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42 <H1 class="no-header">curs_getch 3x</H1>
44 <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG> <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>
50 <H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>getch</STRONG>, <STRONG>wgetch</STRONG>, <STRONG>mvgetch</STRONG>, <STRONG>mvwgetch</STRONG>, <STRONG>ungetch</STRONG>, <STRONG>has_key</STRONG> - get
52 (or push back) characters from <STRONG>curses</STRONG> terminal keyboard
56 <H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
57 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
59 <STRONG>int</STRONG> <STRONG>getch(void);</STRONG>
60 <STRONG>int</STRONG> <STRONG>wgetch(WINDOW</STRONG> <STRONG>*</STRONG><EM>win);</EM>
61 <STRONG>int</STRONG> <STRONG>mvgetch(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>);</STRONG>
62 <STRONG>int</STRONG> <STRONG>mvwgetch(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>
63 <STRONG>int</STRONG> <STRONG>ungetch(int</STRONG> <EM>ch</EM><STRONG>);</STRONG>
64 <STRONG>int</STRONG> <STRONG>has_key(int</STRONG> <EM>ch</EM><STRONG>);</STRONG>
68 <H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
71 <H3><a name="h3-Reading-characters">Reading characters</a></H3><PRE>
72 The <STRONG>getch</STRONG>, <STRONG>wgetch</STRONG>, <STRONG>mvgetch</STRONG> and <STRONG>mvwgetch</STRONG>, routines read a
73 character from the window. In no-delay mode, if no input
74 is waiting, the value <STRONG>ERR</STRONG> is returned. In delay mode, the
75 program waits until the system passes text through to the
76 program. Depending on the setting of <STRONG>cbreak</STRONG>, this is af-
77 ter one character (cbreak mode), or after the first new-
78 line (nocbreak mode). In half-delay mode, the program
79 waits until a character is typed or the specified timeout
82 If <STRONG>echo</STRONG> is enabled, and the window is not a pad, then the
83 character will also be echoed into the designated window
84 according to the following rules:
86 <STRONG>o</STRONG> If the character is the current erase character, left
87 arrow, or backspace, the cursor is moved one space to
88 the left and that screen position is erased as if
89 <STRONG>delch</STRONG> had been called.
91 <STRONG>o</STRONG> If the character value is any other <STRONG>KEY_</STRONG> define, the
92 user is alerted with a <STRONG>beep</STRONG> call.
94 <STRONG>o</STRONG> If the character is a carriage-return, and if <STRONG>nl</STRONG> is
95 enabled, it is translated to a line-feed after echo-
98 <STRONG>o</STRONG> Otherwise the character is simply output to the
101 If the window is not a pad, and it has been moved or modi-
102 fied since the last call to <STRONG>wrefresh</STRONG>, <STRONG>wrefresh</STRONG> will be
103 called before another character is read.
107 <H3><a name="h3-Keypad-mode">Keypad mode</a></H3><PRE>
108 If <STRONG>keypad</STRONG> is <STRONG>TRUE</STRONG>, and a function key is pressed, the to-
109 ken for that function key is returned instead of the raw
110 characters. Possible function keys are defined in <STRONG><curs-</STRONG>
111 <STRONG>es.h></STRONG> as macros with values outside the range of 8-bit
112 characters whose names begin with <STRONG>KEY_</STRONG>. Thus, a variable
113 intended to hold the return value of a function key must
114 be of short size or larger.
116 When a character that could be the beginning of a function
117 key is received (which, on modern terminals, means an es-
118 cape character), <STRONG>curses</STRONG> sets a timer. If the remainder of
119 the sequence does not come in within the designated time,
120 the character is passed through; otherwise, the function
121 key value is returned. For this reason, many terminals
122 experience a delay between the time a user presses the es-
123 cape key and the escape is returned to the program.
127 <H3><a name="h3-Ungetting-characters">Ungetting characters</a></H3><PRE>
128 The <STRONG>ungetch</STRONG> routine places <EM>ch</EM> back onto the input queue to
129 be returned by the next call to <STRONG>wgetch</STRONG>. There is just one
130 input queue for all windows.
