curs_getch(h) curs_getch(h) NAME getch, wgetch, mvgetch, mvwgetch, ungetch, has_key - get (or push back) characters from curses terminal keyboard SYNOPSIS #include <curses.h> int getch(h); 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 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 the window is not a pad, and it has been moved or modi- 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. 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. center tab(/) ; l l l l . 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/T{ Function keys; space for 64 keys is reserved. T} KEY_F(F)/T{ For 0 <= n <= 63 T} 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). 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(g) 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_MOUSE/Mouse event read KEY_MOVE/Move key KEY_NEXT/Next object key KEY_OPEN/Open key KEY_OPTIONS/Options key KEY_PREVI- OUS/Previous object key KEY_REDO/Redo key KEY_REFER- ENCE/Ref(f) key KEY_REFRESH/Refresh key KEY_REPLACE/Replace key KEY_RESIZE/Screen resized KEY_RESTART/Restart key KEY_RESUME/Resume key KEY_SAVE/Save key KEY_SBEG/Shifted beginning key KEY_SCAN- CEL/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 mes- sage 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 sus- pend key KEY_SUNDO/Shifted undo key KEY_SUSPEND/Suspend key KEY_UNDO/Undo key Keypad is arranged like this: center allbox tab(/) ; c c c . A1/up/A3 left/B2/right C1/down/C3 The has_key routine takes a key value from the above list, and returns TRUE or FALSE according as the current termi- nal 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 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. 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. 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 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 Curses 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 implementation of handled signal receipt interrupts a read(d) call in progress or not, and also (in some imple- mentations) 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 inter- rupt getch. The has_key function is unique to ncurses. We recommend that any code using it be conditionalized on the NCURSES_VERSION feature macro. SEE ALSO curses(s), curs_inopts(s), curs_mouse(e), curs_move(e), curs_refresh(h). resizeterm(m). curs_getch(h)