curs_getch(3X)

NAME
getch, wgetch, mvgetch, mvwgetch, ungetch - get (or push back) characters from curses terminal keyboard

SYNOPSIS
#include <curses.h> int getch(void);
int wgetch(WINDOW *win);
int mvgetch(int y, int x);
int mvwgetch(WINDOW *win, int y, int x);
int ungetch(int ch);
int has_key(int ch);

DESCRIPTION
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 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 newline (nocbreak mode). In half-delay mode, the program waits until a character is typed or the specified timeout has been reached. If noecho has been set, then the character will also be echoed into the designated window according to the following rules: 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. 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 the window is not a pad, and it has been moved or modified 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. 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.

  Function Keys
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 particular terminal.
__________________________________________________________________
Name                 Key name
__________________________________________________________________
KEY_BREAK            Break key
KEY_DOWN             The four arrow keys ...
KEY_UP
KEY_LEFT
KEY_RIGHT
KEY_HOME             Home key (upward+left arrow)
KEY_BACKSPACE        Backspace
KEY_F0               Function keys; space for 64 keys is reserved.
KEY_F(n)             For 0 < n < 63
KEY_DL               Delete line
KEY_IL               Insert line
KEY_DC               Delete character
KEY_IC               Insert char or enter insert mode
KEY_EIC              Exit insert char mode
KEY_CLEAR            Clear screen
KEY_EOS              Clear to end of screen
KEY_EOL              Clear to end of line
KEY_SF               Scroll 1 line forward
KEY_SR               Scroll 1 line backward (reverse)
KEY_NPAGE            Next page
KEY_PPAGE            Previous page
KEY_STAB             Set tab
KEY_CTAB             Clear tab
KEY_CATAB            Clear all tabs
KEY_ENTER            Enter or send
KEY_SRESET           Soft (partial) reset
KEY_RESET            Reset or hard reset
KEY_PRINT            Print or copy
KEY_LL               Home down or bottom (lower left).  Keypad is
                     arranged like this:
                          A1    up    A3
                         left   B2   right
                          C1   down   C3
KEY_A1               Upper left of keypad
KEY_A3               Upper right of keypad
KEY_B2               Center of keypad
KEY_C1               Lower left of keypad
KEY_C3               Lower right of keypad
KEY_BTAB             Back tab key
KEY_BEG              Beg(inning) key
KEY_CANCEL           Cancel key
KEY_CLOSE            Close key
KEY_COMMAND          Cmd (command) key
KEY_COPY             Copy key
KEY_CREATE           Create key
KEY_END              End key
KEY_EXIT             Exit key
KEY_FIND             Find key
KEY_HELP             Help key
KEY_MARK             Mark key
KEY_MESSAGE          Message key
KEY_MOVE             Move key
KEY_NEXT             Next object key
KEY_OPEN             Open key
KEY_OPTIONS          Options key
KEY_PREVIOUS         Previous object key
KEY_REDO             Redo key
KEY_REFERENCE        Ref(erence) key
KEY_REFRESH          Refresh key
KEY_REPLACE          Replace key
KEY_RESTART          Restart key
KEY_RESUME           Resume key
KEY_SAVE             Save key
KEY_SBEG             Shifted beginning key
KEY_SCANCEL          Shifted cancel key
KEY_SCOMMAND         Shifted command key
KEY_SCOPY            Shifted copy key
KEY_SCREATE          Shifted create key
KEY_SDC              Shifted delete char key
KEY_SDL              Shifted delete line key
KEY_SELECT           Select key
KEY_SEND             Shifted end key
KEY_SEOL             Shifted clear line key
KEY_SEXIT            Shifted exit key
KEY_SFIND            Shifted find key
KEY_SHELP            Shifted help key
KEY_SHOME            Shifted home key
KEY_SIC              Shifted input key
KEY_SLEFT            Shifted left arrow key
KEY_SMESSAGE         Shifted message key
KEY_SMOVE            Shifted move key
KEY_SNEXT            Shifted next key
KEY_SOPTIONS         Shifted options key
KEY_SPREVIOUS        Shifted prev key
KEY_SPRINT           Shifted print key
KEY_SREDO            Shifted redo key
KEY_SREPLACE         Shifted replace key
KEY_SRIGHT           Shifted right arrow
KEY_SRSUME           Shifted resume key
KEY_SSAVE            Shifted save key
KEY_SSUSPEND         Shifted suspend key
KEY_SUNDO            Shifted undo key
KEY_SUSPEND          Suspend key
KEY_UNDO             Undo key
The has_key routine takes a key value from the above list, and returns TRUE or FALSE according as the current terminal type recognizes a key with that value.

RETURN VALUE
All routines return the integer ERR upon failure and an integer value other than ERR (OK in the case of ungetch()) upon successful completion.

NOTES
Use of the escape key by a programmer for a single character function is discouraged, as it will cause a delay of up to one second while the keypad code looks for a following 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 getch, mvgetch, and mvwgetch may be macros. 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.

PORTABILITY
The *get* functions are described in the XSI Curses standard, 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 documentation. This description is adopted from the XSI Curses standard. The behavior of getch and friends in the presence of handled 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 implementations) depending on whether an input timeout or non-blocking mode hsd been set. 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 interrupt getch. The has_key function is unique to ncurses. We recommend that any code using it be conditionalized on the NCURSES feature macro.

SEE ALSO
curses(3X), curs_inopts(3X), curs_move(3X), curs_refresh(3X).