+ The getch, wgetch, mvgetch and mvwgetch, routines read a
character from the window. In no-delay mode, if no input
- is waiting, the value ERR is returned. In delay mode, the
+ is waiting, the value ERR is returned. In delay mode, the
program waits until the system passes text through to the
- program. Depending on the setting of cbreak, this is
- after one character (cbreak mode), or after the first new-
+ program. Depending on the setting of cbreak, this is af-
+ ter one character (cbreak mode), or after the first new-
line (nocbreak mode). In half-delay mode, the program
waits until a character is typed or the specified timeout
has been reached.
- Unless noecho has been set, then the character will also
- be echoed into the designated window according to the fol-
- lowing rules: If the character is the current erase char-
- acter, left arrow, or backspace, the cursor is moved one
- space to the left and that screen position is erased as if
- delch had been called. If the character value is any
- other KEY_ define, the user is alerted with a beep call.
- Otherwise the character is simply output to the screen.
+ If echo is enabled, and the window is not a pad, then the
+ character will also be echoed into the designated window
+ according to the following rules:
+
+ o If the character is the current erase character, left
+ arrow, or backspace, the cursor is moved one space to
+ the left and that screen position is erased as if
+ delch had been called.
+
+ o If the character value is any other KEY_ define, the
+ user is alerted with a beep call.
+
+ o If the character is a carriage-return, and if nl is
+ enabled, it is translated to a line-feed after echo-
+ ing.
+
+ o Otherwise the character is simply output to the
+ screen.
If the window is not a pad, and it has been moved or modi-
- fied since the last call to wrefresh, wrefresh will be
+ fied since the last call to wrefresh, wrefresh will be
called before another character is read.
- If keypad is TRUE, and a function key is pressed, the
- token for that function key is returned instead of the raw
- characters. Possible function keys are defined in
- <curses.h> as macros with values outside the range of
- 8-bit characters whose names begin with KEY_. Thus, a
- variable intended to hold the return value of a function
- key must be of short size or larger.
+ If keypad is TRUE, and a function key is pressed, the to-
+ ken for that function key is returned instead of the raw
+ characters. Possible function keys are defined in <curs-
+ es.h> as macros with values outside the range of 8-bit
+ characters whose names begin with KEY_. Thus, a variable
+ intended to hold the return value of a function key must
+ be of short size or larger.
When a character that could be the beginning of a function
- key is received (which, on modern terminals, means an
- escape character), curses sets a timer. If the remainder
- of the sequence does not come in within the designated
- time, the character is passed through; otherwise, the
- function key value is returned. For this reason, many
- terminals experience a delay between the time a user
- presses the escape key and the escape is returned to the
- program.
-
- The ungetch routine places ch back onto the input queue to
- be returned by the next call to wgetch. Note that there
- is, in effect, just one input queue for all windows.
-
-
- FunctionKeys
- The following function keys, defined in <curses.h>, might
- be returned by getch if keypad has been enabled. Note
- that not all of these are necessarily supported on any
+ key is received (which, on modern terminals, means an es-
+ cape character), curses sets a timer. If the remainder of
+ the sequence does not come in within the designated time,
+ the character is passed through; otherwise, the function
+ key value is returned. For this reason, many terminals
+ experience a delay between the time a user presses the es-
+ cape key and the escape is returned to the program.
+
+ The ungetch routine places ch back onto the input queue to
+ be returned by the next call to wgetch. There is just one
+ input queue for all windows.
+
+
+
+ All routines return the integer ERR upon failure and an
+ integer value other than ERR (OK in the case of ungetch())
upon successful completion.
+ ungetch
+ returns ERR if there is no more room in the FIFO.
+
+ wgetch
+ returns ERR if the window pointer is null, or if
+ its timeout expires without having any data.
+
+ Functions with a "mv" prefix first perform a cursor move-
+ ment using wmove, and return an error if the position is
+ outside the window, or if the window pointer is null.
+
Use of the escape key by a programmer for a single charac-
ter function is discouraged, as it will cause a delay of
up to one second while the keypad code looks for a follow-
ing function-key sequence.
- When using getch, wgetch, mvgetch, or mvwgetch, nocbreak
- mode (nocbreak) and echo mode (echo) should not be used at
- the same time. Depending on the state of the tty driver
- when each character is typed, the program may produce
- undesirable results.
