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43 <H1 class="no-header">curs_addch 3x 2023-09-30 ncurses 6.4 Library calls</H1>
45 <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>addch</STRONG>, <STRONG>waddch</STRONG>, <STRONG>mvaddch</STRONG>, <STRONG>mvwaddch</STRONG>, <STRONG>echochar</STRONG>, <STRONG>wechochar</STRONG> - add a <EM>curses</EM>
52 character to a window and advance the cursor
55 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
56 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
58 <STRONG>int</STRONG> <STRONG>addch(const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
59 <STRONG>int</STRONG> <STRONG>waddch(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
60 <STRONG>int</STRONG> <STRONG>mvaddch(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
61 <STRONG>int</STRONG> <STRONG>mvwaddch(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
63 <STRONG>int</STRONG> <STRONG>echochar(const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
64 <STRONG>int</STRONG> <STRONG>wechochar(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
67 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
69 </PRE><H3><a name="h3-Adding-characters">Adding characters</a></H3><PRE>
70 The <STRONG>addch</STRONG>, <STRONG>waddch</STRONG>, <STRONG>mvaddch</STRONG> and <STRONG>mvwaddch</STRONG> routines put the character <EM>ch</EM>
71 into the given window at its current window position, which is then
72 advanced. They are analogous to <STRONG>putchar(3)</STRONG> in <STRONG>stdio(3)</STRONG>. If the
73 advance is at the right margin:
75 <STRONG>o</STRONG> The cursor automatically wraps to the beginning of the next line.
77 <STRONG>o</STRONG> At the bottom of the current scrolling region, and if <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG>
78 is enabled, the scrolling region is scrolled up one line.
80 <STRONG>o</STRONG> If <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is not enabled, writing a character at the lower
81 right margin succeeds. However, an error is returned because it is
82 not possible to wrap to a new line
84 If <EM>ch</EM> is a tab, newline, carriage return or backspace, the cursor is
85 moved appropriately within the window:
87 <STRONG>o</STRONG> Backspace moves the cursor one character left; at the left edge of
88 a window it does nothing.
90 <STRONG>o</STRONG> Carriage return moves the cursor to the window left margin on the
93 <STRONG>o</STRONG> Newline does a <STRONG>clrtoeol</STRONG>, then moves the cursor to the window left
94 margin on the next line, scrolling the window if on the last line.
96 <STRONG>o</STRONG> Tabs are considered to be at every eighth column. The tab interval
97 may be altered by setting the <STRONG>TABSIZE</STRONG> variable.
99 If <EM>ch</EM> is any other nonprintable character, it is drawn in printable
100 form, using the same convention as <STRONG><A HREF="unctrl.3x.html">unctrl(3x)</A></STRONG>:
102 <STRONG>o</STRONG> Control characters are displayed in the <STRONG>^</STRONG><EM>X</EM> notation.
104 <STRONG>o</STRONG> Values above 128 are either meta characters (if the screen has not
105 been initialized, or if <STRONG><A HREF="curs_inopts.3x.html">meta(3x)</A></STRONG> has been called with a <STRONG>TRUE</STRONG> E
106 parameter), shown in the <STRONG>M-</STRONG><EM>X</EM> notation, or are displayed as
107 themselves. In the latter case, the values may not be printable;
108 this follows the X/Open specification.
110 Calling <STRONG>winch</STRONG> after adding a nonprintable character does not return the
111 character itself, but instead returns the printable representation of
114 Video attributes can be combined with a character argument passed to
115 <STRONG>addch</STRONG> or related functions by logical-ORing them into the character.
116 (Thus, text, including attributes, can be copied from one place to
117 another using <STRONG><A HREF="curs_inch.3x.html">inch(3x)</A></STRONG> and <STRONG>addch</STRONG>.) See the <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG> page for
118 values of predefined video attribute constants that can be usefully
119 OR'ed into characters.
122 </PRE><H3><a name="h3-Echoing-characters">Echoing characters</a></H3><PRE>
123 The <STRONG>echochar</STRONG> and <STRONG>wechochar</STRONG> routines are equivalent to a call to <STRONG>addch</STRONG>
124 followed by a call to <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG>, or a call to <STRONG>waddch</STRONG> followed by a
125 call to <STRONG>wrefresh</STRONG>. The knowledge that only a single character is being
126 output is used and, for non-control characters, a considerable
127 performance gain may be seen by using these routines instead of their
131 </PRE><H3><a name="h3-Line-Graphics">Line Graphics</a></H3><PRE>
132 The following variables may be used to add line drawing characters to
133 the screen with routines of the <STRONG>addch</STRONG> family. The default character
134 listed below is used if the <STRONG>acsc</STRONG> capability does not define a terminal-
