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30 * @Id: curs_variables.3x,v 1.35 2023/12/16 21:05:52 tom Exp @
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42 <H1 class="no-header">curs_variables 3x 2023-12-16 ncurses 6.4 Library calls</H1>
44 <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
49 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
50 <EM>bool</EM>, <EM>chtype</EM>, <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM>, <EM>attr</EM><STRONG>_</STRONG><EM>t</EM>, <EM>WINDOW</EM>, <STRONG>TRUE</STRONG>, <STRONG>FALSE</STRONG>, <STRONG>ERR</STRONG>, <STRONG>OK</STRONG>, <STRONG>COLORS</STRONG>,
51 <STRONG>COLOR_PAIRS</STRONG>, <STRONG>COLS</STRONG>, <STRONG>ESCDELAY</STRONG>, <STRONG>LINES</STRONG>, <STRONG>TABSIZE</STRONG>, <STRONG>curscr</STRONG>, <STRONG>newscr</STRONG>, <STRONG>stdscr</STRONG> -
52 <EM>curses</EM> data types, constants, and global variables
55 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
56 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
58 <EM>/*</EM> <EM>data</EM> <EM>types</EM> <EM>*/</EM>
59 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>bool;</STRONG>
60 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>chtype;</STRONG>
61 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>cchar_t;</STRONG>
62 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>attr_t;</STRONG>
63 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>WINDOW;</STRONG>
65 <EM>/*</EM> <EM>constants</EM> <EM>*/</EM>
66 <STRONG>const</STRONG> <STRONG>bool</STRONG> <STRONG>TRUE;</STRONG>
67 <STRONG>const</STRONG> <STRONG>bool</STRONG> <STRONG>FALSE;</STRONG>
69 <STRONG>const</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>ERR;</STRONG>
70 <STRONG>const</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>OK;</STRONG>
72 <EM>/*</EM> <EM>variables</EM> <EM>*/</EM>
73 <STRONG>int</STRONG> <STRONG>COLOR_PAIRS;</STRONG>
74 <STRONG>int</STRONG> <STRONG>COLORS;</STRONG>
75 <STRONG>int</STRONG> <STRONG>COLS;</STRONG>
76 <STRONG>int</STRONG> <STRONG>LINES;</STRONG>
77 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>curscr;</STRONG>
78 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>stdscr;</STRONG>
79 <EM>/*</EM> <EM>extensions</EM> <EM>*/</EM>
80 <STRONG>int</STRONG> <STRONG>ESCDELAY;</STRONG>
81 <STRONG>int</STRONG> <STRONG>TABSIZE;</STRONG>
82 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>newscr;</STRONG>
85 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
86 This page summarizes data types, constants, and variables provided by
87 the <EM>curses</EM> library. Locate further discussion in <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>.
89 Depending on <EM>ncurses</EM>'s build-time configuration, the variables may
90 instead be macros (see <STRONG><A HREF="curs_threads.3x.html">curs_threads(3x)</A></STRONG> and <STRONG><A HREF="curs_opaque.3x.html">curs_opaque(3x)</A></STRONG>) that
91 provide read-only access to the library's state. In either case,
92 applications should treat them as read-only to avoid confusing the
96 </PRE><H3><a name="h3-bool_-TRUE_-FALSE"><EM>bool,</EM> TRUE, FALSE</a></H3><PRE>
97 X/Open Issue 4 <EM>curses</EM> (1996) preceded the ISO C99 and ISO C++98
98 standards, each of which also defined a Boolean data type. The <EM>curses</EM>
99 library requires an integral type <EM>bool</EM> and constants <STRONG>TRUE</STRONG> and <STRONG>FALSE</STRONG> to
100 store its two possible values.
103 </PRE><H3><a name="h3-ERR_-OK">ERR, OK</a></H3><PRE>
104 <EM>curses</EM> and <EM>terminfo</EM> routines frequently return these constant integral
105 values indicating failure and success, respectively.
108 </PRE><H3><a name="h3-chtype"><EM>chtype</EM></a></H3><PRE>
109 The <EM>chtype</EM> integral type combines a ("narrow", 8-bit) character with
110 attributes encoding the character's <EM>rendition</EM>, such as the styling of
111 its typeface and/or foreground and background colors. See, for
112 example, <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">attron(3x)</A></STRONG>, and <STRONG><A HREF="curs_inch.3x.html">inch(3x)</A></STRONG>.
