curs_getstr 3x 2023-11-25 ncurses 6.4 Library calls

curs_getstr(3x)                  Library calls                 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 *win, int y, int x, char *str, int n);


       The function wgetnstr is equivalent to a series of calls to wgetch(3x),
       until a newline or carriage return terminates the series:

       o   The terminating character is not included in the returned string.

       o   In all instances, the end of the string is terminated by a NUL.

       o   The  function  stores  the result in the area pointed to by the str

       o   The function reads at most n characters, thus preventing a possible
           overflow of the input buffer.

           Any  attempt  to  enter more characters (other than the terminating
           newline or carriage return) causes a beep.

           Function keys also cause a beep and are ignored.

       The user's erase and kill characters are interpreted:

       o   The erase character (e.g., ^H) erases the character at the  end  of
           the buffer, moving the cursor to the left.

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

       o   The kill character (e.g., ^U) erases the entire buffer, leaving the
           cursor at the beginning of the buffer.

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

       The   getnstr,   mvgetnstr,  mvwgetnstr,  and  wgetnstr  functions  are
       identical to the getstr, mvgetstr, mvwgetstr,  and  wgetstr  functions,
       respectively,  except  that the *n* versions read at most n characters,
       letting the application prevent overflow of the input buffer.


       All  of  these  functions  return  the  integer  OK   upon   successful
       completion.  (SVr4 specifies only "an integer value other than ERR") If
       unsuccessful, they return ERR.

       X/Open defines no error conditions.

       In this implementation, these functions return an error

       o   if the window pointer is null,

       o   if its timeout expires without having any data, or

       o   if the associated call to wgetch failed.

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

       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.


       Any of these functions other than wgetnstr may be macros.

       Using getstr, mvgetstr, mvwgetstr, or  wgetstr  to  read  a  line  that
       overflows  the  array  pointed to by str causes undefined results.  The
       use of getnstr, mvgetnstr, mvwgetnstr, or  wgetnstr,  respectively,  is


       These functions are described in The Single Unix Specification, Version
       2.  No error conditions are defined.

       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",
       without 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_

       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 count it, some do not:

       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
           reserves  a  NUL,  but  its  wgetnstr  does  not  count   the   NUL

       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
           terminating NUL.

       Although  getnstr  is equivalent to a series of calls to getch, it also
       makes changes to the curses modes to allow simple editing of the  input

       o   getnstr  saves  the  current  value of the nl, echo, raw and cbreak
           modes, and sets nl, noecho, noraw, and cbreak.

           getnstr handles the echoing of characters, rather than  relying  on
           the caller to set an appropriate mode.

       o   It  also  obtains  the erase and kill characters from erasechar and
           killchar, respectively.

       o   On return, getnstr restores the modes to their previous values.

       Other implementations differ in their treatment of special characters:

       o   While they may set the echo  mode,  other  implementations  do  not
           modify  the  raw  mode,  They  may  take the cbreak mode set by the
           caller into account when deciding whether to handle echoing  within
           getnstr or as a side-effect of the getch calls.

       o   The original ncurses (as pcurses in 1986) set noraw and cbreak when
           accepting input for getnstr.  That  may  have  been  done  to  make
           function- and cursor-keys work; it is not necessary with ncurses.

           Since  1995, ncurses has provided signal handlers for INTR and QUIT
           (e.g., ^C or ^\).  With the noraw and cbreak  settings,  those  may
           catch  a  signal  and stop the program, where other implementations
           allow one to enter those characters in the buffer.

       o   Starting in 2021 (ncurses 6.3), getnstr sets raw, rather than noraw
           and   cbreak  for  better  compatibility  with  SVr4-curses,  e.g.,
           allowing one to enter a ^C into the buffer.


       curses(3x), curs_getch(3x), curs_termattrs(3x), curs_variables(3x)

ncurses 6.4                       2023-11-25                   curs_getstr(3x)