'\" t .\"*************************************************************************** .\" Copyright (c) 1998-2015,2016 Free Software Foundation, Inc. * .\" * .\" Permission is hereby granted, free of charge, to any person obtaining a * .\" copy of this software and associated documentation files (the * .\" "Software"), to deal in the Software without restriction, including * .\" without limitation the rights to use, copy, modify, merge, publish, * .\" distribute, distribute with modifications, sublicense, and/or sell * .\" copies of the Software, and to permit persons to whom the Software is * .\" furnished to do so, subject to the following conditions: * .\" * .\" The above copyright notice and this permission notice shall be included * .\" in all copies or substantial portions of the Software. * .\" * .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * .\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * .\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * .\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * .\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * .\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. * .\" * .\" Except as contained in this notice, the name(s) of the above copyright * .\" holders shall not be used in advertising or otherwise to promote the * .\" sale, use or other dealings in this Software without prior written * .\" authorization. * .\"*************************************************************************** .\" .\" $Id: curs_getch.3x,v 1.49 2016/10/15 16:44:01 tom Exp $ .TH getch 3NCURSES "" .na .hy 0 .de bP .IP \(bu 4 .. .SH NAME \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR, \fBmvwgetch\fR, \fBungetch\fR, \fBhas_key\fR \- get (or push back) characters from \fBcurses\fR terminal keyboard .ad .hy .SH SYNOPSIS \fB#include \fR .PP \fBint getch(void);\fR .br \fBint wgetch(WINDOW *\fP\fIwin);\fR .br \fBint mvgetch(int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fR .br \fBint mvwgetch(WINDOW *\fP\fIwin\fP\fB, int \fP\fIy\fP\fB, int \fP\fIx\fP\fB);\fR .br \fBint ungetch(int \fP\fIch\fP\fB);\fR .br \fBint has_key(int \fP\fIch\fP\fB);\fR .br .SH DESCRIPTION .SS Reading characters The \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR and \fBmvwgetch\fR, routines read a character from the window. In no-delay mode, if no input is waiting, the value \fBERR\fR is returned. In delay mode, the program waits until the system passes text through to the program. Depending on the setting of \fBcbreak\fR, 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. .PP If \fBecho\fR 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: .bP 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 \fBdelch\fR had been called. .bP If the character value is any other \fBKEY_\fR define, the user is alerted with a \fBbeep\fR call. .bP If the character is a carriage-return, and if \fBnl\fP is enabled, it is translated to a line-feed after echoing. .bP Otherwise the character is simply output to the screen. .PP If the window is not a pad, and it has been moved or modified since the last call to \fBwrefresh\fR, \fBwrefresh\fR will be called before another character is read. .SS Keypad mode .PP If \fBkeypad\fR is \fBTRUE\fR, and a function key is pressed, the token for that function key is returned instead of the raw characters: .bP The predefined function keys are listed in \fB\fR as macros with values outside the range of 8-bit characters. Their names begin with \fBKEY_\fR. .bP Other (user-defined) function keys which may be defined using \fBdefine_key\fP(3X) have no names, but also are expected to have values outside the range of 8-bit characters. .PP Thus, a variable intended to hold the return value of a function key must be of short size or larger. .PP When a character that could be the beginning of a function key is received (which, on modern terminals, means an escape character), \fBcurses\fR 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. .PP In \fBncurses\fP, the timer normally expires after the value in \fBESCDELAY\fP (see \fBcurs_variables\fP(3X)). If \fBnotimeout\fP is \fBTRUE\fP, the timer does not expire; it is an infinite (or very large) value. Because function keys usually begin with an escape character, the terminal may appear to hang in notimeout mode after pressing the escape key until another key is pressed. .SS Ungetting characters .PP The \fBungetch\fR routine places \fIch\fR back onto the input queue to be returned by the next call to \fBwgetch\fR. There is just one input queue for all windows. .PP .SS Predefined key-codes The following special keys are defined in \fB\fR. .bP Except for the special case \fBKEY_RESIZE\fP, it is necessary to enable \fBkeypad\fR for \fBgetch\fP to return these codes. .bP Not all of these are necessarily supported on any particular terminal. .bP The naming convention may seem obscure, with some apparent misspellings (such as "RSUME" for "resume"). The names correspond to the long terminfo capability names for the keys, and were defined long ago, in the 1980s. .PP .TS center tab(/) ; l l . \fIName\fR/\fIKey\fR \fIname\fR _ 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(\fIn\fR)/T{ For 0 \(<= \fIn\fR \(<= 