NAME

curses_input, getch, wgetch, mvgetch, mvwgetch, define_key, keyok, has_key, getnstr, wgetnstr, mvgetnstr, mvwgetnstr, getstr, wgetstr, mvgetstr, mvwgetstr, keypad, is_keypad, notimeout, timeout, wtimeout, nodelay, ungetch, set_escdelay — curses input stream routines

LIBRARY

Curses Library (libcurses, -lcurses)

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
keyok(int key_symbol, bool flag); int
has_key(int key_symbol); int
define_key(char *sequence, int key_symbol); int
getnstr(char *str, int limit); int
wgetnstr(WINDOW *win, char *str, int limit); int
mvgetnstr(int y, int x, char *str, int limit); int
mvwgetnstr(WINDOW *win, int y, int x, char *str, int limit); int
getstr(char *str); int
wgetstr(WINDOW *win, char *str); int
mvgetstr(int y, int x, char *str); int
mvwgetstr(WINDOW *win, int y, int x, char *str); int
keypad(WINDOW *win, boolf flag); bool
is_keypad(const WINDOW *win); int
notimeout(WINDOW *win, boolf flag); int
timeout(int delay); int
wtimeout(WINDOW *win, int delay); int
nodelay(WINDOW *win, boolf flag); int
ungetch(int c); int
set_escdelay(int escdelay); extern int ESCDELAY;

DESCRIPTION

These functions read characters and strings from the window input file descriptor. The getch() function reads a character from the stdscr input file descriptor and returns it. If the keypad() flag has been set to TRUE, then getch() will assemble multi-character key sequences into key symbols, If the terminal is resized, getch() will return KEY_RESIZE, regardless of the setting of keypad(). Calling getch() will cause an implicit refresh() on stdscr. The wgetch() function is the same as the getch() function, excepting that it reads from the input file descriptor associated with the window specified by win. If the keypad() flag is TRUE then the assembly of specific key symbols can be disabled by using the keyok() function. If the flag is set to FALSE on a key symbol then getch() will behave as if the character sequence associated with that key symbol was not recognised and will return the component characters one at a time to the caller. The is_keypad() function returns TRUE if the keypad flag is set for the window specified by win. The has_key() function takes a key value and returns TRUE if the current terminal recognises a key with that value, otherwise FALSE. Custom associations between sequences of characters and a key symbol can be made by using the define_key() function. Normally, these associations are made by the information in the terminfo(5) database but the define_key() function gives the capability to remove or add more associations. If define_key() is passed a non-NULL string in sequence it will associate that sequence with the key symbol passed in key_symbol. The key symbol may be one of the ones listed below or a custom value that is application defined. It is valid to have multiple character sequences map to the same key symbol and there are no constraints on the length of the sequence allowed. The assembly of custom sequences follow the same rules for inter-character timing and so forth as the terminfo(5) derived ones. If define_key() is passed a NULL in sequence then all associations for the key symbol in key_symbol will be deleted, this includes any associations that were derived from terminfo(5). The mvgetch() and mvwgetch() functions are the same as the getch() and wgetch() functions, respectively, excepting that wmove() is called to move the cursor to the position specified by y, x before the character is read. Calling getnstr(), wgetnstr(), mvgetnstr() or mvwgetnstr() is effectively the same as calling getch() repeatedly until a newline is received or the character limit limit is reached. Once this happens the string is NULL terminated and returned in str. During input, the normal curses input key processing is performed and affects the input buffer. The mvgetnstr() function calls wmove() to move the cursor to the position given by y, x before getting the string, wgetnstr() reads the input from the designated window, mvwgetnstr() moves the cursor to the position given by y, x before getting the input from the designated window. The functions getstr(), wgetstr(), mvgetstr(), and mvwgetstr() are similar to getnstr(), wgetnstr(), mvgetnstr(), and mvwgetnstr(), respectively, excepting that there is no limit on the number of characters that may be inserted into str. This may cause the buffer to be overflowed, so their use is not recommended. The keypad() function is used to affect how getch() processes input characters. If flag is set to TRUE, then getch() will scan the input stream looking for multi-character key sequences that are emitted by some terminal function keys. If a recognised sequence of characters is found, then getch() will collapse that sequence into an integer key symbol, as shown below. The default setting for the flag is FALSE. The notimeout() function controls whether or not getch() will wait indefinitely between characters in a multi-character key sequence or not. If flag is TRUE, then there is no timeout applied between characters comprising a multi-character key sequence. If flag is FALSE, then the component characters of a multi-character sequence must not have an inter-character gap of more than ESCDELAY. If this timing is exceeded, then the multi-character key assembly is deemed to have failed and the characters read thus far are returned one at a time when getch() is called. The default setting for the flag is FALSE. The default value of ESCDELAY is 300ms. If ESCDELAY is negative, no timeout is applied between characters comprising a multi-character key sequence. The timeout() function affects the behaviour of getch() when reading a character from stdscr. If delay is negative, then getch() will block indefinitely on a read. If delay is 0, then getch() will return immediately with ERR if there are no characters immediately available. If delay is a positive number, then getch() will wait for that many milliseconds before returning and, if no character was available, then ERR will be returned. Note that for a positive number, the timeout is only accurate to the nearest tenth of a second. Also, the maximum value of delay is 25500 milliseconds. The wtimeout() function does the same as timeout() but applies to the specified window win. The nodelay() function turns on and off blocking reads for getch(). If flag is TRUE, then getch() will not block on reads, if flag is FALSE, then reads will block. The default setting for the flag is FALSE. nodelay(win, TRUE) is equivalent to wtimeout(win, 0) and nodelay(win, FALSE) is equivalent to wtimeout(win, -1). ungetch() will convert c into an unsigned char and push that character back onto the input stream. Only one character of push-back is guaranteed to work, more may be possible depending on system resources. The set_escdelay() function sets the ESCDELAY value of the current screen to escdelay.

