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42 <H1 class="no-header">curs_variables 3x 2024-04-13 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>SCREEN</EM>, <EM>WINDOW</EM>, <STRONG>TRUE</STRONG>, <STRONG>FALSE</STRONG>, <STRONG>ERR</STRONG>, <STRONG>OK</STRONG>,
51 <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>,
52 <STRONG>TABSIZE</STRONG> - <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>SCREEN;</STRONG>
64 <STRONG>typedef</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>WINDOW;</STRONG>
66 <EM>/*</EM> <EM>constants</EM> <EM>*/</EM>
67 <STRONG>const</STRONG> <STRONG>bool</STRONG> <STRONG>TRUE;</STRONG>
68 <STRONG>const</STRONG> <STRONG>bool</STRONG> <STRONG>FALSE;</STRONG>
70 <STRONG>const</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>ERR;</STRONG>
71 <STRONG>const</STRONG> <EM>/*</EM> <STRONG>...</STRONG> <EM>*/</EM> <STRONG>OK;</STRONG>
73 <EM>/*</EM> <EM>variables</EM> <EM>*/</EM>
74 <STRONG>int</STRONG> <STRONG>COLORS;</STRONG>
75 <STRONG>int</STRONG> <STRONG>COLOR_PAIRS;</STRONG>
76 <STRONG>int</STRONG> <STRONG>COLS;</STRONG>
77 <STRONG>int</STRONG> <STRONG>LINES;</STRONG>
78 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>curscr;</STRONG>
79 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>stdscr;</STRONG>
81 <EM>/*</EM> <EM>extensions</EM> <EM>*/</EM>
82 <STRONG>int</STRONG> <STRONG>ESCDELAY;</STRONG>
83 <STRONG>int</STRONG> <STRONG>TABSIZE;</STRONG>
84 <STRONG>WINDOW</STRONG> <STRONG>*</STRONG> <STRONG>newscr;</STRONG>
87 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
88 This page summarizes data types, constants, and variables provided by
89 the <EM>curses</EM> library. Locate further discussion in <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>.
91 Depending on <EM>ncurses</EM>'s build-time configuration, the variables may
92 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
93 provide read-only access to the library's state. In either case,
94 applications should treat them as read-only to avoid confusing the
98 </PRE><H2><a name="h2-CONSTANTS">CONSTANTS</a></H2><PRE>
100 </PRE><H3><a name="h3-TRUE_FALSE">TRUE, FALSE</a></H3><PRE>
101 The <EM>curses</EM> library defines <STRONG>TRUE</STRONG> and <STRONG>FALSE</STRONG> to represent the values of
102 the Boolean data type.
105 </PRE><H3><a name="h3-ERR_OK">ERR, OK</a></H3><PRE>
106 <EM>curses</EM> and <EM>terminfo</EM> routines frequently return these constant integral
107 values indicating failure and success, respectively.
110 </PRE><H2><a name="h2-PREDEFINED-TYPES">PREDEFINED TYPES</a></H2><PRE>
112 </PRE><H3><a name="h3-bool"><EM>bool</EM></a></H3><PRE>
113 X/Open Issue 4 <EM>curses</EM> (1996) preceded the ISO C99 and ISO C++98
114 standards, each of which also defined a Boolean data type. The <EM>curses</EM>
115 library requires an integral type <EM>bool</EM>.
117 <STRONG>ncurses</STRONG>' configure script attempts to discover the data type used by
118 the system's C and C++ compilers, to reuse for the <EM>curses</EM> <EM>bool</EM>.
121 </PRE><H3><a name="h3-chtype"><EM>chtype</EM></a></H3><PRE>
122 The <EM>chtype</EM> integral type combines a ("narrow", 8-bit) character with
123 attributes encoding the character's <EM>rendition</EM>, such as the styling of
124 its typeface and/or foreground and background colors. See, for
125 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>.
128 </PRE><H3><a name="h3-cchar_t_attr_t"><EM>cchar_t,</EM> attr_t</a></H3><PRE>
129 <EM>chtype</EM> is too small for the standard C library's wide-character type,
130 <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
131 wide characters to store what Unicode terms a <EM>grapheme</EM> <EM>cluster</EM> (a
132 "user-perceived character" [UAX #29], which may nevertheless require
133 several character encoding units to represent). <EM>attr</EM><STRONG>_</STRONG><EM>t</EM> is an integral
134 type storing "wide" attributes that apply to <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM>s. See, for
135 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>.
