1curs_getstr(3X) curs_getstr(3X)
2
6 getstr, getnstr, wgetstr, wgetnstr, mvgetstr, mvgetnstr, mvwgetstr,
7 mvwgetnstr - accept character strings from curses terminal keyboard
8
10 #include <curses.h>
11 int getstr(char *str);
13 int getnstr(char *str, int n);
14 int wgetstr(WINDOW *win, char *str);
15 int wgetnstr(WINDOW *win, char *str, int n);
16 int mvgetstr(int y, int x, char *str);
17 int mvwgetstr(WINDOW *win, int y, int x, char *str);
18 int mvgetnstr(int y, int x, char *str, int n);
19 int mvwgetnstr(WINDOW *, int y, int x, char *str, int n);
20
22 The function getstr is equivalent to a series of calls to getch, until
23 a newline or carriage return is received (the terminating character is
24 not included in the returned string). The resulting value is placed in
25 the area pointed to by the character pointer str, followed by a NUL.
26 wgetnstr reads at most n characters, thus preventing a possible over‐
28 flow of the input buffer. Any attempt to enter more characters (other
29 than the terminating newline or carriage return) causes a beep. Func‐
30 tion keys also cause a beep and are ignored. The getnstr function
31 reads from the stdscr default window.
32 The user's erase and kill characters are interpreted. If keypad mode
34 is on for the window, KEY_LEFT and KEY_BACKSPACE are both considered
35 equivalent to the user's kill character.
36 Characters input are echoed only if echo is currently on. In that
38 case, backspace is echoed as deletion of the previous character (typi‐
39 cally a left motion).
40
42 All routines return the integer ERR upon failure and an OK (SVr4 speci‐
43 fies only “an integer value other than ERR”) upon successful comple‐
44 tion.
45 X/Open defines no error conditions.
47 In this implementation, these functions return an error if the window
49 pointer is null, or if its timeout expires without having any data.
50 This implementation provides an extension as well. If a SIGWINCH in‐
52 terrupts the function, it will return KEY_RESIZE rather than OK or ERR.
53 Functions with a “mv” prefix first perform a cursor movement using
55 wmove, and return an error if the position is outside the window, or if
56 the window pointer is null.
57
59 Note that getstr, mvgetstr, and mvwgetstr may be macros.
60
62 These functions are described in the XSI Curses standard, Issue 4.
63 They read single-byte characters only. The standard does not define
64 any error conditions. This implementation returns ERR if the window
65 pointer is null, or if the lower-level wgetch(3X) call returns an ERR.
66 SVr3 and early SVr4 curses implementations did not reject function
68 keys; the SVr4.0 documentation claimed that “special keys” (such as
69 function keys, “home” key, “clear” key, etc.) are “interpreted”, with‐
70 out giving details. It lied. In fact, the “character” value appended
71 to the string by those implementations was predictable but not useful
72 (being, in fact, the low-order eight bits of the key's KEY_ value).
73 The functions getnstr, mvgetnstr, and mvwgetnstr were present but not
75 documented in SVr4.
76 X/Open Curses, Issue 5 (2007) stated that these functions “read at most
78 n bytes” but did not state whether the terminating NUL is counted in
79 that limit. X/Open Curses, Issue 7 (2009) changed that to say they
80 “read at most n-1 bytes” to allow for the terminating NUL. As of 2018,
81 some implementations do, some do not count it:
82 · ncurses 6.1 and PDCurses do not count the NUL in the given limit,
84 while
85 · Solaris SVr4 and NetBSD curses count the NUL as part of the limit.
87 · Solaris xcurses provides both: its wide-character wget_nstr re‐
89 serves a NUL, but its wgetnstr does not count the NUL consistently.
90 In SVr4 curses, a negative value of n tells wgetnstr to assume that the
92 caller's buffer is large enough to hold the result, i.e., to act like
93 wgetstr. X/Open Curses does not mention this (or anything related to
94 negative or zero values of n), however most implementations use the
95 feature, with different limits:
96 · Solaris SVr4 curses and PDCurses limit the result to 255 bytes.
98 Other Unix systems than Solaris are likely to use the same limit.
99 · Solaris xcurses limits the result to LINE_MAX bytes.
101 · NetBSD 7 assumes no particular limit for the result from wgetstr.
103 However, it limits the wgetnstr parameter n to ensure that it is
104 greater than zero.
105 A comment in NetBSD's source code states that this is specified in
107 SUSv2.
108 · ncurses (before 6.2) assumes no particular limit for the result
110 from wgetstr, and treats the n parameter of wgetnstr like SVr4
111 curses.
112 · ncurses 6.2 uses LINE_MAX, or a larger (system-dependent) value
114 which the sysconf function may provide. If neither LINE_MAX or
115 sysconf is available, ncurses uses the POSIX value for LINE_MAX (a
116 2048 byte limit). In either case, it reserves a byte for the ter‐
117 minating NUL.
118
120 curses(3X), curs_getch(3X), curs_variables(3X).
121 curs_getstr(3X)