wgetnstr(3x) — Linux manual page


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 *, 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

       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

       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

       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,

       ·   Solaris SVr4 and NetBSD curses count the NUL as part of the

       ·   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:

       ·   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

       ·   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
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