138 </PRE><H3><a name="h3-SCREEN"><EM>SCREEN</EM></a></H3><PRE>
139 <EM>curses</EM> manages a terminal device with this structure type; see
140 <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG>.
143 </PRE><H3><a name="h3-WINDOW"><EM>WINDOW</EM></a></H3><PRE>
144 <EM>curses</EM> represents rectangular portions of the terminal screen with the
145 <EM>WINDOW</EM> structure type; see subsection "Overview" of <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>.
148 </PRE><H2><a name="h2-VARIABLES">VARIABLES</a></H2><PRE>
150 </PRE><H3><a name="h3-curscr_stdscr_newscr">curscr, stdscr, newscr</a></H3><PRE>
151 The library records updates to the terminal screen in a window named
152 <STRONG>curscr</STRONG>. This object is referred to as the "physical screen" in
153 <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>.
155 <EM>ncurses</EM> collects pending updates to the terminal screen in a window
156 named <STRONG>newscr</STRONG>. This object is referred to as the "virtual screen" in
157 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
158 screen is refreshed, <EM>curses</EM> determines a minimal set of updates using
159 the terminal's capabilities to make <STRONG>curscr</STRONG> look like <STRONG>newscr</STRONG>.
161 Once <EM>curses</EM> is initialized, it creates a window named <STRONG>stdscr</STRONG>. It is
162 the same size as the terminal screen and is the default window used by
163 routines that do not take a parameter identifying one. Many <EM>curses</EM>
164 functions use this window.
167 </PRE><H3><a name="h3-COLORS">COLORS</a></H3><PRE>
168 Once <EM>curses</EM> is initialized, <STRONG>COLORS</STRONG> contains the number of colors
169 supported by the terminal; see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>.
172 </PRE><H3><a name="h3-COLOR_PAIRS">COLOR_PAIRS</a></H3><PRE>
173 Once <EM>curses</EM> is initialized, <STRONG>COLOR_PAIRS</STRONG> contains the number of color
174 pairs supported by the terminal; see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>.
177 </PRE><H3><a name="h3-COLS_LINES">COLS, LINES</a></H3><PRE>
178 Once <EM>curses</EM> is initialized, <STRONG>COLS</STRONG> and <STRONG>LINES</STRONG> contain the screen's width
179 and height in character cells, respectively; that is, the number of
183 </PRE><H3><a name="h3-ESCDELAY">ESCDELAY</a></H3><PRE>
184 For <EM>curses</EM> to distinguish the ESC character resulting from a user's
185 press of the "Escape" key on the input device from one beginning an
186 <EM>escape</EM> <EM>sequence</EM> (as commonly produced by function keys), it waits after
187 the escape character to see if further characters are available on the
188 input stream within a short interval. <STRONG>ESCDELAY</STRONG> stores this interval in
191 If <STRONG><A HREF="curs_inopts.3x.html">keypad(3x)</A></STRONG> is disabled for the <EM>curses</EM> window receiving input, a
192 program must disambiguate escape sequences itself.
195 </PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
196 The <EM>curses</EM> library converts a tab character to this number of spaces as
197 it adds a tab to a window; see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>.
200 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
201 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>.
203 If <EM>ncurses</EM> is configured to provide separate <EM>curses</EM> and <EM>tinfo</EM>
204 libraries, most of these variables reside in the former.
207 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
208 The X/Open Curses standard documents all of the foregoing types and
209 symbols except for <STRONG>newscr</STRONG>, <STRONG>TABSIZE</STRONG>, and <STRONG>ESCDELAY</STRONG>.
211 X/Open Curses describes <STRONG>curscr</STRONG> only as "an internal data structure";
212 SVr4 gave more details, noting its use "for certain low-level
213 operations like clearing and redrawing a screen containing garbage".
214 Neither specified its interaction with the rest of the interface beyond
215 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>.
