# curs_getstr 3x 2024-04-20 ncurses 6.4 Library calls

    curs_getstr(3x)                  Library calls                 curs_getstr(3x)

## NAME

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

## SYNOPSIS

           #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);

## DESCRIPTION

           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
               parameter.

           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.

## RETURN VALUE

           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
           ERR.

           Functions prefixed with "mv" first perform cursor movement and fail  if
           the position (y, x) is outside the window boundaries.

## NOTES

           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
           recommended.

## PORTABILITY

           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_
           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 count it, some do not:

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

           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
               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
               SUSv2.

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

           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
           buffer:

           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.

## SEE ALSO

           curs_get_wstr(3x) describes comparable functions of the ncurses library
           in its wide-character configuration (ncursesw).

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

    ncurses 6.4                       2024-04-20                   curs_getstr(3x)