt</EM> field are
74 The <STRONG>vwscanw</STRONG> and <STRONG>vw_scanw</STRONG> routines are analogous to <STRONG>vscanf(3)</STRONG>. They
75 perform a <STRONG>wscanw</STRONG> using a variable argument list. The third argument is
76 a <EM>va</EM><STRONG>_</STRONG><EM>list</EM>, a pointer to a list of arguments, as defined in <STRONG><stdarg.h></STRONG>.
79 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
80 <STRONG>vwscanw</STRONG> returns <STRONG>ERR</STRONG> on failure and an integer equal to the number of
81 fields scanned on success.
83 Applications may use the return value from the <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>
84 and <STRONG>mvwscanw</STRONG> routines to determine the number of fields which were
87 Functions with a "mv" prefix first perform a cursor movement using
88 <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
89 the window pointer is null.
92 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
93 While <STRONG>scanw</STRONG> was implemented in 4BSD, none of the BSD releases used it
94 until 4.4BSD (in a game). That early version of curses was before the
95 ANSI C standard. It did not use <varargs.h>, though that was avail-
96 able. In 1991 (a couple of years after SVr4 was generally available,
97 and after the C standard was published), other developers updated the
98 library, using <stdarg.h> internally in 4.4BSD curses. Even with this
99 improvement, BSD curses did not use function prototypes (or even
100 declare functions) in the <curses.h> header until 1992.
102 SVr2 documented <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG> tersely as "scanf through <EM>stdscr</EM>" and
103 tersely as "scanf through <EM>win</EM>", respectively.
105 SVr3 added <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG>, with a three-line summary saying that
106 they were analogous to <STRONG>scanf(3)</STRONG>, explaining that the string which would
107 be output from <STRONG>scanf(3)</STRONG> would instead be output using <STRONG>waddstr</STRONG> on the
108 given window. SVr3 also added <STRONG>vwscanw</STRONG>, saying that the third parameter
109 is a <STRONG>va_list</STRONG>, defined in <varargs.h>, and referring the reader to the
110 manual pages for <EM>varargs</EM> and <EM>vprintf</EM> for detailed descriptions.
111 (Because the SVr3 documentation does not mention <EM>vscanf</EM>, that reference
112 to <EM>vprintf</EM> may not be an error).
114 SVr4 added no new variations of <STRONG>scanw</STRONG>, but provided for using
115 <varargs.h> or <stdarg.h> to define the <STRONG>va_list</STRONG> type.
117 X/Open Curses added <STRONG>vw_scanw</STRONG> to replace <STRONG>vwscanw</STRONG>, stating that its
118 <STRONG>va_list</STRONG> definition requires <stdarg.h>.
121 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
122 In this implementation, <STRONG>vw_scanw</STRONG> and <STRONG>vwscanw</STRONG> are equivalent, to support
123 legacy applications. However, the latter (<STRONG>vwscanw</STRONG>) is obsolete:
125 <STRONG>o</STRONG> The XSI Curses standard, Issue 4 described these functions, noting
126 that the function <STRONG>vwscanw</STRONG> is marked TO BE WITHDRAWN, and is to be
127 replaced by a function <STRONG>vw_scanw</STRONG> using the <STRONG><stdarg.h></STRONG> interface.
129 <STRONG>o</STRONG> The Single Unix Specification, Version 2 states that <STRONG>vw_scanw</STRONG> is
130 preferred to <STRONG>vwscanw</STRONG> since the latter requires including
131 <STRONG><varargs.h></STRONG>, which cannot be used in the same file as <STRONG><stdarg.h></STRONG>.
132 This implementation uses <STRONG><stdarg.h></STRONG> for both, because that header
133 is included in <STRONG><curses.h</STRONG>>.
135 <STRONG>o</STRONG> X/Open Curses, Issue 5 (December 2007) marked <STRONG>vwscanw</STRONG> (along with
136 <STRONG>vwprintw</STRONG> and the termcap interface) as withdrawn.
138 Both XSI and The Single Unix Specification, Version 2 state that these
139 functions return <STRONG>ERR</STRONG> or <STRONG>OK</STRONG>.
141 <STRONG>o</STRONG> Since the underlying <STRONG>scanf(3)</STRONG> can return the number of items
142 scanned, and the SVr4 code was documented to use this feature, this
143 is probably an editing error which was introduced in XSI, rather
144 than being done intentionally.
146 <STRONG>o</STRONG> This implementation returns the number of items scanned, for com-
147 patibility with SVr4 curses. As of 2018, NetBSD curses also
148 returns the number of items scanned. Both ncurses and NetBSD
149 curses call <STRONG>vsscanf</STRONG> to scan the string, which returns <STRONG>EOF</STRONG> on error.
151 <STRONG>o</STRONG> Portable applications should only test if the return value is <STRONG>ERR</STRONG>,
152 since the <STRONG>OK</STRONG> value (zero) is likely to be misleading.
154 One possible way to get useful results would be to use a "%n" con-
155 version at the end of the format string to ensure that something
159 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
160 <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>,
161 <STRONG>scanf(3)</STRONG>.
165 <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
169 <li><a href="#h2-NAME">NAME</a></li>
170 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
171 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
172 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
173 <li><a href="#h2-HISTORY">HISTORY</a></li>
174 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
175 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>