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43 <H1 class="no-header">curs_addch 3x 2024-05-11 ncurses 6.5 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-waddch">waddch</a></H3><PRE>
70 <STRONG>waddch</STRONG> writes the <EM>curses</EM> character <EM>ch</EM> to the window <EM>win</EM>, then advances
71 the cursor position, analogously to the standard C library's
72 <STRONG>putchar(3)</STRONG>. <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG> describes the variants of this function.
74 If advancement occurs at the right margin,
76 <STRONG>o</STRONG> the cursor automatically wraps to the beginning of the next line,
79 <STRONG>o</STRONG> if it was at the bottom of the scrolling region, and if
80 <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> is enabled for <EM>win</EM>, the scrolling region scrolls up
83 If <EM>ch</EM> is a backspace, carriage return, line feed, or tab, the cursor
84 moves appropriately within the window.
86 <STRONG>o</STRONG> Backspace moves the cursor one character left; at the left margin
87 of a window, it does nothing.
89 <STRONG>o</STRONG> Carriage return moves the cursor to the left margin on the current
92 <STRONG>o</STRONG> Line feed does a <STRONG><A HREF="curs_clear.3x.html">clrtoeol(3x)</A></STRONG>, then advances as if from the right
95 <STRONG>o</STRONG> Tab advances the cursor to the next tab stop (possibly on the next
96 line); these are placed at every eighth column by default. Alter
97 the tab interval with the <STRONG>TABSIZE</STRONG> extension; see
98 <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>.
100 If <EM>ch</EM> is any other nonprintable character, it is drawn in printable
101 form using the same convention as <STRONG><A HREF="unctrl.3x.html">unctrl(3x)</A></STRONG>.
103 Calling <STRONG><A HREF="curs_inch.3x.html">winch(3x)</A></STRONG> on the location of a nonprintable character does not
104 return the character itself, but its <STRONG><A HREF="unctrl.3x.html">unctrl(3x)</A></STRONG> representation.
106 The object or expression <EM>ch</EM> may contain attributes and/or a color pair
107 identifier. (A character with its attributes can be copied from place
108 to place using <STRONG><A HREF="curs_inch.3x.html">winch(3x)</A></STRONG> and <STRONG>waddch</STRONG>.) See <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG> for values of
109 predefined video attribute constants that can be usefully "or"ed with
113 </PRE><H3><a name="h3-wechochar">wechochar</a></H3><PRE>
114 <STRONG>echochar</STRONG> and <STRONG>wechochar</STRONG> are equivalent to calling (<STRONG>w</STRONG>)<STRONG>addch</STRONG> followed by
115 (<STRONG>w</STRONG>)<STRONG>refresh</STRONG>. <EM>curses</EM> interprets these functions as a hint that only a
116 single character is being output; for non-control characters, a
117 considerable performance gain may be enjoyed by employing them.
120 </PRE><H3><a name="h3-Forms-Drawing-Characters">Forms-Drawing Characters</a></H3><PRE>
121 <EM>curses</EM> defines macros starting with <STRONG>ACS_</STRONG> that can be used with <STRONG>waddch</STRONG>
122 to write line-drawing and other special characters to the screen.
123 <EM>ncurses</EM> terms these <EM>forms-drawing</EM> <EM>characters.</EM> The ACS default listed
124 below is used if the <STRONG>acs_chars</STRONG> (<STRONG>acsc</STRONG>) <EM>terminfo</EM> capability does not
125 define a terminal-specific replacement for it, or if the terminal and
126 locale configuration requires Unicode to access these characters but
127 the library is unable to use Unicode. The "acsc char" column
128 corresponds to how the characters are specified in the <STRONG>acs_chars</STRONG> (<STRONG>acsc</STRONG>)
129 string capability, and the characters in it may appear on the screen if
130 the terminal type's database entry incorrectly advertises ACS support.