134 <H3><a name="h3-Predefined-key-codes">Predefined key-codes</a></H3><PRE>
135 The following special keys, defined in <STRONG><curses.h></STRONG>, may be
136 returned by <STRONG>getch</STRONG> if <STRONG>keypad</STRONG> has been enabled. Not all of
137 these are necessarily supported on any particular termi-
140 <EM>Name</EM> <EM>Key</EM> <EM>name</EM>
141 -------------------------------------------------
143 KEY_DOWN The four arrow keys ...
147 KEY_HOME Home key (upward+left arrow)
148 KEY_BACKSPACE Backspace
149 KEY_F0 Function keys; space for 64 keys
151 KEY_F(<EM>n</EM>) For 0 <= <EM>n</EM> <= 63
154 KEY_DC Delete character
155 KEY_IC Insert char or enter insert mode
156 KEY_EIC Exit insert char mode
157 KEY_CLEAR Clear screen
158 KEY_EOS Clear to end of screen
159 KEY_EOL Clear to end of line
160 KEY_SF Scroll 1 line forward
161 KEY_SR Scroll 1 line backward (reverse)
163 KEY_PPAGE Previous page
166 KEY_CATAB Clear all tabs
167 KEY_ENTER Enter or send
168 KEY_SRESET Soft (partial) reset
169 KEY_RESET Reset or hard reset
170 KEY_PRINT Print or copy
171 KEY_LL Home down or bottom (lower left)
172 KEY_A1 Upper left of keypad
173 KEY_A3 Upper right of keypad
174 KEY_B2 Center of keypad
175 KEY_C1 Lower left of keypad
176 KEY_C3 Lower right of keypad
177 KEY_BTAB Back tab key
178 KEY_BEG Beg(inning) key
179 KEY_CANCEL Cancel key
181 KEY_COMMAND Cmd (command) key
183 KEY_CREATE Create key
190 KEY_MESSAGE Message key
191 KEY_MOUSE Mouse event read
193 KEY_NEXT Next object key
195 KEY_OPTIONS Options key
196 KEY_PREVIOUS Previous object key
198 KEY_REFERENCE Ref(erence) key
199 KEY_REFRESH Refresh key
200 KEY_REPLACE Replace key
201 KEY_RESIZE Screen resized
202 KEY_RESTART Restart key
203 KEY_RESUME Resume key
205 KEY_SBEG Shifted beginning key
206 KEY_SCANCEL Shifted cancel key
207 KEY_SCOMMAND Shifted command key
208 KEY_SCOPY Shifted copy key
209 KEY_SCREATE Shifted create key
210 KEY_SDC Shifted delete char key
211 KEY_SDL Shifted delete line key
212 KEY_SELECT Select key
213 KEY_SEND Shifted end key
214 KEY_SEOL Shifted clear line key
215 KEY_SEXIT Shifted exit key
216 KEY_SFIND Shifted find key
217 KEY_SHELP Shifted help key
218 KEY_SHOME Shifted home key
219 KEY_SIC Shifted input key
220 KEY_SLEFT Shifted left arrow key
221 KEY_SMESSAGE Shifted message key
222 KEY_SMOVE Shifted move key
223 KEY_SNEXT Shifted next key
224 KEY_SOPTIONS Shifted options key
225 KEY_SPREVIOUS Shifted prev key
226 KEY_SPRINT Shifted print key
227 KEY_SREDO Shifted redo key
228 KEY_SREPLACE Shifted replace key
229 KEY_SRIGHT Shifted right arrow
230 KEY_SRSUME Shifted resume key
231 KEY_SSAVE Shifted save key
232 KEY_SSUSPEND Shifted suspend key
233 KEY_SUNDO Shifted undo key
234 KEY_SUSPEND Suspend key
237 Keypad is arranged like this:
239 +-----+------+-------+
240 | <STRONG>A1</STRONG> | <STRONG>up</STRONG> | <STRONG>A3</STRONG> |
241 +-----+------+-------+
242 |<STRONG>left</STRONG> | <STRONG>B2</STRONG> | <STRONG>right</STRONG> |
243 +-----+------+-------+
244 | <STRONG>C1</STRONG> | <STRONG>down</STRONG> | <STRONG>C3</STRONG> |
245 +-----+------+-------+
246 A few of these predefined values do <EM>not</EM> correspond to a
249 <STRONG>o</STRONG> <STRONG>KEY_RESIZE</STRONG> is returned when the <STRONG>SIGWINCH</STRONG> signal has
250 been detected (see <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG> and <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG>).
