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31 * SVID 4, Volume 3, p. 408
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38 <TITLE>curs_variables 3x 2024-01-05 ncurses 6.4 Library calls</TITLE>
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43 <H1 class="no-header">curs_variables 3x 2024-01-05 ncurses 6.4 Library calls</H1>
45 <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>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <EM>bool</EM>, <EM>chtype</EM>, <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM>, <EM>attr</EM><STRONG>_</STRONG><EM>t</EM>, <EM>SCREEN</EM>, <EM>WINDOW</EM>, <STRONG>TRUE</STRONG>, <STRONG>FALSE</STRONG>, <STRONG>ERR</STRONG>, <STRONG>OK</STRONG>,
52 <STRONG>curscr</STRONG>, <STRONG>newscr</STRONG>, <STRONG>stdscr</STRONG>, <STRONG>COLORS</STRONG>, <STRONG>COLOR_PAIRS</STRONG>, <STRONG>COLS</STRONG>, <STRONG>LINES</STRONG>, <STRONG>ESCDELAY</STRONG>,
53 <STRONG>TABSIZE</STRONG> - <EM>curses</EM> data types, constants, and global variables
56 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
57 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
59 <EM>/*</EM> <EM>data</EM> <EM>types</EM> <EM>*/</EM>
60 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>bool;</STRONG>
61 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>chtype;</STRONG>
62 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>cchar_t;</STRONG>
63 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>attr_t;</STRONG>
64 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>SCREEN;</STRONG>
65 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>WINDOW;</STRONG>
67 <EM>/*</EM> <EM>constants</EM> <EM>*/</EM>
68 <STRONG>const</STRONG> <STRONG>bool</STRONG> <STRONG>TRUE;</STRONG>
69 <STRONG>const</STRONG> <STRONG>bool</STRONG> <STRONG>FALSE;</STRONG>
71 <STRONG>const</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>ERR;</STRONG>
72 <STRONG>const</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>OK;</STRONG>
74 <EM>/*</EM> <EM>variables</EM> <EM>*/</EM>
75 <STRONG>int</STRONG> <STRONG>COLORS;</STRONG>
76 <STRONG>int</STRONG> <STRONG>COLOR_PAIRS;</STRONG>
77 <STRONG>int</STRONG> <STRONG>COLS;</STRONG>
78 <STRONG>int</STRONG> <STRONG>LINES;</STRONG>
79 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>curscr;</STRONG>
80 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>stdscr;</STRONG>
82 <EM>/*</EM> <EM>extensions</EM> <EM>*/</EM>
83 <STRONG>int</STRONG> <STRONG>ESCDELAY;</STRONG>
84 <STRONG>int</STRONG> <STRONG>TABSIZE;</STRONG>
85 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>newscr;</STRONG>
88 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
89 This page summarizes data types, constants, and variables provided by
90 the <EM>curses</EM> library. Locate further discussion in <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>.
92 Depending on <EM>ncurses</EM>'s build-time configuration, the variables may
93 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
94 provide read-only access to the library's state. In either case,
95 applications should treat them as read-only to avoid confusing the
99 </PRE><H2><a name="h2-CONSTANTS">CONSTANTS</a></H2><PRE>
101 </PRE><H3><a name="h3-TRUE_FALSE">TRUE, FALSE</a></H3><PRE>
102 The <EM>curses</EM> library defines <STRONG>TRUE</STRONG> and <STRONG>FALSE</STRONG> to represent the values of
103 the Boolean data type.
106 </PRE><H3><a name="h3-ERR_OK">ERR, OK</a></H3><PRE>
107 <EM>curses</EM> and <EM>terminfo</EM> routines frequently return these constant integral
108 values indicating failure and success, respectively.
111 </PRE><H2><a name="h2-PREDEFINED-TYPES">PREDEFINED TYPES</a></H2><PRE>
113 </PRE><H3><a name="h3-bool"><EM>bool</EM></a></H3><PRE>
114 X/Open Issue 4 <EM>curses</EM> (1996) preceded the ISO C99 and ISO C++98
115 standards, each of which also defined a Boolean data type. The <EM>curses</EM>
116 library requires an integral type <EM>bool</EM>.
118 <STRONG>ncurses</STRONG>' configure script attempts to discover the data type used by
119 the system's C and C++ compilers, to reuse for the <EM>curses</EM> <EM>bool</EM>.