RETURN VALUES

The functions getch(), wgetch(), mvgetch(), and mvwgetch() will return the value of the key pressed or ERR in the case of an error or a timeout. Additionally, if keypad(TRUE) has been called on a window, then it may return one of the following values:

Termcap entry	getch Return Value	Key Function
!1	KEY_SSAVE	Shift Save
!2	KEY_SSUSPEND	Shift Suspend
!3	KEY_SUNDO	Shift Undo
#1	KEY_SHELP	Shift Help
#2	KEY_SHOME	Shift Home
#3	KEY_SIC	Shift Insert Character
#4	KEY_SLEFT	Shift Left Arrow
%0	KEY_REDO	Redo
%1	KEY_HELP	Help
%2	KEY_MARK	Mark
%3	KEY_MESSAGE	Message
%4	KEY_MOVE	Move
%5	KEY_NEXT	Next Object
%6	KEY_OPEN	Open
%7	KEY_OPTIONS	Options
%8	KEY_PREVIOUS	Previous Object
%9	KEY_PRINT	Print
%a	KEY_SMESSAGE	Shift Message
%b	KEY_SMOVE	Shift Move
%c	KEY_SNEXT	Shift Next Object
%d	KEY_SOPTIONS	Shift Options
%e	KEY_SPREVIOUS	Shift Previous Object
%f	KEY_SPRINT	Shift Print
%g	KEY_SREDO	Shift Redo
%h	KEY_SREPLACE	Shift Replace
%i	KEY_SRIGHT	Shift Right Arrow
%j	KEY_SRSUME	Shift Resume
&0	KEY_SCANCEL	Shift Cancel
&1	KEY_REFERENCE	Reference
&2	KEY_REFRESH	Refresh
&3	KEY_REPLACE	Replace
&4	KEY_RESTART	Restart
&5	KEY_RESUME	Resume
&6	KEY_SAVE	Save
&7	KEY_SUSPEND	Suspend
&8	KEY_UNDO	Undo
&9	KEY_SBEG	Shift Begin
*0	KEY_SFIND	Shift Find
*1	KEY_SCOMMAND	Shift Command
*2	KEY_SCOPY	Shift Copy
*3	KEY_SCREATE	Shift Create
*4	KEY_SDC	Shift Delete Character
*5	KEY_SDL	Shift Delete Line
*6	KEY_SELECT	Select
*7	KEY_SEND	Shift End
*8	KEY_SEOL	Shift Clear to EOL
*9	KEY_SEXIT	Shift Exit
@0	KEY_FIND	Find
@1	KEY_BEG	Begin
@2	KEY_CANCEL	Cancel
@3	KEY_CLOSE	Close
@4	KEY_COMMAND	Command
@5	KEY_COPY	Copy
@6	KEY_CREATE	Create
@7	KEY_END	End
@8	KEY_ENTER	Enter
@9	KEY_EXIT	Exit
F1	KEY_F(11)	Function Key 11
F2	KEY_F(12)	Function Key 12
F3	KEY_F(13)	Function Key 13
F4	KEY_F(14)	Function Key 14
F5	KEY_F(15)	Function Key 15
F6	KEY_F(16)	Function Key 16
F7	KEY_F(17)	Function Key 17
F8	KEY_F(18)	Function Key 18
F9	KEY_F(19)	Function Key 19
FA	KEY_F(20)	Function Key 20
FB	KEY_F(21)	Function Key 21
FC	KEY_F(22)	Function Key 22
FD	KEY_F(23)	Function Key 23
FE	KEY_F(24)	Function Key 24
FF	KEY_F(25)	Function Key 25
FG	KEY_F(26)	Function Key 26
FH	KEY_F(27)	Function Key 27
FI	KEY_F(28)	Function Key 28
FJ	KEY_F(29)	Function Key 29
FK	KEY_F(30)	Function Key 30
FL	KEY_F(31)	Function Key 31
FM	KEY_F(32)	Function Key 32
FN	KEY_F(33)	Function Key 33
FO	KEY_F(34)	Function Key 34
FP	KEY_F(35)	Function Key 35
FQ	KEY_F(36)	Function Key 36
FR	KEY_F(37)	Function Key 37
FS	KEY_F(38)	Function Key 38
FT	KEY_F(39)	Function Key 39
FU	KEY_F(40)	Function Key 40
FV	KEY_F(41)	Function Key 41
FW	KEY_F(42)	Function Key 42
FX	KEY_F(43)	Function Key 43