251 This code is returned whether or not <STRONG>keypad</STRONG> has been
254 <STRONG>o</STRONG> <STRONG>KEY_MOUSE</STRONG> is returned for mouse-events (see
255 <STRONG><A HREF="curs_mouse.3x.html">curs_mouse(3x)</A></STRONG>). This code relies upon whether or not
256 <STRONG><A HREF="keypad.3x.html">keypad(3x)</A></STRONG> has been enabled, because (e.g., with <EM>xterm</EM>
257 mouse prototocol) ncurses must read escape sequences,
258 just like a function key.
262 <H3><a name="h3-Testing-key-codes">Testing key-codes</a></H3><PRE>
263 The <STRONG>has_key</STRONG> routine takes a key-code value from the above
264 list, and returns <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG> according to whether the
265 current terminal type recognizes a key with that value.
267 The library also supports these extensions:
269 <STRONG>define_key</STRONG>
270 defines a key-code for a given string (see <STRONG>de-</STRONG>
271 <STRONG><A HREF="define_key.3x.html">fine_key(3x)</A></STRONG>).
273 <STRONG>key_defined</STRONG>
274 checks if there is a key-code defined for a given
275 string (see <STRONG><A HREF="key_defined.3x.html">key_defined(3x)</A></STRONG>).
279 <H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
280 All routines return the integer <STRONG>ERR</STRONG> upon failure and an
281 integer value other than <STRONG>ERR</STRONG> (<STRONG>OK</STRONG> in the case of ungetch())
282 upon successful completion.
284 <STRONG>ungetch</STRONG>
285 returns ERR if there is no more room in the FIFO.
287 <STRONG>wgetch</STRONG>
288 returns ERR if the window pointer is null, or if
289 its timeout expires without having any data.
291 Functions with a "mv" prefix first perform a cursor move-
292 ment using <STRONG>wmove</STRONG>, and return an error if the position is
293 outside the window, or if the window pointer is null.
297 <H2><a name="h2-NOTES">NOTES</a></H2><PRE>
298 Use of the escape key by a programmer for a single charac-
299 ter function is discouraged, as it will cause a delay of
300 up to one second while the keypad code looks for a follow-
301 ing function-key sequence.
303 Some keys may be the same as commonly used control keys,
304 e.g., <STRONG>KEY_ENTER</STRONG> versus control/M, <STRONG>KEY_BACKSPACE</STRONG> versus
305 control/H. Some curses implementations may differ accord-
306 ing to whether they treat these control keys specially
307 (and ignore the terminfo), or use the terminfo defini-
308 tions. <STRONG>Ncurses</STRONG> uses the terminfo definition. If it says
309 that <STRONG>KEY_ENTER</STRONG> is control/M, <STRONG>getch</STRONG> will return <STRONG>KEY_ENTER</STRONG>
310 when you press control/M.
312 Generally, <STRONG>KEY_ENTER</STRONG> denotes the character(s) sent by the
313 <EM>Enter</EM> key on the numeric keypad:
315 <STRONG>o</STRONG> the terminal description lists the most useful keys,
317 <STRONG>o</STRONG> the <EM>Enter</EM> key on the regular keyboard is already han-
318 dled by the standard ASCII characters for carriage-re-
321 <STRONG>o</STRONG> depending on whether <STRONG>nl</STRONG> or <STRONG>nonl</STRONG> was called, pressing
322 "Enter" on the regular keyboard may return either a
323 carriage-return or line-feed, and finally
325 <STRONG>o</STRONG> "Enter or send" is the standard description for this
328 When using <STRONG>getch</STRONG>, <STRONG>wgetch</STRONG>, <STRONG>mvgetch</STRONG>, or <STRONG>mvwgetch</STRONG>, nocbreak
329 mode (<STRONG>nocbreak</STRONG>) and echo mode (<STRONG>echo</STRONG>) should not be used at
