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30 * @Id: curs_variables.3x,v 1.34 2023/11/25 14:32:36 tom Exp @
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42 <H1 class="no-header">curs_variables 3x 2023-11-25 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>ESCDELAY;</STRONG>
77 <STRONG>int</STRONG> <STRONG>LINES;</STRONG>
78 <STRONG>int</STRONG> <STRONG>TABSIZE;</STRONG>
79 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>curscr;</STRONG>
80 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>newscr;</STRONG>
81 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>stdscr;</STRONG>
84 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
85 This page summarizes data types, constants, and variables provided by
86 the <EM>curses</EM> library. Locate further discussion in <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>.
88 Depending on <EM>ncurses</EM>'s build-time configuration, the variables may
89 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
90 provide read-only access to the library's state. In either case,
91 applications should treat them as read-only to avoid confusing the
95 </PRE><H3><a name="h3-bool_-TRUE_-FALSE">bool, TRUE, FALSE</a></H3><PRE>
96 X/Open Issue 4 <EM>curses</EM> (1996) preceded the ISO C99 and ISO C++98
97 standards, each of which also defined a Boolean data type. The <EM>curses</EM>
98 library requires an integral type <EM>bool</EM> and constants <STRONG>TRUE</STRONG> and <STRONG>FALSE</STRONG> to
99 store its two possible values.
102 </PRE><H3><a name="h3-ERR_-OK">ERR, OK</a></H3><PRE>
103 <EM>curses</EM> and <EM>terminfo</EM> routines frequently return these constant integral
104 values indicating failure and success, respectively.
107 </PRE><H3><a name="h3-chtype">chtype</a></H3><PRE>
108 The <EM>chtype</EM> integral type combines a ("narrow", 8-bit) character with
109 attributes encoding the character's <EM>rendition</EM>, such as the styling of
110 its typeface and/or foreground and background colors. See, for
111 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>.
114 </PRE><H3><a name="h3-cchar_t_-attr_t">cchar_t, attr_t</a></H3><PRE>
115 <EM>chtype</EM> is too small for the standard C library's wide-character type,
116 <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
117 wide characters to store what Unicode terms a <EM>grapheme</EM> <EM>cluster</EM> (a
118 "user-perceived character" [UAX #29], which may nevertheless require
119 several character encoding units to represent). <EM>attr</EM><STRONG>_</STRONG><EM>t</EM> is an integral
120 type storing "wide" attributes that apply to <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM>s. See, for
121 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>.
124 </PRE><H3><a name="h3-COLOR_PAIRS">COLOR_PAIRS</a></H3><PRE>
125 Once <EM>curses</EM> is initialized, <STRONG>COLOR_PAIRS</STRONG> contains the number of color
126 pairs supported by the terminal. Often, its value is the product
127 <STRONG>COLORS</STRONG> x <STRONG>COLORS</STRONG>, but this is not always true.
129 <STRONG>o</STRONG> A few terminals use HLS colors, ignoring this rule; and
131 <STRONG>o</STRONG> terminals supporting a large number of colors are limited by the
132 number of color pairs that a <EM>signed</EM> <EM>short</EM> value can represent.
135 </PRE><H3><a name="h3-COLORS">COLORS</a></H3><PRE>
136 Once <EM>curses</EM> is initialized, <STRONG>COLORS</STRONG> contains the number of colors
137 supported by the terminal.
140 </PRE><H3><a name="h3-COLS">COLS</a></H3><PRE>
141 Once <EM>curses</EM> is initialized, <STRONG>COLS</STRONG> contains the screen's width in
142 character cells; that is, the number of columns.
145 </PRE><H3><a name="h3-ESCDELAY">ESCDELAY</a></H3><PRE>
146 For <EM>curses</EM> to distinguish an escape character corresponding to a user's
147 press of an "Escape" key on the input device from one included in a
148 control sequence used by a cursor movement or function key, the library
149 waits to see if another key event occurs after the escape character.
150 <STRONG>ESCDELAY</STRONG> stores this interval in milliseconds.
153 </PRE><H3><a name="h3-LINES">LINES</a></H3><PRE>
154 Once <EM>curses</EM> is initialized, <STRONG>LINES</STRONG> contains the screen's height in
155 character cells; that is, the number of lines.
158 </PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
159 The <EM>curses</EM> library converts a tab character to this number of spaces as
160 it adds a tab to a window; see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>.
163 </PRE><H3><a name="h3-curscr">curscr</a></H3><PRE>
164 <EM>curses</EM> records updates to the terminal screen in a <EM>WINDOW</EM> structure
165 named <STRONG>curscr</STRONG>.
167 This object is referred to as the "physical screen" in <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>
168 and <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>.
171 </PRE><H3><a name="h3-newscr">newscr</a></H3><PRE>
172 <EM>ncurses</EM> collects pending updates to the terminal screen in a <EM>WINDOW</EM>
173 structure named <STRONG>newscr</STRONG>.
175 This object is referred to as the "virtual screen" in the
176 <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
177 screen is refreshed, <EM>curses</EM> determines a minimal set of updates using
178 the terminal's capabilities to make <STRONG>curscr</STRONG> look like <STRONG>newscr</STRONG>.
