ncurses 6.2 - patch 20200425
[ncurses.git] / doc / html / man / curs_scanw.3x.html
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42 <H1 class="no-header">curs_scanw 3x</H1>
43 <PRE>
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>
45
46
47
48
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
52
53
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55        <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
56
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>
62
63        /* obsolete */
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>
65
66
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
72        lost.
73
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>&lt;stdarg.h&gt;</STRONG>.
77
78
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.
82
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
85        mapped in the call.
86
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.
90
91
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 &lt;varargs.h&gt;, 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 &lt;stdarg.h&gt; internally in 4.4BSD curses.  Even with  this
99        improvement,  BSD  curses  did  not  use  function  prototypes (or even
100        declare functions) in the &lt;curses.h&gt; header until 1992.
101
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.
104
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 &lt;varargs.h&gt;, 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).
113
114        SVr4  added  no  new  variations  of  <STRONG>scanw</STRONG>,  but  provided  for  using
115        &lt;varargs.h&gt; or &lt;stdarg.h&gt; to define the <STRONG>va_list</STRONG> type.
116
117        X/Open  Curses  added  <STRONG>vw_scanw</STRONG>  to  replace  <STRONG>vwscanw</STRONG>, stating that its
118        <STRONG>va_list</STRONG> definition requires &lt;stdarg.h&gt;.
119
120
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:
124
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>&lt;stdarg.h&gt;</STRONG> interface.
128
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>&lt;varargs.h&gt;</STRONG>,  which  cannot be used in the same file as <STRONG>&lt;stdarg.h&gt;</STRONG>.
132            This implementation uses <STRONG>&lt;stdarg.h&gt;</STRONG> for both, because  that  header
133            is included in <STRONG>&lt;curses.h</STRONG>&gt;.
134
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.
137
138        Both XSI and The Single Unix Specification, Version 2 state that  these
139        functions return <STRONG>ERR</STRONG> or <STRONG>OK</STRONG>.
140
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.
145
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.
150
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.
153
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
156            was processed.
157
158
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>.
162
163
164
165                                                                 <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
166 </PRE>
167 <div class="nav">
168 <ul>
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>
176 </ul>
177 </div>
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