330 the same time. Depending on the state of the tty driver
331 when each character is typed, the program may produce un-
334 Note that <STRONG>getch</STRONG>, <STRONG>mvgetch</STRONG>, and <STRONG>mvwgetch</STRONG> may be macros.
336 Historically, the set of keypad macros was largely defined
337 by the extremely function-key-rich keyboard of the AT&T
338 7300, aka 3B1, aka Safari 4. Modern personal computers
339 usually have only a small subset of these. IBM PC-style
340 consoles typically support little more than <STRONG>KEY_UP</STRONG>,
341 <STRONG>KEY_DOWN</STRONG>, <STRONG>KEY_LEFT</STRONG>, <STRONG>KEY_RIGHT</STRONG>, <STRONG>KEY_HOME</STRONG>, <STRONG>KEY_END</STRONG>,
342 <STRONG>KEY_NPAGE</STRONG>, <STRONG>KEY_PPAGE</STRONG>, and function keys 1 through 12. The
343 Ins key is usually mapped to <STRONG>KEY_IC</STRONG>.
347 <H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
348 The *get* functions are described in the XSI Curses stan-
349 dard, Issue 4. They read single-byte characters only.
350 The standard specifies that they return <STRONG>ERR</STRONG> on failure,
351 but specifies no error conditions.
353 The echo behavior of these functions on input of <STRONG>KEY_</STRONG> or
354 backspace characters was not specified in the SVr4 docu-
355 mentation. This description is adopted from the XSI Curs-
358 The behavior of <STRONG>getch</STRONG> and friends in the presence of han-
359 dled signals is unspecified in the SVr4 and XSI Curses
360 documentation. Under historical curses implementations,
361 it varied depending on whether the operating system's im-
362 plementation of handled signal receipt interrupts a
363 <STRONG>read(2)</STRONG> call in progress or not, and also (in some imple-
364 mentations) depending on whether an input timeout or non-
365 blocking mode has been set.
367 <STRONG>KEY_MOUSE</STRONG> is mentioned in XSI Curses, along with a few re-
368 lated terminfo capabilities, but no higher-level functions
369 use the feature. The implementation in ncurses is an ex-
372 <STRONG>KEY_RESIZE</STRONG> is an extension first implemented for ncurses.
373 NetBSD curses later added this extension.
375 Programmers concerned about portability should be prepared
376 for either of two cases: (a) signal receipt does not in-
377 terrupt <STRONG>getch</STRONG>; (b) signal receipt interrupts <STRONG>getch</STRONG> and
378 causes it to return ERR with <STRONG>errno</STRONG> set to <STRONG>EINTR</STRONG>. Under
379 the <STRONG>ncurses</STRONG> implementation, handled signals never inter-
380 rupt <STRONG>getch</STRONG>.
382 The <STRONG>has_key</STRONG> function is unique to <STRONG>ncurses</STRONG>. We recommend
383 that any code using it be conditionalized on the <STRONG>NCURS-</STRONG>
384 <STRONG>ES_VERSION</STRONG> feature macro.
388 <H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
389 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_inopts.3x.html">curs_inopts(3x)</A></STRONG>, <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>,
390 <STRONG><A HREF="curs_mouse.3x.html">curs_mouse(3x)</A></STRONG>, <STRONG><A HREF="curs_move.3x.html">curs_move(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG>re-</STRONG>
391 <STRONG><A HREF="resizeterm.3x.html">sizeterm(3x)</A></STRONG>.
393 Comparable functions in the wide-character (ncursesw) li-
394 brary are described in <STRONG><A HREF="curs_get_wch.3x.html">curs_get_wch(3x)</A></STRONG>.
398 <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>
402 <li><a href="#h2-NAME">NAME</a></li>
403 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
404 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
406 <li><a href="#h3-Reading-characters">Reading characters</a></li>
407 <li><a href="#h3-Keypad-mode">Keypad mode</a></li>
408 <li><a href="#h3-Ungetting-characters">Ungetting characters</a></li>
409 <li><a href="#h3-Predefined-key-codes">Predefined key-codes</a></li>
410 <li><a href="#h3-Testing-key-codes">Testing key-codes</a></li>
413 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
414 <li><a href="#h2-NOTES">NOTES</a></li>
415 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
416 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>