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curs_getstr 3x

curs_getstr(3x)                                                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 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:

       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 (typi-
       cally a left motion).


RETURN VALUE

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

       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.


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", 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,
           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  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
           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  ter-
           minating 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 mod-
           ify  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 func-
           tion- 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., allow-
           ing one to enter a ^C into the buffer.


SEE ALSO

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



                                                               curs_getstr(3x)