FY	KEY_F(44)	Function Key 44
FZ	KEY_F(45)	Function Key 45
Fa	KEY_F(46)	Function Key 46
Fb	KEY_F(47)	Function Key 47
Fc	KEY_F(48)	Function Key 48
Fd	KEY_F(49)	Function Key 49
Fe	KEY_F(50)	Function Key 50
Ff	KEY_F(51)	Function Key 51
Fg	KEY_F(52)	Function Key 52
Fh	KEY_F(53)	Function Key 53
Fi	KEY_F(54)	Function Key 54
Fj	KEY_F(55)	Function Key 55
Fk	KEY_F(56)	Function Key 56
Fl	KEY_F(57)	Function Key 57
Fm	KEY_F(58)	Function Key 58
Fn	KEY_F(59)	Function Key 59
Fo	KEY_F(60)	Function Key 60
Fp	KEY_F(61)	Function Key 61
Fq	KEY_F(62)	Function Key 62
Fr	KEY_F(63)	Function Key 63
K1	KEY_A1	Upper left key in keypad
K2	KEY_B2	Centre key in keypad
K3	KEY_A3	Upper right key in keypad
K4	KEY_C1	Lower left key in keypad
K5	KEY_C3	Lower right key in keypad
Km	KEY_MOUSE	Mouse Event
k0	KEY_F0	Function Key 0
k1	KEY_F(1)	Function Key 1
k2	KEY_F(2)	Function Key 2
k3	KEY_F(3)	Function Key 3
k4	KEY_F(4)	Function Key 4
k5	KEY_F(5)	Function Key 5
k6	KEY_F(6)	Function Key 6
k7	KEY_F(7)	Function Key 7
k8	KEY_F(8)	Function Key 8
k9	KEY_F(9)	Function Key 9
k;	KEY_F(10)	Function Key 10
kA	KEY_IL	Insert Line
ka	KEY_CATAB	Clear All Tabs
kB	KEY_BTAB	Back Tab
kb	KEY_BACKSPACE	Backspace
kC	KEY_CLEAR	Clear
kD	KEY_DC	Delete Character
kd	KEY_DOWN	Down Arrow
kE	KEY_EOL	Clear to End Of Line
kF	KEY_SF	Scroll Forward one line
kH	KEY_LL	Home Down
kh	KEY_HOME	Home
kI	KEY_IC	Insert Character
kL	KEY_DL	Delete Line
kl	KEY_LEFT	Left Arrow
kM	KEY_EIC	Exit Insert Character Mode
kN	KEY_NPAGE	Next Page
kP	KEY_PPAGE	Previous Page
kR	KEY_SR	Scroll One Line Back
kr	KEY_RIGHT	Right Arrow
kS	KEY_EOS	Clear to End Of Screen
kT	KEY_STAB	Set Tab
kt	KEY_CTAB	Clear Tab
ku	KEY_UP	Up Arrow

Note that not all terminals are capable of generating all the keycodes listed above nor are terminfo entries normally configured with all the above capabilities defined. Other functions that return an int will return one of the following values:

OK

The function completed successfully.

ERR

An error occurred in the function.

Functions returning pointers will return NULL if an error is detected.

SEE ALSO

curses_cursor(3), curses_keyname(3), curses_refresh(3), curses_tty(3), terminfo(5)

STANDARDS

The NetBSD Curses library complies with the X/Open Curses specification, part of the Single Unix Specification.

NOTES

The keyok() and define_key() functions are implementations of extensions made by the NCurses library to the Curses standard. Portable implementations should avoid the use of these functions.

HISTORY

The Curses package appeared in 4.0BSD. The is_keypad() and set_tabsize() functions are ncurses extension to the Curses library and was added in NetBSD 8.0.