122 </PRE><H3><a name="h3-chtype"><EM>chtype</EM></a></H3><PRE>
123 The <EM>chtype</EM> integral type combines a ("narrow", 8-bit) character with
124 attributes encoding the character's <EM>rendition</EM>, such as the styling of
125 its typeface and/or foreground and background colors. See, for
126 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>.
129 </PRE><H3><a name="h3-cchar_t_attr_t"><EM>cchar_t,</EM> attr_t</a></H3><PRE>
130 <EM>chtype</EM> is too small for the standard C library's wide-character type,
131 <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
132 wide characters to store what Unicode terms a <EM>grapheme</EM> <EM>cluster</EM> (a
133 "user-perceived character" [UAX #29], which may nevertheless require
134 several character encoding units to represent). <EM>attr</EM><STRONG>_</STRONG><EM>t</EM> is an integral
135 type storing "wide" attributes that apply to <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM>s. See, for
136 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>.
139 </PRE><H3><a name="h3-SCREEN"><EM>SCREEN</EM></a></H3><PRE>
140 <EM>curses</EM> manages a terminal device with this structure type; see
141 <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG>.
144 </PRE><H3><a name="h3-WINDOW"><EM>WINDOW</EM></a></H3><PRE>
145 <EM>curses</EM> represents rectangular portions of the terminal screen with the
146 <EM>WINDOW</EM> structure type; see subsection "Overview" of <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>.
149 </PRE><H2><a name="h2-VARIABLES">VARIABLES</a></H2><PRE>
151 </PRE><H3><a name="h3-curscr_stdscr_newscr">curscr, stdscr, newscr</a></H3><PRE>
152 The library records updates to the terminal screen in a window named
153 <STRONG>curscr</STRONG>. This object is referred to as the "physical screen" in
154 <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>.
156 <EM>ncurses</EM> collects pending updates to the terminal screen in a window
157 named <STRONG>newscr</STRONG>. This object is referred to as the "virtual screen" in
158 the <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
159 screen is refreshed, <EM>curses</EM> determines a minimal set of updates using
160 the terminal's capabilities to make <STRONG>curscr</STRONG> look like <STRONG>newscr</STRONG>.
162 Once <EM>curses</EM> is initialized, it creates a window named <STRONG>stdscr</STRONG>. It is
163 the same size as the terminal screen and is the default window used by
164 routines that do not take a parameter identifying one. Many <EM>curses</EM>
165 functions use this window.
168 </PRE><H3><a name="h3-COLORS">COLORS</a></H3><PRE>
169 Once <EM>curses</EM> is initialized, <STRONG>COLORS</STRONG> contains the number of colors
170 supported by the terminal; see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>.
173 </PRE><H3><a name="h3-COLOR_PAIRS">COLOR_PAIRS</a></H3><PRE>
174 Once <EM>curses</EM> is initialized, <STRONG>COLOR_PAIRS</STRONG> contains the number of color
175 pairs supported by the terminal; see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>.
178 </PRE><H3><a name="h3-COLS_LINES">COLS, LINES</a></H3><PRE>
179 Once <EM>curses</EM> is initialized, <STRONG>COLS</STRONG> and <STRONG>LINES</STRONG> contain the screen's width
180 and height in character cells, respectively; that is, the number of
184 </PRE><H3><a name="h3-ESCDELAY">ESCDELAY</a></H3><PRE>
185 For <EM>curses</EM> to distinguish an escape character corresponding to a user's
186 press of an "Escape" key on the input device from one included in a
187 control sequence used by a cursor movement or function key, the library
188 waits to see if another key event occurs after the escape character.
189 <STRONG>ESCDELAY</STRONG> stores this interval in milliseconds.
192 </PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
193 The <EM>curses</EM> library converts a tab character to this number of spaces as
194 it adds a tab to a window; see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>.
197 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
198 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>.
200 If <EM>ncurses</EM> is configured to provide separate <EM>curses</EM> and <EM>terminfo</EM>
201 libraries, most of these variables reside in the <EM>curses</EM> library.
204 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
205 The X/Open Curses standard documents all of the foregoing types and
206 symbols except for <STRONG>newscr</STRONG>, <STRONG>TABSIZE</STRONG>, and <STRONG>ESCDELAY</STRONG>.
208 X/Open Curses describes <STRONG>curscr</STRONG> only as "an internal data structure";
209 SVr4 gave more details, noting its use "for certain low-level
210 operations like clearing and redrawing a screen containing garbage".
211 Neither specified its interaction with the rest of the interface beyond
212 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>.