115 </PRE><H3><a name="h3-cchar_t_-attr_t"><EM>cchar_t,</EM> attr_t</a></H3><PRE>
116 <EM>chtype</EM> is too small for the standard C library's wide-character type,
117 <EM>wchar</EM><STRONG>_</STRONG><EM>t</EM>. <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> is a type that can accommodate an <EM>attr</EM><STRONG>_</STRONG><EM>t</EM> and enough
118 wide characters to store what Unicode terms a <EM>grapheme</EM> <EM>cluster</EM> (a
119 "user-perceived character" [UAX #29], which may nevertheless require
120 several character encoding units to represent). <EM>attr</EM><STRONG>_</STRONG><EM>t</EM> is an integral
121 type storing "wide" attributes that apply to <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM>s. See, for
122 example, <STRONG><A HREF="curs_add_wch.3x.html">add_wch(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">attr_on(3x)</A></STRONG>, and <STRONG><A HREF="curs_in_wch.3x.html">in_wch(3x)</A></STRONG>.
125 </PRE><H3><a name="h3-COLOR_PAIRS">COLOR_PAIRS</a></H3><PRE>
126 Once <EM>curses</EM> is initialized, <STRONG>COLOR_PAIRS</STRONG> contains the number of color
127 pairs supported by the terminal. Often, its value is the product
128 <STRONG>COLORS</STRONG> x <STRONG>COLORS</STRONG>, but this is not always true.
130 <STRONG>o</STRONG> A few terminals use HLS colors, ignoring this rule; and
132 <STRONG>o</STRONG> terminals supporting a large number of colors are limited by the
133 number of color pairs that a <EM>signed</EM> <EM>short</EM> value can represent.
136 </PRE><H3><a name="h3-COLORS">COLORS</a></H3><PRE>
137 Once <EM>curses</EM> is initialized, <STRONG>COLORS</STRONG> contains the number of colors
138 supported by the terminal.
141 </PRE><H3><a name="h3-COLS">COLS</a></H3><PRE>
142 Once <EM>curses</EM> is initialized, <STRONG>COLS</STRONG> contains the screen's width in
143 character cells; that is, the number of columns.
146 </PRE><H3><a name="h3-ESCDELAY">ESCDELAY</a></H3><PRE>
147 For <EM>curses</EM> to distinguish an escape character corresponding to a user's
148 press of an "Escape" key on the input device from one included in a
149 control sequence used by a cursor movement or function key, the library
150 waits to see if another key event occurs after the escape character.
151 <STRONG>ESCDELAY</STRONG> stores this interval in milliseconds.
154 </PRE><H3><a name="h3-LINES">LINES</a></H3><PRE>
155 Once <EM>curses</EM> is initialized, <STRONG>LINES</STRONG> contains the screen's height in
156 character cells; that is, the number of lines.
159 </PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
160 The <EM>curses</EM> library converts a tab character to this number of spaces as
161 it adds a tab to a window; see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>.
164 </PRE><H3><a name="h3-curscr">curscr</a></H3><PRE>
165 <EM>curses</EM> records updates to the terminal screen in a <EM>WINDOW</EM> structure
166 named <STRONG>curscr</STRONG>.
168 This object is referred to as the "physical screen" in <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>
169 and <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>.
172 </PRE><H3><a name="h3-newscr">newscr</a></H3><PRE>
173 <EM>ncurses</EM> collects pending updates to the terminal screen in a <EM>WINDOW</EM>
174 structure named <STRONG>newscr</STRONG>.
176 This object is referred to as the "virtual screen" in the
177 <STRONG><A HREF="curs_kernel.3x.html">curs_kernel(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, and <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>. When the
178 screen is refreshed, <EM>curses</EM> determines a minimal set of updates using
179 the terminal's capabilities to make <STRONG>curscr</STRONG> look like <STRONG>newscr</STRONG>.
182 </PRE><H3><a name="h3-stdscr">stdscr</a></H3><PRE>
183 Once <EM>curses</EM> is initialized, it creates a <EM>WINDOW</EM> structure named <STRONG>stdscr</STRONG>.
184 It is the same size as the terminal screen and is the default window
185 used by routines that do not take a parameter identifying one. Many
186 <EM>curses</EM> functions use this window.
189 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
190 Either <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG> or <STRONG><A HREF="curs_initscr.3x.html">newterm(3x)</A></STRONG> initializes <EM>curses</EM>.
192 If <EM>ncurses</EM> is configured to provide separate <EM>curses</EM> and <EM>terminfo</EM>
193 libraries, most of these variables reside in the <EM>curses</EM> library.
196 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
197 The X/Open Curses standard documents all of the foregoing types and
198 symbols except for <STRONG>newscr</STRONG>, <STRONG>TABSIZE</STRONG>, and <STRONG>ESCDELAY</STRONG>.
200 X/Open Curses describes <STRONG>curscr</STRONG> only as "an internal data structure";
201 SVID gave more details, noting its use "for certain low-level
202 operations like clearing and redrawing a screen containing garbage".
