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<TITLE>curs_getch 3x</TITLE><link rev=made href="mailto:bug-ncurses@gnu.org">
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<H1>curs_getch 3x</H1>
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<PRE>
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</PRE>
<H2>NAME</H2><PRE>
<STRONG>getch</STRONG>, <STRONG>wgetch</STRONG>, <STRONG>mvgetch</STRONG>, <STRONG>mvwgetch</STRONG>, <STRONG>ungetch</STRONG>, <STRONG>has_key</STRONG> - get
(or push back) characters from <STRONG>curses</STRONG> terminal keyboard
</PRE>
<H2>SYNOPSIS</H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>int</STRONG> <STRONG>getch(void);</STRONG>
<STRONG>int</STRONG> <STRONG>wgetch(WINDOW</STRONG> <STRONG>*win);</STRONG>
<STRONG>int</STRONG> <STRONG>mvgetch(int</STRONG> <STRONG>y,</STRONG> <STRONG>int</STRONG> <STRONG>x);</STRONG>
<STRONG>int</STRONG> <STRONG>mvwgetch(WINDOW</STRONG> <STRONG>*win,</STRONG> <STRONG>int</STRONG> <STRONG>y,</STRONG> <STRONG>int</STRONG> <STRONG>x);</STRONG>
<STRONG>int</STRONG> <STRONG>ungetch(int</STRONG> <STRONG>ch);</STRONG>
<STRONG>int</STRONG> <STRONG>has_key(int</STRONG> <STRONG>ch);</STRONG>
</PRE>
<H2>DESCRIPTION</H2><PRE>
The <STRONG>getch</STRONG>, <STRONG>wgetch</STRONG>, <STRONG>mvgetch</STRONG> and <STRONG>mvwgetch</STRONG>, routines read a
character from the window. In no-delay mode, if no input
is waiting, the value <STRONG>ERR</STRONG> is returned. In delay mode, the
program waits until the system passes text through to the
program. Depending on the setting of <STRONG>cbreak</STRONG>, 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 <STRONG>noecho</STRONG> 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
<STRONG>delch</STRONG> had been called. If the character value is any
other <STRONG>KEY_</STRONG> define, the user is alerted with a <STRONG>beep</STRONG> 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 <STRONG>wrefresh</STRONG>, <STRONG>wrefresh</STRONG> will be
called before another character is read.
If <STRONG>keypad</STRONG> is <STRONG>TRUE</STRONG>, 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
<STRONG><curses.h></STRONG> as macros with values outside the range of
8-bit characters whose names begin with <STRONG>KEY_.</STRONG> 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), <STRONG>curses</STRONG> 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 <STRONG>ungetch</STRONG> routine places <EM>ch</EM> back onto the input queue to
be returned by the next call to <STRONG>wgetch</STRONG>. Note that there
is, in effect, just one input queue for all windows.
<STRONG>Function</STRONG> <STRONG>Keys</STRONG>
The following function keys, defined in <STRONG><curses.h></STRONG>, might
be returned by <STRONG>getch</STRONG> if <STRONG>keypad</STRONG> has been enabled. Note
that not all of these are necessarily supported on any
particular terminal.
<EM>Name</EM> <EM>Key</EM> <EM>name</EM>
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(<EM>n</EM>) For 0 <= <EM>n</EM> <= 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).
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
Keypad is arranged like this:
+-----+------+-------+
| <STRONG>A1</STRONG> | <STRONG>up</STRONG> | <STRONG>A3</STRONG> |
+-----+------+-------+
|<STRONG>left</STRONG> | <STRONG>B2</STRONG> | <STRONG>right</STRONG> |
+-----+------+-------+
| <STRONG>C1</STRONG> | <STRONG>down</STRONG> | <STRONG>C3</STRONG> |
+-----+------+-------+
The <STRONG>has_key</STRONG> 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.
</PRE>
<H2>RETURN VALUE</H2><PRE>
All routines return the integer <STRONG>ERR</STRONG> upon failure and an
integer value other than <STRONG>ERR</STRONG> (<STRONG>OK</STRONG> in the case of ungetch())
upon successful completion.
</PRE>
<H2>NOTES</H2><PRE>
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. <STRONG>Ncurses</STRONG> uses the terminfo definition. If it
says that KEY_ENTER is control/M, <STRONG>getch</STRONG>, will return
KEY_ENTER when you press control/M.
When using <STRONG>getch</STRONG>, <STRONG>wgetch</STRONG>, <STRONG>mvgetch</STRONG>, or <STRONG>mvwgetch</STRONG>, nocbreak
mode (<STRONG>nocbreak</STRONG>) and echo mode (<STRONG>echo</STRONG>) 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 <STRONG>getch</STRONG>, <STRONG>mvgetch</STRONG>, and <STRONG>mvwgetch</STRONG> 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 <STRONG>KEY_UP</STRONG>,
<STRONG>KEY_DOWN</STRONG>, <STRONG>KEY_LEFT</STRONG>, <STRONG>KEY_RIGHT</STRONG>, <STRONG>KEY_HOME</STRONG>, <STRONG>KEY_END</STRONG>,
<STRONG>KEY_NPAGE</STRONG>, <STRONG>KEY_PPAGE</STRONG>, and function keys 1 through 12. The
Ins key is usually mapped to <STRONG>KEY_IC</STRONG>.
</PRE>
<H2>PORTABILITY</H2><PRE>
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 <STRONG>ERR</STRONG> on failure,
but specifies no error conditions.
The echo behavior of these functions on input of <STRONG>KEY_</STRONG> or
backspace characters was not specified in the SVr4 docu-
mentation. This description is adopted from the XSI
Curses standard.
The behavior of <STRONG>getch</STRONG> 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
<STRONG><A HREF="read.2.html">read(2)</A></STRONG> 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 <STRONG>getch</STRONG>; (b) signal receipt interrupts <STRONG>getch</STRONG> and
causes it to return ERR with <STRONG>errno</STRONG> set to <STRONG>EINTR</STRONG>. Under
the <STRONG>ncurses</STRONG> implementation, handled signals never inter-
rupt <STRONG>getch</STRONG>.
The <STRONG>has_key</STRONG> function is unique to <STRONG>ncurses</STRONG>. We recommend
that any code using it be conditionalized on the
<STRONG>NCURSES_VERSION</STRONG> feature macro.
</PRE>
<H2>SEE ALSO</H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_inopts.3x.html">curs_inopts(3x)</A></STRONG>, <STRONG><A HREF="curs_mouse.3x.html">curs_mouse(3x)</A></STRONG>,
<STRONG><A HREF="curs_move.3x.html">curs_move(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>. <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG>.
</PRE>
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