+ Note that some keys may be the same as commonly used con-
+ trol keys, e.g., KEY_ENTER versus control/M, KEY_BACKSPACE
+ versus control/H. Some curses implementations may differ
+ according to whether they treat these control keys spe-
+ cially (and ignore the terminfo), or use the terminfo def-
+ initions. Ncurses uses the terminfo definition. If it
+ says that KEY_ENTER is control/M, getch will return
+ KEY_ENTER when you press control/M.
- Note that getch, mvgetch, and mvwgetch may be macros.
+ Generally, KEY_ENTER denotes the character(s) sent by the
+ Enter key on the numeric keypad:
- Historically, the set of keypad macros was largely defined
- by the extremely function-key-rich keyboard of the AT&T
- 7300, aka 3B1, aka Safari 4. Modern personal computers
- usually have only a small subset of these. IBM PC-style
- consoles typically support little more than KEY_UP,
- KEY_DOWN, KEY_LEFT, KEY_RIGHT, KEY_HOME, KEY_END,
- KEY_NPAGE, KEY_PPAGE, and function keys 1 through 12. The
- Ins key is usually mapped to KEY_IC.
+ o the terminal description lists the most useful keys,
+ o the Enter key on the regular keyboard is already han-
+ dled by the standard ASCII characters for carriage-re-
+ turn and line-feed,
-
-
PORTABILITY
- The *get* functions are described in the XSI Curses stan-
- dard, Issue 4. They read single-byte characters only.
- The standard specifies that they return ERR on failure,
- but specifies no error conditions.
+ o depending on whether nl or nonl was called, pressing
+ "Enter" on the regular keyboard may return either a
+ carriage-return or line-feed, and finally
- The echo behavior of these functions on input of KEY_ or
- backspace characters was not specified in the SVr4 docu-
- mentation. This description is adopted from the XSI
- Curses standard.
+ o "Enter or send" is the standard description for this
+ key.
- The behavior of getch and friends in the presence of han-
- dled signals is unspecified in the SVr4 and XSI Curses
- documentation. Under historical curses implementations,
- it varied depending on whether the operating system's
- implementation of handled signal receipt interrupts a
- read(2) call in progress or not, and also (in some imple-
- mentations) depending on whether an input timeout or non-
- blocking mode hsd been set.
+ When using getch, wgetch, mvgetch, or mvwgetch, nocbreak
+ mode (nocbreak) and echo mode (echo) should not be used at
+ the same time. Depending on the state of the tty driver
+ when each character is typed, the program may produce un-
+ desirable results.
- Programmers concerned about portability should be prepared
- for either of two cases: (a) signal receipt does not
- interrupt getch; (b) signal receipt interrupts getch and
- causes it to return ERR with errno set to EINTR. Under
- the ncurses implementation, handled signals never inter-
- rupt getch.
+ Note that getch, mvgetch, and mvwgetch may be macros.
- The has_key function is unique to ncurses. We recommend
- that any code using it be conditionalized on the
- NCURSES_VERSION feature macro.
+ Historically, the set of keypad macros was largely defined
+ by the extremely function-key-rich keyboard of the AT&T
+ 7300, aka 3B1, aka Safari 4. Modern personal computers
+ usually have only a small subset of these. IBM PC-style
+ consoles typically support little more than KEY_UP,
+ KEY_DOWN, KEY_LEFT, KEY_RIGHT, KEY_HOME, KEY_END,
+ KEY_NPAGE, KEY_PPAGE, and function keys 1 through 12. The
+ Ins key is usually mapped to KEY_IC.
+ The *get* functions are described in the XSI Curses stan-
+ dard, Issue 4. They read single-byte characters only.
+ The standard specifies that they return ERR on failure,
+ but specifies no error conditions.
+ The echo behavior of these functions on input of KEY_ or
+ backspace characters was not specified in the SVr4 docu-
+ mentation. This description is adopted from the XSI Curs-
+ es standard.
+ The behavior of getch and friends in the presence of han-
+ dled signals is unspecified in the SVr4 and XSI Curses
+ documentation. Under historical curses implementations,
+ it varied depending on whether the operating system's im-
+ plementation of handled signal receipt interrupts a
+ read(2) call in progress or not, and also (in some imple-
+ mentations) depending on whether an input timeout or non-
+ blocking mode has been set.
+ Programmers concerned about portability should be prepared
+ for either of two cases: (a) signal receipt does not in-
+ terrupt getch; (b) signal receipt interrupts getch and
+ causes it to return ERR with errno set to EINTR. Under
+ the ncurses implementation, handled signals never inter-
+ rupt getch.
+ The has_key function is unique to ncurses. We recommend
+ that any code using it be conditionalized on the NCURS-
+ ES_VERSION feature macro.
+