Provided by: ncurses-doc_6.4+20230625-2_all bug

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 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.

       The  getnstr  function reads from the stdscr default window.  The other functions, such as
       wgetnstr, read from the window given as a parameter.

       getnstr 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:

       •   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.

       •   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).

RETURN VALUE

       All routines return the integer ERR upon failure  and  an  OK  (SVr4  specifies  only  “an
       integer value other than ERR”) upon successful completion.

       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 interrupts 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.

NOTES

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

PORTABILITY

       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”, 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 do, some do not count it:

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

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

       •   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:

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

       •   Solaris xcurses limits the result to LINE_MAX bytes.

       •   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.

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

       •   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:

       •   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.

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

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

       Other implementations differ in their treatment of special characters:

       •   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.

       •   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.

       •   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

       ncurses(3NCURSES), getch(3NCURSES), termattrs(3NCURSES), curses_variables(3NCURSES).