217 <STRONG>newscr</STRONG> is a feature of SVr4 <EM>curses</EM>. When refreshing the screen, it is
218 used as a working area for combining the standard window <STRONG>stdscr</STRONG> with
219 any others the application may have created with <STRONG><A HREF="curs_window.3x.html">newwin(3x)</A></STRONG>. When the
220 update of <STRONG>newscr</STRONG> is complete, <EM>curses</EM> modifies <STRONG>curscr</STRONG> to match <STRONG>newscr</STRONG>.
222 <STRONG>TABSIZE</STRONG> is a feature of SVr4 <EM>curses</EM>.
224 <STRONG>o</STRONG> SVr4 initially sets <STRONG>TABSIZE</STRONG> from the terminal description's
225 <STRONG>init_tabs</STRONG> capability. After that, it can be altered by
226 applications using SVr4 <EM>curses</EM>.
228 <STRONG>o</STRONG> SVr4 <EM>curses</EM> uses the value of <STRONG>TABSIZE</STRONG> to compute the position of
229 tab stops when updating both the virtual screen with <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG> and
230 the physical screen with <STRONG><A HREF="curs_terminfo.3x.html">mvcur(3x)</A></STRONG>.
232 <STRONG>o</STRONG> <EM>ncurses</EM> uses the value of <STRONG>TABSIZE</STRONG> only to update the virtual
233 screen. It uses the terminal description's "<STRONG>it</STRONG>" (<STRONG>init_tabs</STRONG>)
234 capability for computing hardware tabs (that is, tab stops on the
237 <STRONG>o</STRONG> Other implementations differ. For instance, NetBSD <EM>curses</EM> allows
238 <STRONG>TABSIZE</STRONG> to be set through an environment variable. <EM>ncurses</EM> does
241 NetBSD <EM>curses</EM> does not support hardware tabs; it uses the <STRONG>init_tabs</STRONG>
242 capability and the <STRONG>TABSIZE</STRONG> variable only for updating the virtual
245 <STRONG>ESCDELAY</STRONG> is a feature of AIX <EM>curses</EM>.
247 <STRONG>o</STRONG> In AIX, the units for <STRONG>ESCDELAY</STRONG> are <EM>fifths</EM> of milliseconds.
249 <STRONG>o</STRONG> The default value for AIX's <STRONG>ESCDELAY</STRONG> equals 0.1 seconds.
251 <STRONG>o</STRONG> AIX also enforces a limit of 10,000 seconds for <STRONG>ESCDELAY</STRONG>; <EM>ncurses</EM>
252 does not enforce any upper limit.
254 <EM>ncurses</EM> has long used <STRONG>ESCDELAY</STRONG> with units of milliseconds, making it
255 impossible to be completely compatible with AIX. Consequently, most
256 users have decided either to override the value, or to rely upon its
260 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
261 <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>,
262 <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>
264 [UAX #29] "Unicode Standard Annex #29: Unicode Text Segmentation";
265 <https://unicode.org/reports/tr29/>
269 ncurses 6.4 2024-04-13 <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>
273 <li><a href="#h2-NAME">NAME</a></li>
274 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
275 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
276 <li><a href="#h2-CONSTANTS">CONSTANTS</a>
278 <li><a href="#h3-TRUE_FALSE">TRUE, FALSE</a></li>
279 <li><a href="#h3-ERR_OK">ERR, OK</a></li>
282 <li><a href="#h2-PREDEFINED-TYPES">PREDEFINED TYPES</a>
284 <li><a href="#h3-bool">bool</a></li>
285 <li><a href="#h3-chtype">chtype</a></li>
286 <li><a href="#h3-cchar_t_attr_t">cchar_t, attr_t</a></li>
287 <li><a href="#h3-SCREEN">SCREEN</a></li>
288 <li><a href="#h3-WINDOW">WINDOW</a></li>
291 <li><a href="#h2-VARIABLES">VARIABLES</a>
293 <li><a href="#h3-curscr_stdscr_newscr">curscr, stdscr, newscr</a></li>
294 <li><a href="#h3-COLORS">COLORS</a></li>
295 <li><a href="#h3-COLOR_PAIRS">COLOR_PAIRS</a></li>
296 <li><a href="#h3-COLS_LINES">COLS, LINES</a></li>
297 <li><a href="#h3-ESCDELAY">ESCDELAY</a></li>
298 <li><a href="#h3-TABSIZE">TABSIZE</a></li>
301 <li><a href="#h2-NOTES">NOTES</a></li>
302 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
303 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>