135 specific replacement for it, or if the terminal and locale
136 configuration requires Unicode but the library is unable to use
139 The names are taken from VT100 nomenclature.
141 <STRONG>ACS</STRONG> <STRONG>ACS</STRONG> <STRONG>acsc</STRONG> <STRONG>Glyph</STRONG>
142 <STRONG>Name</STRONG> <STRONG>Default</STRONG> <STRONG>char</STRONG> <STRONG>Name</STRONG>
143 ---------------------------------------------------------
144 ACS_BLOCK # 0 solid square block
145 ACS_BOARD # h board of squares
146 ACS_BTEE + v bottom tee
147 ACS_BULLET o ~ bullet
148 ACS_CKBOARD : a checker board (stipple)
149 ACS_DARROW v . arrow pointing down
150 ACS_DEGREE ' f degree symbol
151 ACS_DIAMOND + ` diamond
152 ACS_GEQUAL > > greater-than-or-equal-to
153 ACS_HLINE - q horizontal line
154 ACS_LANTERN # i lantern symbol
155 ACS_LARROW < , arrow pointing left
156 ACS_LEQUAL < y less-than-or-equal-to
157 ACS_LLCORNER + m lower left-hand corner
158 ACS_LRCORNER + j lower right-hand corner
159 ACS_LTEE + t left tee
160 ACS_NEQUAL ! | not-equal
162 ACS_PLMINUS # g plus/minus
164 ACS_RARROW > + arrow pointing right
165 ACS_RTEE + u right tee
166 ACS_S1 - o scan line 1
167 ACS_S3 - p scan line 3
168 ACS_S7 - r scan line 7
169 ACS_S9 _ s scan line 9
170 ACS_STERLING f } pound-sterling symbol
172 ACS_UARROW ^ - arrow pointing up
173 ACS_ULCORNER + l upper left-hand corner
174 ACS_URCORNER + k upper right-hand corner
175 ACS_VLINE | x vertical line
178 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
179 All routines return the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> on success (the
180 SVr4 manuals specify only "an integer value other than <STRONG>ERR</STRONG>") upon
181 successful completion, unless otherwise noted in the preceding routine
184 Functions with a "mv" prefix first perform a cursor movement using
185 <STRONG>wmove</STRONG>, and return an error if the position is outside the window, or if
186 the window pointer is null.
188 If it is not possible to add a complete character, an error is
191 <STRONG>o</STRONG> If <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is not enabled, writing a character at the lower
192 right margin succeeds. However, an error is returned because it is
193 not possible to wrap to a new line
195 <STRONG>o</STRONG> If an error is detected when converting a multibyte character to a
196 sequence of bytes, or if it is not possible to add all of the
197 resulting bytes in the window, an error is returned.
200 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
201 Note that <STRONG>addch</STRONG>, <STRONG>mvaddch</STRONG>, <STRONG>mvwaddch</STRONG>, and <STRONG>echochar</STRONG> may be macros.
204 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
205 All these functions are described in the XSI Curses standard, Issue 4.
206 The defaults specified for forms-drawing characters apply in the POSIX
210 </PRE><H3><a name="h3-ACS-Symbols">ACS Symbols</a></H3><PRE>
211 X/Open Curses states that the <STRONG>ACS_</STRONG> definitions are <STRONG>char</STRONG> constants. For
212 the wide-character implementation (see <STRONG>curs_add_wch</STRONG>), there are
213 analogous <STRONG>WACS_</STRONG> definitions which are <STRONG>cchar_t</STRONG> constants. Some
214 implementations are problematic:
216 <STRONG>o</STRONG> Some implementations define the ACS symbols to a constant (such as
217 Solaris), while others define those to entries in an array.
219 This implementation uses an array <STRONG>acs_map</STRONG>, as done in SVr4 curses.
220 NetBSD also uses an array, actually named <STRONG>_acs_char</STRONG>, with a <STRONG>#define</STRONG>
223 <STRONG>o</STRONG> HPUX curses equates some of the <STRONG>ACS_</STRONG> symbols to the analogous <STRONG>WACS_</STRONG>
224 symbols as if the <STRONG>ACS_</STRONG> symbols were wide characters. The
225 misdefined symbols are the arrows and other symbols which are not
226 used for line-drawing.
228 <STRONG>o</STRONG> X/Open Curses (issues 2 through 7) has a typographical error for
229 the ACS_LANTERN symbol, equating its "VT100+ Character" to <STRONG>I</STRONG>
230 (capital I), while the header files for SVr4 curses and the various
231 implementations use <STRONG>i</STRONG> (lowercase).
