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+ * Copyright (c) 1998-2015,2017 Free Software Foundation, Inc. *
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- * @Id: curs_touch.3x,v 1.16 2015/12/05 23:43:00 tom Exp @
+ * @Id: curs_touch.3x,v 1.20 2017/11/25 16:19:42 tom Exp @
-->
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X/Open does not define any error conditions. In this implementation
- <STRONG>is_linetouched</STRONG>
- returns an error if the window pointer is null, or if the
- line number is outside the window. Note that ERR is dis-
- tinct from <STRONG>TRUE</STRONG> and <STRONG>FALSE</STRONG>, which are the normal return val-
- ues of this function.
+ <STRONG>is_linetouched</STRONG>
+ returns an error if the window pointer is null, or if the line
+ number is outside the window.
- <STRONG>wtouchln</STRONG>
- returns an error if the window pointer is null, or if the
- line number is outside the window.
+ The constant <STRONG>ERR</STRONG> is distinct from <STRONG>TRUE</STRONG> and <STRONG>FALSE</STRONG>, which are the
+ normal return values of this function. Because the function
+ returns a <STRONG>bool</STRONG>, returning <STRONG>ERR</STRONG> (which is neither <STRONG>TRUE</STRONG> nor <STRONG>FALSE</STRONG>)
+ may not be supported by the compiler.
+
+ To provide error-checking and also match the X/Open function
+ prototype, the <STRONG>ERR</STRONG> is provided by a macro named <STRONG>is_linetouched</STRONG>.
+ The actual function returns <STRONG>FALSE</STRONG> when it detects an error.
+
+ <STRONG>wtouchln</STRONG>
+ returns an error if the window pointer is null, or if the line
+ number is outside the window.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- The XSI Curses standard, Issue 4 describes these functions.
+ These functions were introduced by SVr4. The Solaris curses header
+ file, for instance, defines both an actual function and macro for each.
+ The macros give the same result as the actual functions. SVr4 curses
+ does not check the window parameter <EM>win</EM> to ensure that it is not <STRONG>NULL</STRONG>;
+ otherwise this implementation behaves the same as SVr4.
- Some historic curses implementations had, as an undocumented feature,
- the ability to do the equivalent of <STRONG>clearok(...,</STRONG> <STRONG>1)</STRONG> by saying <STRONG>touch-</STRONG>
- <STRONG>win(stdscr)</STRONG> or <STRONG>clear(stdscr)</STRONG>. This will not work under ncurses.
+ The XSI Curses standard, Issue 4 describes these functions, but defines
+ no error conditions.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
- Note that all routines except <STRONG>wtouchln</STRONG> may be macros.
+ All of these routines except <STRONG>wtouchln</STRONG> may be macros.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
projects / ncurses.git / blobdiff