214 <STRONG>newscr</STRONG> is a feature of SVr4 <EM>curses</EM>. When refreshing the screen, it is
215 used as a working area for combining the standard window <STRONG>stdscr</STRONG> with
216 any others the application may have created with <STRONG><A HREF="curs_window.3x.html">newwin(3x)</A></STRONG>. When the
217 update of <STRONG>newscr</STRONG> is complete, <EM>curses</EM> modifies <STRONG>curscr</STRONG> to match <STRONG>newscr</STRONG>.
219 <STRONG>TABSIZE</STRONG> is a feature of SVr4 <EM>curses</EM>.
221 <STRONG>o</STRONG> SVr4 initially sets <STRONG>TABSIZE</STRONG> from the terminal description's
222 <STRONG>init_tabs</STRONG> capability. After that, it can be altered by
223 applications using SVr4 <EM>curses</EM>.
225 <STRONG>o</STRONG> SVr4 <EM>curses</EM> uses the value of <STRONG>TABSIZE</STRONG> to compute the position of
226 tab stops when updating both the virtual screen with <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG> and
227 the physical screen with <STRONG><A HREF="curs_terminfo.3x.html">mvcur(3x)</A></STRONG>.
229 <STRONG>o</STRONG> <EM>ncurses</EM> uses the value of <STRONG>TABSIZE</STRONG> only to update the virtual
230 screen. It uses the terminal description's "<STRONG>it</STRONG>" (<STRONG>init_tabs</STRONG>)
231 capability for computing hardware tabs (that is, tab stops on the
234 <STRONG>o</STRONG> Other implementations differ. For instance, NetBSD <EM>curses</EM> allows
235 <STRONG>TABSIZE</STRONG> to be set through an environment variable. <EM>ncurses</EM> does
238 NetBSD <EM>curses</EM> does not support hardware tabs; it uses the <STRONG>init_tabs</STRONG>
239 capability and the <STRONG>TABSIZE</STRONG> variable only for updating the virtual
242 <STRONG>ESCDELAY</STRONG> is a feature of AIX <EM>curses</EM>.
244 <STRONG>o</STRONG> In AIX, the units for <STRONG>ESCDELAY</STRONG> are <EM>fifths</EM> of milliseconds.
246 <STRONG>o</STRONG> The default value for AIX's <STRONG>ESCDELAY</STRONG> equals 0.1 seconds.
248 <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for <STRONG>ESCDELAY</STRONG>; <EM>ncurses</EM>
249 does not enforce any upper limit.
251 <EM>ncurses</EM> has long used <STRONG>ESCDELAY</STRONG> with units of milliseconds, making it
252 impossible to be completely compatible with AIX. Consequently, most
253 users have decided either to override the value, or to rely upon its
257 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
258 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_color.3x.html">curs_color(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>,
259 <STRONG><A HREF="curs_threads.3x.html">curs_threads(3x)</A></STRONG>, <STRONG><A HREF="term_variables.3x.html">term_variables(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>
261 [UAX #29] "Unicode Standard Annex #29: Unicode Text Segmentation";
262 <https://unicode.org/reports/tr29/>
266 ncurses 6.4 2024-01-05 <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
270 <li><a href="#h2-NAME">NAME</a></li>
271 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
272 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
273 <li><a href="#h2-CONSTANTS">CONSTANTS</a>
275 <li><a href="#h3-TRUE_FALSE">TRUE, FALSE</a></li>
276 <li><a href="#h3-ERR_OK">ERR, OK</a></li>
279 <li><a href="#h2-PREDEFINED-TYPES">PREDEFINED TYPES</a>
281 <li><a href="#h3-bool">bool</a></li>
282 <li><a href="#h3-chtype">chtype</a></li>
283 <li><a href="#h3-cchar_t_attr_t">cchar_t, attr_t</a></li>
284 <li><a href="#h3-SCREEN">SCREEN</a></li>
285 <li><a href="#h3-WINDOW">WINDOW</a></li>
288 <li><a href="#h2-VARIABLES">VARIABLES</a>
290 <li><a href="#h3-curscr_stdscr_newscr">curscr, stdscr, newscr</a></li>
291 <li><a href="#h3-COLORS">COLORS</a></li>
292 <li><a href="#h3-COLOR_PAIRS">COLOR_PAIRS</a></li>
293 <li><a href="#h3-COLS_LINES">COLS, LINES</a></li>
294 <li><a href="#h3-ESCDELAY">ESCDELAY</a></li>
295 <li><a href="#h3-TABSIZE">TABSIZE</a></li>
298 <li><a href="#h2-NOTES">NOTES</a></li>
299 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
300 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>