181 </PRE><H3><a name="h3-stdscr">stdscr</a></H3><PRE>
182 Once <EM>curses</EM> is initialized, it creates a <EM>WINDOW</EM> structure named <STRONG>stdscr</STRONG>.
183 It is the same size as the terminal screen and is the default window
184 used by routines that do not take a parameter identifying one. Many
185 <EM>curses</EM> functions use this window.
188 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
189 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>.
191 If <EM>ncurses</EM> is configured to provide separate <EM>curses</EM> and <EM>terminfo</EM>
192 libraries, most of these variables reside in the <EM>curses</EM> library.
195 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
196 The X/Open Curses standard documents all of the foregoing types and
197 symbols except for <STRONG>newscr</STRONG>, <STRONG>TABSIZE</STRONG>, and <STRONG>ESCDELAY</STRONG>.
199 X/Open Curses describes <STRONG>curscr</STRONG> only as "an internal data structure";
200 SVID gave more details, noting its use "for certain low-level
201 operations like clearing and redrawing a screen containing garbage".
202 Neither specified its interaction with the rest of the interface beyond
203 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>.
205 <STRONG>newscr</STRONG> is a feature of SVr4 <EM>curses</EM>. When refreshing the screen, this
206 window is used as a working area for combining the standard screen
207 <STRONG>stdscr</STRONG> with any other windows which the application may have created
208 with <STRONG><A HREF="curs_window.3x.html">newwin(3x)</A></STRONG>. When the updated <STRONG>newscr</STRONG> is complete, <EM>curses</EM> updates
209 <STRONG>curscr</STRONG> to match <STRONG>newscr</STRONG>.
211 <STRONG>TABSIZE</STRONG> is a feature of SVr4 <EM>curses</EM>.
213 <STRONG>o</STRONG> SVr4 initially sets <STRONG>TABSIZE</STRONG> from the terminal description's
214 <STRONG>init_tabs</STRONG> capability. After that, it can be altered by
215 applications using SVr4 <EM>curses</EM>.
217 <STRONG>o</STRONG> SVr4 <EM>curses</EM> uses the value of <STRONG>TABSIZE</STRONG> to compute the position of
218 tab stops when updating both the virtual screen with <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG> and
219 the physical screen with <STRONG><A HREF="curs_terminfo.3x.html">mvcur(3x)</A></STRONG>.
221 <STRONG>o</STRONG> <EM>ncurses</EM> uses the value of <STRONG>TABSIZE</STRONG> only to update the virtual
222 screen. It uses the terminal description's "<STRONG>it</STRONG>" (<STRONG>init_tabs</STRONG>)
223 capability for computing hardware tabs (that is, tab stops on the
226 <STRONG>o</STRONG> Other implementations differ. For instance, NetBSD <EM>curses</EM> allows
227 <STRONG>TABSIZE</STRONG> to be set through an environment variable. <EM>ncurses</EM> does
230 NetBSD <EM>curses</EM> does not support hardware tabs; it uses the <STRONG>init_tabs</STRONG>
231 capability and the <STRONG>TABSIZE</STRONG> variable only for updating the virtual
234 <STRONG>ESCDELAY</STRONG> is a feature of AIX <EM>curses</EM>.
236 <STRONG>o</STRONG> In AIX, the units for <STRONG>ESCDELAY</STRONG> are <EM>fifths</EM> of milliseconds.
238 <STRONG>o</STRONG> The default value for AIX's <STRONG>ESCDELAY</STRONG> equals 0.1 seconds.
240 <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for <STRONG>ESCDELAY</STRONG>; <EM>ncurses</EM>
241 does not enforce any upper limit.
243 <EM>ncurses</EM> has long used <STRONG>ESCDELAY</STRONG> with units of milliseconds, making it
244 impossible to be completely compatible with AIX. Consequently, most
245 users have decided either to override the value, or to rely upon its
249 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
250 <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>,
251 <STRONG><A HREF="term_variables.3x.html">term_variables(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>
253 [UAX #29] "Unicode Standard Annex #29: Unicode Text Segmentation";
254 <https://unicode.org/reports/tr29/>
258 ncurses 6.4 2023-11-25 <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
262 <li><a href="#h2-NAME">NAME</a></li>
263 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
264 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
266 <li><a href="#h3-bool_-TRUE_-FALSE">bool, TRUE, FALSE</a></li>
267 <li><a href="#h3-ERR_-OK">ERR, OK</a></li>
268 <li><a href="#h3-chtype">chtype</a></li>
269 <li><a href="#h3-cchar_t_-attr_t">cchar_t, attr_t</a></li>
270 <li><a href="#h3-COLOR_PAIRS">COLOR_PAIRS</a></li>
271 <li><a href="#h3-COLORS">COLORS</a></li>
272 <li><a href="#h3-COLS">COLS</a></li>
273 <li><a href="#h3-ESCDELAY">ESCDELAY</a></li>
274 <li><a href="#h3-LINES">LINES</a></li>
275 <li><a href="#h3-TABSIZE">TABSIZE</a></li>
276 <li><a href="#h3-curscr">curscr</a></li>
277 <li><a href="#h3-newscr">newscr</a></li>
278 <li><a href="#h3-stdscr">stdscr</a></li>
281 <li><a href="#h2-NOTES">NOTES</a></li>
282 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
283 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>