ncurses 6.2 - patch 20210109
[ncurses.git] / doc / html / man / curs_scanw.3x.html
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30   * @Id: curs_scanw.3x,v 1.28 2020/10/24 09:29:26 tom Exp @
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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>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
58        <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>
59        <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>
60        <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>
61
62        <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>
63
64        /* obsolete */
65        <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>
66
67
68 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
69        The <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG> and <STRONG>mvscanw</STRONG> routines  are  analogous  to  <STRONG>scanf</STRONG>  [see
70        <STRONG>scanf(3)</STRONG>].   The  effect  of  these  routines is as though <STRONG>wgetstr</STRONG> were
71        called on the  window,  and  the  resulting  line  used  as  input  for
72        <STRONG>sscanf(3)</STRONG>.   Fields which do not map to a variable in the <EM>fmt</EM> field are
73        lost.
74
75        The <STRONG>vwscanw</STRONG> and <STRONG>vw_scanw</STRONG> routines are  analogous  to  <STRONG>vscanf(3)</STRONG>.   They
76        perform a <STRONG>wscanw</STRONG> using a variable argument list.  The third argument is
77        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>.
78
79
80 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
81        <STRONG>vwscanw</STRONG> returns <STRONG>ERR</STRONG> on failure and an integer equal to  the  number  of
82        fields scanned on success.
83
84        Applications  may  use the return value from the <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>
85        and <STRONG>mvwscanw</STRONG> routines to determine the  number  of  fields  which  were
86        mapped in the call.
87
88        Functions  with  a  "mv"  prefix  first perform a cursor movement using
89        <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
90        the window pointer is null.
91
92
93 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
94        While  <STRONG>scanw</STRONG>  was implemented in 4BSD, none of the BSD releases used it
95        until 4.4BSD (in a game).  That early version of curses was before  the
96        ANSI  C  standard.   It did not use &lt;varargs.h&gt;, though that was avail-
97        able.  In 1991 (a couple of years after SVr4 was  generally  available,
98        and  after  the C standard was published), other developers updated the
99        library, using &lt;stdarg.h&gt; internally in 4.4BSD curses.  Even with  this
100        improvement,  BSD  curses  did  not  use  function  prototypes (or even
101        declare functions) in the &lt;curses.h&gt; header until 1992.
102
103        SVr2 documented <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG> tersely as  "scanf  through  <EM>stdscr</EM>"  and
104        tersely as "scanf through <EM>win</EM>", respectively.
105
106        SVr3 added <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG>, with a three-line summary saying that
107        they were analogous to <STRONG>scanf(3)</STRONG>, explaining that the string which would
108        be  output  from  <STRONG>scanf(3)</STRONG> would instead be output using <STRONG>waddstr</STRONG> on the
109        given window.  SVr3 also added <STRONG>vwscanw</STRONG>, saying that the third parameter
110        is  a  <STRONG>va_list</STRONG>, defined in &lt;varargs.h&gt;, and referring the reader to the
111        manual  pages  for  <EM>varargs</EM>  and  <EM>vprintf</EM>  for  detailed  descriptions.
112        (Because the SVr3 documentation does not mention <EM>vscanf</EM>, that reference
113        to <EM>vprintf</EM> may not be an error).
114
115        SVr4  added  no  new  variations  of  <STRONG>scanw</STRONG>,  but  provided  for  using
116        &lt;varargs.h&gt; or &lt;stdarg.h&gt; to define the <STRONG>va_list</STRONG> type.
117
118        X/Open  Curses  added  <STRONG>vw_scanw</STRONG>  to  replace  <STRONG>vwscanw</STRONG>, stating that its
119        <STRONG>va_list</STRONG> definition requires &lt;stdarg.h&gt;.
120
121
122 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
123        In this implementation, <STRONG>vw_scanw</STRONG> and <STRONG>vwscanw</STRONG> are equivalent, to support
124        legacy applications.  However, the latter (<STRONG>vwscanw</STRONG>) is obsolete:
125
126        <STRONG>o</STRONG>   The  XSI Curses standard, Issue 4 described these functions, noting
127            that the function <STRONG>vwscanw</STRONG> is marked TO BE WITHDRAWN, and is  to  be
128            replaced by a function <STRONG>vw_scanw</STRONG> using the <STRONG>&lt;stdarg.h&gt;</STRONG> interface.
129
130        <STRONG>o</STRONG>   The  Single  Unix Specification, Version 2 states that <STRONG>vw_scanw</STRONG>  is
131            preferred  to  <STRONG>vwscanw</STRONG>  since   the   latter   requires   including
132            <STRONG>&lt;varargs.h&gt;</STRONG>,  which  cannot be used in the same file as <STRONG>&lt;stdarg.h&gt;</STRONG>.
133            This implementation uses <STRONG>&lt;stdarg.h&gt;</STRONG> for both, because  that  header
134            is included in <STRONG>&lt;curses.h</STRONG>&gt;.
135
136        <STRONG>o</STRONG>   X/Open  Curses,  Issue 5 (December 2007) marked <STRONG>vwscanw</STRONG> (along with
137            <STRONG>vwprintw</STRONG> and the termcap interface) as withdrawn.
138
139        Both XSI and The Single Unix Specification, Version 2 state that  these
140        functions return <STRONG>ERR</STRONG> or <STRONG>OK</STRONG>.
141
142        <STRONG>o</STRONG>   Since  the  underlying  <STRONG>scanf(3)</STRONG>  can  return  the  number of items
143            scanned, and the SVr4 code was documented to use this feature, this
144            is  probably  an  editing error which was introduced in XSI, rather
145            than being done intentionally.
146
147        <STRONG>o</STRONG>   This implementation returns the number of items scanned,  for  com-
148            patibility  with  SVr4  curses.   As  of  2018,  NetBSD curses also
149            returns the number of  items  scanned.   Both  ncurses  and  NetBSD
150            curses call <STRONG>vsscanf</STRONG> to scan the string, which returns <STRONG>EOF</STRONG> on error.
151
152        <STRONG>o</STRONG>   Portable  applications should only test if the return value is <STRONG>ERR</STRONG>,
153            since the <STRONG>OK</STRONG> value (zero) is likely to be misleading.
154
155            One possible way to get useful results would be to use a "%n"  con-
156            version  at  the  end of the format string to ensure that something
157            was processed.
158
159
160 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
161        <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>,
162        <STRONG>scanf(3)</STRONG>.
163
164
165
166                                                                 <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
167 </PRE>
168 <div class="nav">
169 <ul>
170 <li><a href="#h2-NAME">NAME</a></li>
171 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
172 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
173 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
174 <li><a href="#h2-HISTORY">HISTORY</a></li>
175 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
176 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
177 </ul>
178 </div>
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