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(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_MOUSE/Mouse event read 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_RESIZE/Screen resized 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 .TE .PP Keypad is arranged like this: .br .TS center allbox tab(/) ; c c c . \fBA1\fR/\fBup\fR/\fBA3\fR \fBleft\fR/\fBB2\fR/\fBright\fR \fBC1\fR/\fBdown\fR/\fBC3\fR .TE .sp A few of these predefined values do \fInot\fP correspond to a real key: .bP .B KEY_RESIZE is returned when the \fBSIGWINCH\fP signal has been detected (see \fBinitscr\fP(3X) and \fBresizeterm\fR(3NCURSES)). This code is returned whether or not \fBkeypad\fP has been enabled. .bP .B KEY_MOUSE is returned for mouse-events (see \fBmouse\fR(3NCURSES)). This code relies upon whether or not \fBkeypad\fP(3X) has been enabled, because (e.g., with \fIxterm\fP mouse prototocol) ncurses must read escape sequences, just like a function key. .SS Testing key-codes .PP The \fBhas_key\fR routine takes a key-code value from the above list, and returns \fBTRUE\fP or \fBFALSE\fP according to whether the current terminal type recognizes a key with that value. .PP The library also supports these extensions: .RS 3 .TP 5 .B define_key defines a key-code for a given string (see \fBdefine_key\fP(3X)). .TP 5 .B key_defined checks if there is a key-code defined for a given string (see \fBkey_defined\fP(3X)). .RE .PP .SH RETURN VALUE All routines return the integer \fBERR\fR upon failure and an integer value other than \fBERR\fR (\fBOK\fR in the case of \fBungetch\fP) upon successful completion. .RS 3 .TP 5 \fBungetch\fP returns ERR if there is no more room in the FIFO. .TP \fBwgetch\fP returns ERR if the window pointer is null, or if its timeout expires without having any data, or if the execution was interrupted by a signal (\fBerrno\fR will be set to \fBEINTR\fR). .RE .PP Functions with a "mv" prefix first perform a cursor movement using \fBwmove\fP, and return an error if the position is outside the window, or if the window pointer is null. .SH 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. .PP Some keys may be the same as commonly used control keys, e.g., \fBKEY_ENTER\fP versus control/M, \fBKEY_BACKSPACE\fP versus control/H. Some curses implementations may differ according to whether they treat these control keys specially (and ignore the terminfo), or use the terminfo definitions. \fBNcurses\fR uses the terminfo definition. If it says that \fBKEY_ENTER\fP is control/M, \fBgetch\fR will return \fBKEY_ENTER\fP when you press control/M. .PP Generally, \fBKEY_ENTER\fP denotes the character(s) sent by the \fIEnter\fP key on the numeric keypad: .bP the terminal description lists the most useful keys, .bP the \fIEnter\fP key on the regular keyboard is already handled by the standard ASCII characters for carriage-return and line-feed, .bP depending on whether \fBnl\fP or \fBnonl\fP was called, pressing "Enter" on the regular keyboard may return either a carriage-return or line-feed, and finally .bP "Enter or send" is the standard description for this key. .PP When using \fBgetch\fR, \fBwgetch\fR, \fBmvgetch\fR, or \fBmvwgetch\fR, nocbreak mode (\fBnocbreak\fR) and echo mode (\fBecho\fR) 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. .PP Note that \fBgetch\fR, \fBmvgetch\fR, and \fBmvwgetch\fR may be macros. .PP 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 \fBKEY_UP\fR, \fBKEY_DOWN\fR, \fBKEY_LEFT\fR, \fBKEY_RIGHT\fR, \fBKEY_HOME\fR, \fBKEY_END\fR, \fBKEY_NPAGE\fR, \fBKEY_PPAGE\fR, and function keys 1 through 12. The Ins key is usually mapped to \fBKEY_IC\fR. .SH 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 \fBERR\fR on failure, but specifies no error conditions. .PP The echo behavior of these functions on input of \fBKEY_\fR or backspace characters was not specified in the SVr4 documentation. This description is adopted from the XSI Curses standard. .PP The behavior of \fBgetch\fR 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 \fBread\fR(2) call in progress or not, and also (in some implementations) depending on whether an input timeout or non-blocking mode has been set. .PP \fBKEY_MOUSE\fP is mentioned in XSI Curses, along with a few related terminfo capabilities, but no higher-level functions use the feature. The implementation in ncurses is an extension. .PP \fBKEY_RESIZE\fP is an extension first implemented for ncurses. NetBSD curses later added this extension. .PP Programmers concerned about portability should be prepared for either of two cases: (a) signal receipt does not interrupt \fBgetch\fR; (b) signal receipt interrupts \fBgetch\fR and causes it to return ERR with \fBerrno\fR set to \fBEINTR\fR. .PP The \fBhas_key\fR function is unique to \fBncurses\fR. We recommend that any code using it be conditionalized on the \fBNCURSES_VERSION\fR feature macro. .SH SEE ALSO \fBncurses\fR(3NCURSES), \fBinopts\fR(3NCURSES), \fBoutopts\fR(3NCURSES), \fBmouse\fR(3NCURSES), \fBmove\fR(3NCURSES), \fBrefresh\fR(3NCURSES), \fBcurses_variables\fR(3NCURSES), \fBresizeterm\fR(3NCURSES). .PP Comparable functions in the wide-character (ncursesw) library are described in \fBget_wch\fR(3NCURSES).