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);
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.
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.
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:
.IP • 4 ncurses 6.1 and PDCurses do not count the NUL in the given limit, while
.IP • 4 Solaris SVr4 and NetBSD curses count the NUL as part of the limit.
.IP • 4 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:
.IP • 4 Solaris SVr4 curses and PDCurses limit the result to 255 bytes. Other Unix systems than Solaris are likely to use the same limit.
.IP • 4 Solaris xcurses limits the result to LINE_MAX bytes.
.IP • 4 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.