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In 70 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 71 argument, then attempt conversion of the resulting string with 72 <STRONG>vsscanf(3)</STRONG>. Fields in the string that do not map to a variable in the 73 <EM>fmt</EM> parameter are discarded. 74 75 <STRONG>vwscanw</STRONG> and <STRONG>vw_scanw</STRONG> are analogous to <STRONG>vscanf(3)</STRONG>, and perform a <STRONG>wscanw</STRONG> 76 using a variable argument list. The third argument is a <EM>va</EM><STRONG>_</STRONG><EM>list</EM>, a 77 pointer to a list of arguments, as defined in <EM>stdarg.h</EM>. 78 79 80</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE> 81 These functions return <STRONG>ERR</STRONG> upon failure and otherwise a count of 82 successful conversions; this quantity may be zero. 83 84 In <EM>ncurses</EM>, failure occurs if <STRONG>vsscanf(3)</STRONG> returns <STRONG>EOF</STRONG>, or if the window 85 pointer <EM>win</EM> is null. 86 87 Functions prefixed with "mv" first perform cursor movement and fail if 88 the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries. 89 90 91</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE> 92 No wide character counterpart functions are defined by the "wide" 93 <EM>ncurses</EM> configuration nor by any standard. They are unnecessary: to 94 retrieve and convert a wide-character string from a <EM>curses</EM> terminal 95 keyboard, use these functions with the <STRONG>scanf(3)</STRONG> conversions "%lc" and 96 "%ls" for wide characters and strings, respectively. 97 98 <EM>ncurses</EM> implements <STRONG>vsscanf(3)</STRONG> internally if it is unavailable when the 99 library is configured. 100 101 102</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE> 103 X/Open Curses, Issue 4 describes these functions. It specifies no 104 error conditions for them. 105 106 <EM>ncurses</EM> defines <STRONG>vw_scanw</STRONG> and <STRONG>vwscanw</STRONG> identically to support legacy 107 applications. However, the latter is obsolete. 108 109 <STRONG>o</STRONG> X/Open Curses, Issue 4 Version 2 (1996), marked <STRONG>vwscanw</STRONG> as 110 requiring <EM>varargs.h</EM> and "TO BE WITHDRAWN", and specified <STRONG>vw_scanw</STRONG> 111 using the <EM>stdarg.h</EM> interface. 112 113 <STRONG>o</STRONG> X/Open Curses, Issue 5, Draft 2 (December 2007) marked <STRONG>vwscanw</STRONG> 114 (along with <STRONG>vwscanw</STRONG> and the <EM>termcap</EM> interface) as withdrawn. After 115 incorporating review comments, this became X/Open Curses, Issue 7 116 (2009). 117 118 <STRONG>o</STRONG> <EM>ncurses</EM> provides <STRONG>vwscanw</STRONG>, but marks it as deprecated. 119 120 X/Open Curses Issues 4 and 7 both state that these functions return <STRONG>ERR</STRONG> 121 or <STRONG>OK</STRONG>. This is likely an erratum. 122 123 <STRONG>o</STRONG> Since the underlying <STRONG>scanf(3)</STRONG> returns the number of successful 124 conversions, and SVr4 <EM>curses</EM> was documented to use this feature, 125 this may have been an editorial solecism introduced by X/Open, 126 rather than an intentional change. 127 128 <STRONG>o</STRONG> This implementation retains compatibility with SVr4 <EM>curses</EM>. As of 129 2018, NetBSD <EM>curses</EM> also returns the number of successful 130 conversions. Both <EM>ncurses</EM> and NetBSD <EM>curses</EM> call <STRONG>vsscanf(3)</STRONG> to 131 scan the string, which returns <STRONG>EOF</STRONG> on error. 132 133 <STRONG>o</STRONG> Portable applications should test only if the return value is <STRONG>ERR</STRONG>, 134 and not compare it to <STRONG>OK</STRONG>, since that value (zero) might be 135 misleading. 136 137 One portable way to get useful results would be to use a "%n" 138 conversion at the end of the format string, and check the value of 139 the corresponding variable to determine how many conversions 140 succeeded. 141 142 143</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE> 144 <STRONG>scanw</STRONG> was implemented in 4BSD (November 1980); that early version of 145 <EM>curses</EM> preceded the ANSI C standard of 1989. The function was unused 146 in Berkeley distributions for over ten years, until 4.4BSD, which 147 employed it in a game. The 4BSD <STRONG>scanw</STRONG> did not use <EM>varargs.h</EM>, though 148 that had been available since Seventh Edition Unix (1979). In 1991 (a 149 couple of years after SVr4 was generally available, and after the C 150 standard was published), other developers updated the library, using 151 <EM>stdarg.h</EM> internally in 4.4BSD <EM>curses</EM>. Even with this improvement, BSD 152 <EM>curses</EM> did not use function prototypes (nor even declare functions) in 153 <EM>curses.h</EM> until 1992. 154 155 SVr2 (1984) documented <STRONG>scanw</STRONG> and <STRONG>wscanw</STRONG> tersely as "scanf through 156 <STRONG>stdscr</STRONG>" and "scanf through <EM>win</EM>", respectively. 157 158 SVr3 (1987) added <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG>, stating 159 160 "[t]hese routines correspond to <STRONG>scanf(3S)</STRONG>, as do their arguments 161 and return values. <STRONG>wgetstr</STRONG>() is called on the window, and the 162 resulting line is used as input for the scan." 163 164 SVr3 also implemented <STRONG>vwscanw</STRONG>, describing its third parameter as a 165 <EM>va</EM><STRONG>_</STRONG><EM>list</EM>, defined in <EM>varargs.h</EM>, and referred the reader to the manual 166 pages for <EM>varargs</EM> and <EM>vprintf</EM> for detailed descriptions. (Because the 167 SVr3 documentation does not mention <EM>vscanf</EM>, the reference to <EM>vprintf</EM> 168 might not be an error). 169 170 SVr4 (1989) introduced no new variations of <EM>scanw</EM>, but provided for 171 using either <EM>varargs.h</EM> or <EM>stdarg.h</EM> to define the <EM>va</EM><STRONG>_</STRONG><EM>list</EM> type. 172 173 X/Open Curses, Issue 4 (1995), defined <EM>vw</EM><STRONG>_</STRONG><EM>scanw</EM> to replace <EM>vwscanw</EM>, 174 stating that its <EM>va</EM><STRONG>_</STRONG><EM>list</EM> type is defined in <EM>stdarg.h</EM>. 175 176 177</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> 178 <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> 179 180 181 182ncurses 6.5 2024-04-20 <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG> 183</PRE> 184<div class="nav"> 185<ul> 186<li><a href="#h2-NAME">NAME</a></li> 187<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li> 188<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li> 189<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li> 190<li><a href="#h2-NOTES">NOTES</a></li> 191<li><a href="#h2-PORTABILITY">PORTABILITY</a></li> 192<li><a href="#h2-HISTORY">HISTORY</a></li> 193<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> 194</ul> 195</div> 196</BODY> 197</HTML> 198