131 The name "ACS" originates in the Alternate Character Set feature of the
134 <STRONG>ACS</STRONG> <STRONG>acsc</STRONG>
135 <STRONG>Symbol</STRONG> <STRONG>Default</STRONG> <STRONG>char</STRONG> <STRONG>Glyph</STRONG> <STRONG>Name</STRONG>
136 ------------------------------------------------------------------------
137 <STRONG>ACS_BLOCK</STRONG> # 0 solid square block
138 <STRONG>ACS_BOARD</STRONG> # h board of squares
139 <STRONG>ACS_BTEE</STRONG> + v bottom tee
140 <STRONG>ACS_BULLET</STRONG> o ~ bullet
141 <STRONG>ACS_CKBOARD</STRONG> : a checker board (stipple)
142 <STRONG>ACS_DARROW</STRONG> v . arrow pointing down
143 <STRONG>ACS_DEGREE</STRONG> ' f degree symbol
144 <STRONG>ACS_DIAMOND</STRONG> + ` diamond
145 <STRONG>ACS_GEQUAL</STRONG> > > greater-than-or-equal-to
146 <STRONG>ACS_HLINE</STRONG> - q horizontal line
147 <STRONG>ACS_LANTERN</STRONG> # i lantern symbol
148 <STRONG>ACS_LARROW</STRONG> < , arrow pointing left
149 <STRONG>ACS_LEQUAL</STRONG> < y less-than-or-equal-to
150 <STRONG>ACS_LLCORNER</STRONG> + m lower left-hand corner
151 <STRONG>ACS_LRCORNER</STRONG> + j lower right-hand corner
152 <STRONG>ACS_LTEE</STRONG> + t left tee
153 <STRONG>ACS_NEQUAL</STRONG> ! | not-equal
154 <STRONG>ACS_PI</STRONG> * { greek pi
155 <STRONG>ACS_PLMINUS</STRONG> # g plus/minus
156 <STRONG>ACS_PLUS</STRONG> + n plus
157 <STRONG>ACS_RARROW</STRONG> > + arrow pointing right
158 <STRONG>ACS_RTEE</STRONG> + u right tee
159 <STRONG>ACS_S1</STRONG> - o scan line 1
160 <STRONG>ACS_S3</STRONG> - p scan line 3
161 <STRONG>ACS_S7</STRONG> - r scan line 7
162 <STRONG>ACS_S9</STRONG> _ s scan line 9
163 <STRONG>ACS_STERLING</STRONG> f } pound-sterling symbol
164 <STRONG>ACS_TTEE</STRONG> + w top tee
165 <STRONG>ACS_UARROW</STRONG> ^ - arrow pointing up
166 <STRONG>ACS_ULCORNER</STRONG> + l upper left-hand corner
167 <STRONG>ACS_URCORNER</STRONG> + k upper right-hand corner
168 <STRONG>ACS_VLINE</STRONG> | x vertical line
171 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
172 These functions return <STRONG>OK</STRONG> on success and <STRONG>ERR</STRONG> on failure.
174 In <EM>ncurses</EM>, <STRONG>waddch</STRONG> returns <STRONG>ERR</STRONG> if
176 <STRONG>o</STRONG> <EM>win</EM> is <STRONG>NULL</STRONG>,
178 <STRONG>o</STRONG> wrapping to a new line is impossible because <STRONG><A HREF="scrollok.3x.html">scrollok(3x)</A></STRONG> has not
179 been called on <EM>win</EM> when a write to its bottom right location is
182 <STRONG>o</STRONG> it is not possible to add a complete character at the cursor
185 The last may be due to different causes:
187 <STRONG>o</STRONG> conversion of a multibyte character to a byte sequence can fail, or
189 <STRONG>o</STRONG> at least one of the bytes resulting from conversion from a
190 multibyte sequence cannot be added to the window. See section
191 "PORTABILITY" below regarding the use of <STRONG>waddch</STRONG> with multibyte
194 Functions prefixed with "mv" first perform cursor movement and fail if
195 the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries.
198 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
199 <STRONG>addch</STRONG>, <STRONG>mvaddch</STRONG>, <STRONG>mvwaddch</STRONG>, and <STRONG>echochar</STRONG> may be implemented as macros.
202 </PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
204 </PRE><H3><a name="h3-TABSIZE">TABSIZE</a></H3><PRE>
205 SVr4 and other versions of <EM>curses</EM> implement the <STRONG>TABSIZE</STRONG> variable, but
206 X/Open Curses does not specify it; see <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>.
209 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
210 X/Open Curses, Issue 4 describes these functions. It specifies no
211 error conditions for them.
213 SVr4 <EM>curses</EM> describes a successful return value only as "an integer
214 value other than <STRONG>ERR</STRONG>".
216 The defaults specified for forms-drawing characters apply in the POSIX
220 </PRE><H3><a name="h3-ACS-Symbols">ACS Symbols</a></H3><PRE>
221 X/Open Curses states that the <STRONG>ACS_</STRONG> definitions are <EM>char</EM> constants.
223 Some implementations are problematic.
225 <STRONG>o</STRONG> Solaris <EM>curses</EM>, for example, defines the ACS symbols as constants;
226 others define them as elements of an array.
228 This implementation uses an array, <STRONG>acs_map</STRONG>, as did SVr4 <EM>curses</EM>.
229 NetBSD also uses an array, actually named <STRONG>_acs_char</STRONG>, with a <STRONG>#define</STRONG>
232 <STRONG>o</STRONG> HP-UX <EM>curses</EM> equates some of the <STRONG>ACS_</STRONG> symbols to the analogous
233 <STRONG>WACS_</STRONG> symbols as if the <STRONG>ACS_</STRONG> symbols were wide characters (see
234 <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>). The misdefined symbols are the arrows and
235 others that are not used for line drawing.
237 <STRONG>o</STRONG> X/Open Curses (Issues 2 through 7) has a typographical error for
238 the <STRONG>ACS_LANTERN</STRONG> symbol, equating its "VT100+ Character" to "I"
239 (capital I), while the header files for SVr4 <EM>curses</EM> and other
240 implementations use "i" (small i).
