curs_getstr(3x) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO | COLOPHON

curs_getstr(3X)                                          curs_getstr(3X)

NAME         top

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

SYNOPSIS         top

       #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         top

       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
       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 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 (typically a left motion).

RETURN VALUE         top

       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         top

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

PORTABILITY         top

       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.

SEE ALSO         top

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

COLOPHON         top

       This page is part of the ncurses (new curses) project.
       Information about the project can be found at 
       ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩.  If you have
       a bug report for this manual page, send it to
       bug-ncurses-request@gnu.org.  This page was obtained from the
       project's upstream Git mirror of the CVS repository
       ⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2021-04-01.  (At
       that time, the date of the most recent commit that was found in
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                                                         curs_getstr(3X)