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  37 <TITLE>curs_scanw 3x 2023-11-25 ncurses 6.4 Library calls</TITLE>
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  42 <H1 class="no-header">curs_scanw 3x 2023-11-25 ncurses 6.4 Library calls</H1>
  43 <PRE>
  44 <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>
  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> - read formatted
  51        input from a <EM>curses</EM> 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        <EM>/*</EM> <EM>obsolete</EM> <EM>*/</EM>
  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 <STRONG>va_list</STRONG>, 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-PORTABILITY">PORTABILITY</a></H2><PRE>
  94        In this implementation, <STRONG>vw_scanw</STRONG> and <STRONG>vwscanw</STRONG> are equivalent, to support
  95        legacy applications.  However, the latter (<STRONG>vwscanw</STRONG>) is obsolete:
  96
  97        <STRONG>o</STRONG>   The XSI Curses standard, Issue 4 described these functions,  noting
  98            that  the  function <STRONG>vwscanw</STRONG> is marked TO BE WITHDRAWN, and is to be
  99            replaced by a function <STRONG>vw_scanw</STRONG> using the <STRONG>&lt;stdarg.h&gt;</STRONG> interface.
 100
 101        <STRONG>o</STRONG>   The Single Unix Specification, Version 2 states that  <STRONG>vw_scanw</STRONG>   is
 102            preferred   to   <STRONG>vwscanw</STRONG>   since   the  latter  requires  including
 103            <STRONG>&lt;varargs.h&gt;</STRONG>, which cannot be used in the same file  as  <STRONG>&lt;stdarg.h&gt;</STRONG>.
 104            This  implementation  uses <STRONG>&lt;stdarg.h&gt;</STRONG> for both, because that header
 105            is included in <STRONG>&lt;curses.h</STRONG>&gt;.
 106
 107        <STRONG>o</STRONG>   X/Open Curses, Issue 5 (December 2007) marked <STRONG>vwscanw</STRONG>  (along  with
 108            <STRONG>vwprintw</STRONG> and the termcap interface) as withdrawn.
 109
 110        Both  XSI and The Single Unix Specification, Version 2 state that these
 111        functions return <STRONG>ERR</STRONG> or <STRONG>OK</STRONG>.
 112
 113        <STRONG>o</STRONG>   Since the underlying  <STRONG>scanf(3)</STRONG>  can  return  the  number  of  items
 114            scanned, and the SVr4 code was documented to use this feature, this
 115            is probably an editing error which was introduced  in  XSI,  rather
 116            than being done intentionally.
 117
 118        <STRONG>o</STRONG>   This  implementation  returns  the  number  of  items  scanned, for
 119            compatibility with SVr4 curses.  As of  2018,  NetBSD  curses  also
 120            returns  the  number  of  items  scanned.   Both ncurses and NetBSD
 121            curses call <STRONG>vsscanf</STRONG> to scan the string, which returns <STRONG>EOF</STRONG> on error.
 122
 123        <STRONG>o</STRONG>   Portable applications should only test if the return value is  <STRONG>ERR</STRONG>,
 124            since the <STRONG>OK</STRONG> value (zero) is likely to be misleading.
 125
 126            One  possible  way  to  get  useful  results would be to use a "%n"
 127            conversion at the end of the format string to ensure that something
 128            was processed.
 129
 130
 131 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
 132        While  <STRONG>scanw</STRONG>  was implemented in 4BSD, none of the BSD releases used it
 133        until 4.4BSD (in a game).  That early version of curses was before  the
 134        ANSI  C  standard.   It  did  not  use  &lt;varargs.h&gt;,  though  that  was
 135        available.  In 1991  (a  couple  of  years  after  SVr4  was  generally
 136        available,  and  after  the C standard was published), other developers
 137        updated the library, using  &lt;stdarg.h&gt;  internally  in  4.4BSD  curses.
 138        Even  with this improvement, BSD curses did not use function prototypes
 139        (or even declare functions) in the &lt;curses.h&gt; header until 1992.
 140
 141        SVr2 documented <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG> tersely as  "scanf  through  <EM>stdscr</EM>"  and
 142        tersely as "scanf through <EM>win</EM>", respectively.
 143
 144        SVr3 added <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG>, with a three-line summary saying that
 145        they were analogous to <STRONG>scanf(3)</STRONG>, explaining that the string which would
 146        be  output  from  <STRONG>scanf(3)</STRONG> would instead be output using <STRONG>waddstr</STRONG> on the
 147        given window.  SVr3 also added <STRONG>vwscanw</STRONG>, saying that the third parameter
 148        is  a  <STRONG>va_list</STRONG>, defined in &lt;varargs.h&gt;, and referring the reader to the
 149        manual  pages  for  <EM>varargs</EM>  and  <STRONG>vprintf</STRONG>  for  detailed  descriptions.
 150        (Because the SVr3 documentation does not mention <STRONG>vscanf</STRONG>, that reference
 151        to <STRONG>vprintf</STRONG> may not be an error).
 152
 153        SVr4  added  no  new  variations  of  <STRONG>scanw</STRONG>,  but  provided  for  using
 154        &lt;varargs.h&gt; or &lt;stdarg.h&gt; to define the <STRONG>va_list</STRONG> type.
 155
 156        X/Open  Curses  added  <STRONG>vw_scanw</STRONG>  to  replace  <STRONG>vwscanw</STRONG>, stating that its
 157        <STRONG>va_list</STRONG> definition requires &lt;stdarg.h&gt;.
 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 ncurses 6.4                       2023-11-25                    <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-PORTABILITY">PORTABILITY</a></li>
 175 <li><a href="#h2-HISTORY">HISTORY</a></li>
 176 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
 177 </ul>
 178 </div>
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