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);
18 int mvwgetstr(WINDOW *win, int y, int x, char *str);
19 int mvgetnstr(int y, int x, char *str, int n);
20 int mvwgetnstr(WINDOW *win, int y, int x, char *str, int n);
21
23 The function getstr is equivalent to a series of calls to getch, until
24 a newline or carriage return is received (the terminating character is
25 not included in the returned string). The resulting value is placed in
26 the area pointed to by the character pointer str, followed by a NUL.
27 wgetnstr reads at most n characters, thus preventing a possible over‐
29 flow of the input buffer. Any attempt to enter more characters (other
30 than the terminating newline or carriage return) causes a beep. Func‐
31 tion keys also cause a beep and are ignored. The getnstr function
32 reads from the stdscr default window.
33 The user's erase and kill characters are interpreted. If keypad mode
35 is on for the window, KEY_LEFT and KEY_BACKSPACE are both considered
36 equivalent to the user's kill character.
37 Characters input are echoed only if echo is currently on. In that
39 case, backspace is echoed as deletion of the previous character (typi‐
40 cally a left motion).
41
43 All routines return the integer ERR upon failure and an OK (SVr4 speci‐
44 fies only “an integer value other than ERR”) upon successful comple‐
45 tion.
46 X/Open defines no error conditions.
48 In this implementation, these functions return an error if the window
50 pointer is null, or if its timeout expires without having any data.
51 This implementation provides an extension as well. If a SIGWINCH in‐
53 terrupts the function, it will return KEY_RESIZE rather than OK or ERR.
54 Functions with a “mv” prefix first perform a cursor movement using
56 wmove, and return an error if the position is outside the window, or if
57 the window pointer is null.
58
60 Note that getstr, mvgetstr, and mvwgetstr may be macros.
61
63 These functions are described in the XSI Curses standard, Issue 4.
64 They read single-byte characters only. The standard does not define
65 any error conditions. This implementation returns ERR if the window
66 pointer is null, or if the lower-level wgetch(3X) call returns an ERR.
67 SVr3 and early SVr4 curses implementations did not reject function
69 keys; the SVr4.0 documentation claimed that “special keys” (such as
70 function keys, “home” key, “clear” key, etc.) are “interpreted”, with‐
71 out giving details. It lied. In fact, the “character” value appended
72 to the string by those implementations was predictable but not useful
73 (being, in fact, the low-order eight bits of the key's KEY_ value).
74 The functions getnstr, mvgetnstr, and mvwgetnstr were present but not
76 documented in SVr4.
77 X/Open Curses, Issue 5 (2007) stated that these functions “read at most
79 n bytes” but did not state whether the terminating NUL is counted in
80 that limit. X/Open Curses, Issue 7 (2009) changed that to say they
81 “read at most n-1 bytes” to allow for the terminating NUL. As of 2018,
82 some implementations do, some do not count it:
83 • ncurses 6.1 and PDCurses do not count the NUL in the given limit,
85 while
86 • Solaris SVr4 and NetBSD curses count the NUL as part of the limit.
88 • Solaris xcurses provides both: its wide-character wget_nstr re‐
90 serves a NUL, but its wgetnstr does not count the NUL consistently.
91 In SVr4 curses, a negative value of n tells wgetnstr to assume that the
93 caller's buffer is large enough to hold the result, i.e., to act like
94 wgetstr. X/Open Curses does not mention this (or anything related to
95 negative or zero values of n), however most implementations use the
96 feature, with different limits:
97 • Solaris SVr4 curses and PDCurses limit the result to 255 bytes.
99 Other Unix systems than Solaris are likely to use the same limit.
100 • Solaris xcurses limits the result to LINE_MAX bytes.
102 • NetBSD 7 assumes no particular limit for the result from wgetstr.
104 However, it limits the wgetnstr parameter n to ensure that it is
105 greater than zero.
106 A comment in NetBSD's source code states that this is specified in
108 SUSv2.
109 • ncurses (before 6.2) assumes no particular limit for the result
111 from wgetstr, and treats the n parameter of wgetnstr like SVr4
112 curses.
113 • ncurses 6.2 uses LINE_MAX, or a larger (system-dependent) value
115 which the sysconf function may provide. If neither LINE_MAX or
116 sysconf is available, ncurses uses the POSIX value for LINE_MAX (a
117 2048 byte limit). In either case, it reserves a byte for the ter‐
118 minating NUL.
119
121 curses(3X), curs_getch(3X), curs_variables(3X).
122 curs_getstr(3X)