203 Neither specified its interaction with the rest of the interface beyond
204 use as an argument to <STRONG><A HREF="curs_outopts.3x.html">clearok(3x)</A></STRONG> and <STRONG><A HREF="curs_refresh.3x.html">wrefresh(3x)</A></STRONG>.
206 <STRONG>newscr</STRONG> is a feature of SVr4 <EM>curses</EM>. When refreshing the screen, this
207 window is used as a working area for combining the standard screen
208 <STRONG>stdscr</STRONG> with any other windows which the application may have created
209 with <STRONG><A HREF="curs_window.3x.html">newwin(3x)</A></STRONG>. When the updated <STRONG>newscr</STRONG> is complete, <EM>curses</EM> updates
210 <STRONG>curscr</STRONG> to match <STRONG>newscr</STRONG>.
212 <STRONG>TABSIZE</STRONG> is a feature of SVr4 <EM>curses</EM>.
214 <STRONG>o</STRONG> SVr4 initially sets <STRONG>TABSIZE</STRONG> from the terminal description's
215 <STRONG>init_tabs</STRONG> capability. After that, it can be altered by
216 applications using SVr4 <EM>curses</EM>.
218 <STRONG>o</STRONG> SVr4 <EM>curses</EM> uses the value of <STRONG>TABSIZE</STRONG> to compute the position of
219 tab stops when updating both the virtual screen with <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG> and
220 the physical screen with <STRONG><A HREF="curs_terminfo.3x.html">mvcur(3x)</A></STRONG>.
222 <STRONG>o</STRONG> <EM>ncurses</EM> uses the value of <STRONG>TABSIZE</STRONG> only to update the virtual
223 screen. It uses the terminal description's "<STRONG>it</STRONG>" (<STRONG>init_tabs</STRONG>)
224 capability for computing hardware tabs (that is, tab stops on the
227 <STRONG>o</STRONG> Other implementations differ. For instance, NetBSD <EM>curses</EM> allows
228 <STRONG>TABSIZE</STRONG> to be set through an environment variable. <EM>ncurses</EM> does
231 NetBSD <EM>curses</EM> does not support hardware tabs; it uses the <STRONG>init_tabs</STRONG>
232 capability and the <STRONG>TABSIZE</STRONG> variable only for updating the virtual
235 <STRONG>ESCDELAY</STRONG> is a feature of AIX <EM>curses</EM>.
237 <STRONG>o</STRONG> In AIX, the units for <STRONG>ESCDELAY</STRONG> are <EM>fifths</EM> of milliseconds.
239 <STRONG>o</STRONG> The default value for AIX's <STRONG>ESCDELAY</STRONG> equals 0.1 seconds.
241 <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for <STRONG>ESCDELAY</STRONG>; <EM>ncurses</EM>
242 does not enforce any upper limit.
244 <EM>ncurses</EM> has long used <STRONG>ESCDELAY</STRONG> with units of milliseconds, making it
245 impossible to be completely compatible with AIX. Consequently, most
246 users have decided either to override the value, or to rely upon its
250 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
251 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_opaque.3x.html">curs_opaque(3x)</A></STRONG>, <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG>, <STRONG><A HREF="curs_threads.3x.html">curs_threads(3x)</A></STRONG>,
252 <STRONG><A HREF="term_variables.3x.html">term_variables(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>
254 [UAX #29] "Unicode Standard Annex #29: Unicode Text Segmentation";
255 <https://unicode.org/reports/tr29/>
259 ncurses 6.4 2023-12-16 <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
263 <li><a href="#h2-NAME">NAME</a></li>
264 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
265 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
267 <li><a href="#h3-bool_-TRUE_-FALSE">bool, TRUE, FALSE</a></li>
268 <li><a href="#h3-ERR_-OK">ERR, OK</a></li>
269 <li><a href="#h3-chtype">chtype</a></li>
270 <li><a href="#h3-cchar_t_-attr_t">cchar_t, attr_t</a></li>
271 <li><a href="#h3-COLOR_PAIRS">COLOR_PAIRS</a></li>
272 <li><a href="#h3-COLORS">COLORS</a></li>
273 <li><a href="#h3-COLS">COLS</a></li>
274 <li><a href="#h3-ESCDELAY">ESCDELAY</a></li>
275 <li><a href="#h3-LINES">LINES</a></li>
276 <li><a href="#h3-TABSIZE">TABSIZE</a></li>
277 <li><a href="#h3-curscr">curscr</a></li>
278 <li><a href="#h3-newscr">newscr</a></li>
279 <li><a href="#h3-stdscr">stdscr</a></li>
282 <li><a href="#h2-NOTES">NOTES</a></li>
283 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
284 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>