233 None of the terminal descriptions on Unix platforms use uppercase-
234 I, except for Solaris (i.e., <STRONG>screen</STRONG>'s terminal description,
235 apparently based on the X/Open documentation around 1995). On the
236 other hand, the terminal description <EM>gs6300</EM> (AT&T PC6300 with EMOTS
237 Terminal Emulator) uses lowercase-i.
239 Some ACS symbols (ACS_S3, ACS_S7, ACS_LEQUAL, ACS_GEQUAL, ACS_PI,
240 ACS_NEQUAL, ACS_STERLING) were not documented in any publicly released
241 System V. However, many publicly available terminfos include <STRONG>acsc</STRONG>
242 strings in which their key characters (pryz{|}) are embedded, and a
243 second-hand list of their character descriptions has come to light.
244 The ACS-prefixed names for them were invented for <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>.
246 The <EM>displayed</EM> values for the <STRONG>ACS_</STRONG> and <STRONG>WACS_</STRONG> constants depend on
248 <STRONG>o</STRONG> the library configuration, i.e., <STRONG>ncurses</STRONG> versus <STRONG>ncursesw</STRONG>, where the
249 latter is capable of displaying Unicode while the former is not,
252 <STRONG>o</STRONG> whether the <EM>locale</EM> uses UTF-8 encoding.
254 In certain cases, the terminal is unable to display line-drawing
255 characters except by using UTF-8 (see the discussion of
256 <STRONG>NCURSES_NO_UTF8_ACS</STRONG> in <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>).
259 </PRE><H3><a name="h3-Character-Set">Character Set</a></H3><PRE>
260 X/Open Curses assumes that the parameter passed to <STRONG>waddch</STRONG> contains a
261 single character. As discussed in <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, that character may
262 have been more than eight bits in an SVr3 or SVr4 implementation, but
263 in the X/Open Curses model, the details are not given. The important
264 distinction between SVr4 curses and X/Open Curses is that the non-
265 character information (attributes and color) was separated from the
266 character information which is packed in a <STRONG>chtype</STRONG> to pass to <STRONG>waddch</STRONG>.
268 In this implementation, <STRONG>chtype</STRONG> holds an eight-bit character. But
269 ncurses allows multibyte characters to be passed in a succession of
270 calls to <STRONG>waddch</STRONG>. The other implementations do not do this; a call to
271 <STRONG>waddch</STRONG> passes exactly one character which may be rendered as one or
272 more cells on the screen depending on whether it is printable.
274 Depending on the locale settings, ncurses will inspect the byte passed
275 in each call to <STRONG>waddch</STRONG>, and check if the latest call will continue a
276 multibyte sequence. When a character is <EM>complete</EM>, ncurses displays the
277 character and moves to the next position in the screen.
279 If the calling application interrupts the succession of bytes in a
280 multibyte character by moving the current location (e.g., using <STRONG>wmove</STRONG>),
281 ncurses discards the partially built character, starting over again.
283 For portability to other implementations, do not rely upon this
286 <STRONG>o</STRONG> check if a character can be represented as a single byte in the
287 current locale before attempting call <STRONG>waddch</STRONG>, and
289 <STRONG>o</STRONG> call <STRONG>wadd_wch</STRONG> for characters which cannot be handled by <STRONG>waddch</STRONG>.
292 </PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
293 The <STRONG>TABSIZE</STRONG> variable is implemented in SVr4 and other versions of
294 curses, but is not part of X/Open curses (see <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG> for
297 If <EM>ch</EM> is a carriage return, the cursor is moved to the beginning of the
298 current row of the window. This is true of other implementations, but
302 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
303 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>, <STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>,
304 <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>, <STRONG>putc(3)</STRONG>
306 Comparable functions in the wide-character (ncursesw) library are
307 described in <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>.
311 ncurses 6.4 2023-09-30 <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>
315 <li><a href="#h2-NAME">NAME</a></li>
316 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
317 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
319 <li><a href="#h3-Adding-characters">Adding characters</a></li>
320 <li><a href="#h3-Echoing-characters">Echoing characters</a></li>
321 <li><a href="#h3-Line-Graphics">Line Graphics</a></li>
324 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
325 <li><a href="#h2-NOTES">NOTES</a></li>
326 <li><a href="#h2-PORTABILITY">PORTABILITY</a>
328 <li><a href="#h3-ACS-Symbols">ACS Symbols</a></li>
329 <li><a href="#h3-Character-Set">Character Set</a></li>
330 <li><a href="#h3-TABSIZE">TABSIZE</a></li>
333 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>