242 None of the terminal descriptions on Unix platforms use uppercase
243 I, except for Solaris (in its <EM>terminfo</EM> entry for <STRONG>screen(1)</STRONG>,
244 apparently based on the X/Open documentation around 1995). On the
245 other hand, its <STRONG>gs6300</STRONG> (AT&T PC6300 with EMOTS Terminal Emulator)
246 description uses lowercase i.
248 Some ACS symbols (<STRONG>ACS_S3</STRONG>, <STRONG>ACS_S7</STRONG>, <STRONG>ACS_LEQUAL</STRONG>, <STRONG>ACS_GEQUAL</STRONG>, <STRONG>ACS_PI</STRONG>,
249 <STRONG>ACS_NEQUAL</STRONG>, and <STRONG>ACS_STERLING</STRONG>) were not documented in any publicly
250 released System V. However, many publicly available <EM>terminfo</EM> entries
251 include <STRONG>acsc</STRONG> capabilities in which their key characters (<STRONG>pryz{|}</STRONG>) are
252 embedded, and a second-hand list of their character descriptions has
253 come to light. The <EM>ncurses</EM> developers invented ACS-prefixed names for
256 The <EM>displayed</EM> values of <STRONG>ACS_</STRONG> constants depend on
258 <STRONG>o</STRONG> the <EM>ncurses</EM> ABI--for example, wide-character versus non-wide-
259 character configurations (the former is capable of displaying
260 Unicode while the latter is not), and
262 <STRONG>o</STRONG> whether the locale uses UTF-8 encoding.
264 In certain cases, the terminal is unable to display forms-drawing
265 characters <EM>except</EM> by using UTF-8; see the discussion of the
266 <EM>NCURSES</EM><STRONG>_</STRONG><EM>NO</EM><STRONG>_</STRONG><EM>UTF8</EM><STRONG>_</STRONG><EM>ACS</EM> environment variable in <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>.
269 </PRE><H3><a name="h3-Character-Set">Character Set</a></H3><PRE>
270 X/Open Curses assumes that the parameter passed to <STRONG>waddch</STRONG> contains a
271 single character. That character may have been more than eight bits
272 wide in an SVr3 or SVr4 implementation, but X/Open Curses leaves the
273 width of a non-wide character code unspecified. The standard further
274 does not specify the internal structure of a <EM>chtype</EM>, though the use of
275 bit operations to combine the character code with attributes and a
276 color pair identifier into a <EM>chtype</EM> for passage to <STRONG>waddch</STRONG> is common. A
277 portable application uses only the macros discussed in <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG> to
278 manipulate a <EM>chtype</EM>.
280 In <EM>ncurses</EM>, <EM>chtype</EM> holds an eight-bit character, but the library allows
281 a multibyte character to be passed in a succession of calls to <STRONG>waddch</STRONG>.
282 Other implementations do not; a <STRONG>waddch</STRONG> call transmits exactly one
283 character, which may be rendered in one or more screen locations
284 depending on whether it is printable (see <STRONG><A HREF="unctrl.3x.html">unctrl(3x)</A></STRONG>). Depending on
285 the locale, <EM>ncurses</EM> inspects the byte passed in each <STRONG>waddch</STRONG> call and
286 checks whether the latest call continues a multibyte sequence. When a
287 character is <EM>complete</EM>, <EM>ncurses</EM> displays the character and advances the
288 cursor. If the calling application interrupts the succession of bytes
289 in a multibyte character sequence by changing the current location--for
290 example, with <STRONG><A HREF="curs_move.3x.html">wmove(3x)</A></STRONG>--<EM>ncurses</EM> discards the incomplete character.
292 For portability to other implementations, do not rely upon the
293 foregoing behavior. Check whether a character can be represented as a
294 single byte in the current locale.
296 <STRONG>o</STRONG> If it can, call either <STRONG>waddch</STRONG> or <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG>.
298 <STRONG>o</STRONG> If it cannot, use only <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG>.
301 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
302 <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG> describes comparable functions of the <EM>ncurses</EM> library
303 in its wide-character configuration (<EM>ncursesw</EM>).
305 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_addchstr.3x.html">curs_addchstr(3x)</A></STRONG>, <STRONG><A HREF="curs_addstr.3x.html">curs_addstr(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>,
306 <STRONG><A HREF="curs_clear.3x.html">curs_clear(3x)</A></STRONG>, <STRONG><A HREF="curs_inch.3x.html">curs_inch(3x)</A></STRONG>, <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>,
307 <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>, <STRONG>putchar(3)</STRONG>
311 ncurses 6.5 2024-05-11 <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-waddch">waddch</a></li>
320 <li><a href="#h3-wechochar">wechochar</a></li>
321 <li><a href="#h3-Forms-Drawing-Characters">Forms-Drawing Characters</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-EXTENSIONS">EXTENSIONS</a>
328 <li><a href="#h3-TABSIZE">TABSIZE</a></li>
331 <li><a href="#h2-PORTABILITY">PORTABILITY</a>
333 <li><a href="#h3-ACS-Symbols">ACS Symbols</a></li>
334 <li><a href="#h3-Character-Set">Character Set</a></li>
337 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>