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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO | COLOPHON |
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curs_getstr(3X) curs_getstr(3X)
getstr, getnstr, wgetstr, wgetnstr, mvgetstr, mvgetnstr,
mvwgetstr, mvwgetnstr - accept character strings from curses
terminal keyboard
#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);
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).
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.
Note that getstr, mvgetstr, and mvwgetstr may be macros.
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.
curses(3X), curs_getch(3X), curs_variables(3X).
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have
a bug report for this manual page, send it to
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2020-12-18. (At
that time, the date of the most recent commit that was found in
the repository was 2020-12-13.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
curs_getstr(3X)
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