Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
curs_getstr(3X)						       curs_getstr(3X)

       getstr, getnstr,	wgetstr, wgetnstr, mvgetstr, mvgetnstr,	mvwgetstr,
       mvwgetnstr - accept character strings from curses terminal keyboard

       #include	<curses.h>

       int getstr(char *str);
       int getnstr(char	*str, int n);
       int wgetstr(WINDOW *win,	char *str);
       int wgetnstr(WINDOW *win, char *str, int	n);
       int mvgetstr(int	y, int x, char *str);
       int mvwgetstr(WINDOW *win, int y, int x,	char *str);
       int mvgetnstr(int y, int	x, char	*str, int n);
       int mvwgetnstr(WINDOW *,	int y, int x, char *str, int n);

       The function getstr is equivalent to a series of	calls to getch,	 until
       a  newline or carriage return is	received (the terminating character is
       not included in the returned string).  The resulting value is placed in
       the area	pointed	to by the character pointer str, followed by a NUL.

       wgetnstr	 reads	at most	n characters, thus preventing a	possible over-
       flow of the input buffer.  Any attempt to enter more characters	(other
       than  the terminating newline or	carriage return) causes	a beep.	 Func-
       tion keys also cause a beep and	are  ignored.	The  getnstr  function
       reads from the stdscr default window.

       The  user's  erase and kill characters are interpreted.	If keypad mode
       is on for the window, KEY_LEFT and KEY_BACKSPACE	 are  both  considered
       equivalent to the user's	kill character.

       Characters  input  are  echoed  only  if	echo is	currently on.  In that
       case, backspace is echoed as deletion of	the previous character	(typi-
       cally a left motion).

       All routines return the integer ERR upon	failure	and an OK (SVr4	speci-
       fies only "an integer value other than ERR")  upon  successful  comple-

       X/Open defines no error conditions.

       In  this	 implementation, these functions return	an error if the	window
       pointer is null,	or if its timeout expires without having any data.

       This implementation provides an extension as well.  If a	 SIGWINCH  in-
       terrupts	the function, it will return KEY_RESIZE	rather than OK or ERR.

       Functions  with	a  "mv"	 prefix	 first perform a cursor	movement using
       wmove, and return an error if the position is outside the window, or if
       the window pointer is null.

       Note that getstr, mvgetstr, and mvwgetstr may be	macros.

       These  functions	 are  described	 in  the XSI Curses standard, Issue 4.
       They read single-byte characters	only.  The standard  does  not	define
       any  error  conditions.	 This implementation returns ERR if the	window
       pointer is null,	or if the lower-level wgetch(3X) call returns an ERR.

       SVr3 and	early SVr4 curses  implementations  did	 not  reject  function
       keys;  the  SVr4.0  documentation  claimed that "special	keys" (such as
       function	keys, "home" key, "clear" key, etc.) are "interpreted",	 with-
       out  giving details.  It	lied.  In fact,	the "character"	value appended
       to the string by	those implementations was predictable but  not	useful
       (being, in fact,	the low-order eight bits of the	key's KEY_ value).

       The  functions  getnstr,	mvgetnstr, and mvwgetnstr were present but not
       documented in SVr4.

       X/Open Curses, Issue 5 (2007) stated that these functions "read at most
       n  bytes"  but  did not state whether the terminating NUL is counted in
       that limit.  X/Open Curses, Issue 7 (2009) changed  that	 to  say  they
       "read at	most n-1 bytes"	to allow for the terminating NUL.  As of 2018,
       some implementations do,	some do	not count it:

       o   ncurses 6.1 and PDCurses do not count the NUL in the	 given	limit,

       o   Solaris SVr4	and NetBSD curses count	the NUL	as part	of the limit.

       o   Solaris  xcurses  provides  both:  its wide-character wget_nstr re-
	   serves a NUL, but its wgetnstr does not count the NUL consistently.

       In SVr4 curses, a negative value	of n tells wgetnstr to assume that the
       caller's	 buffer	 is large enough to hold the result, i.e., to act like
       wgetstr.	 X/Open	Curses does not	mention	this (or anything  related  to
       negative	 or  zero  values  of n), however most implementations use the
       feature,	with different limits:

       o   Solaris SVr4	curses and PDCurses limit the  result  to  255	bytes.
	   Other Unix systems than Solaris are likely to use the same limit.

       o   Solaris xcurses limits the result to	LINE_MAX bytes.

       o   NetBSD  7  assumes no particular limit for the result from wgetstr.
	   However, it limits the wgetnstr parameter n to ensure  that	it  is
	   greater than	zero.

	   A  comment in NetBSD's source code states that this is specified in

       o   ncurses (before 6.2)	assumes	no particular  limit  for  the	result
	   from	 wgetstr,  and	treats	the  n parameter of wgetnstr like SVr4

       o   ncurses 6.2 uses LINE_MAX, or  a  larger  (system-dependent)	 value
	   which  the  sysconf	function  may provide.	If neither LINE_MAX or
	   sysconf is available, ncurses uses the POSIX	value for LINE_MAX  (a
	   2048	 byte limit).  In either case, it reserves a byte for the ter-
	   minating NUL.

       curses(3X), curs_getch(3X), curs_variables(3X).



Want to link to this manual page? Use this URL:

home | help