принимать символьные строки с клавиатуры терминала curses (accept character strings from curses terminal keyboard)
Имя (Name)
getstr, getnstr, wgetstr, wgetnstr, mvgetstr, mvgetnstr,
mvwgetstr, mvwgetnstr - accept character strings from curses
terminal keyboard
Синопсис (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);
Описание (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).
Возвращаемое значение (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.
Примечание (Note)
Note that getstr, mvgetstr, and mvwgetstr may be macros.
Портативность (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.
Смотри также (See also)
curses(3X), curs_getch(3X), curs_termattrs(3X),
curs_variables(3X).
