curs_get_wstr

Section: Miscellaneous Library Functions (3X)
Updated:
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NAME

get_wstr, getn_wstr, wget_wstr, wgetn_wstr, mvget_wstr, mvgetn_wstr, mvwget_wstr, mvwgetn_wstr - get an array of wide characters from a curses terminal keyboard

SYNOPSIS

#include <curses.h>

int get_wstr(wint_t *wstr);


int getn_wstr(wint_t *wstr, int n);


int wget_wstr(WINDOW *win, wint_t *wstr);


int wgetn_wstr(WINDOW *win, wint_t *wstr, int n);


int mvget_wstr(int y, int x, wint_t *wstr);


int mvgetn_wstr(int y, int x, wint_t *wstr, int n);


int mvwget_wstr(WINDOW *win, int y, int x, wint_t *wstr);


int mvwgetn_wstr(WINDOW *win, int y, int x, wint_t *wstr, int n);

DESCRIPTION

The effect of get_wstr is as though a series of calls to get_wch(3X) were made, until a newline, other end-of-line, or end-of-file condition is processed. An end-of-file condition is represented by WEOF, as defined in <wchar.h>. The newline and end-of-line conditions are represented by the \n wchar_t value. In all instances, the end of the string is terminated by a null wchar_t. The routine places resulting values in the area pointed to by wstr.

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).

The effect of wget_wstr is as though a series of calls to wget_wch were made.

The effect of mvget_wstr is as though a call to move and then a series of calls to get_wch were made.

The effect of mvwget_wstr is as though a call to wmove and then a series of calls to wget_wch were made.

The getn_wstr, mvgetn_wstr, mvwgetn_wstr, and wgetn_wstr functions are identical to the get_wstr, mvget_wstr, mvwget_wstr, and wget_wstr functions, respectively, except that the *n_* versions read at most n characters, letting the application prevent overflow of the input buffer.

NOTES

Using get_wstr, mvget_wstr, mvwget_wstr, or wget_wstr to read a line that overflows the array pointed to by wstr causes undefined results. The use of getn_wstr, mvgetn_wstr, mvwgetn_wstr, or wgetn_wstr, respectively, is recommended.

These functions cannot return KEY_ values because there is no way to distinguish a KEY_ value from a valid wchar_t value.

All of these routines except wgetn_wstr may be macros.

RETURN VALUE

All of these functions return OK upon successful completion. Otherwise, they return ERR.

Functions using a window parameter return an error if it is null.

wgetn_wstr: returns an error if the associated call to wget_wch failed.

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.

PORTABILITY

These functions are described in The Single Unix Specification, Version 2. No error conditions are defined. This implementation returns ERR if the window pointer is null, or if the lower-level wget_wch call returns an ERR. In the latter case, an ERR return without other data is treated as an end-of-file condition, and the returned array contains a WEOF followed by a null wchar_t.

X/Open curses documented these functions to pass an array of wchar_t in 1997, but that was an error because of this part of the description:

: The effect of get_wstr() is as though a series of calls to get_wch() were made, until a newline character, end-of-line character, or end-of-file character is processed.

The latter function get_wch() can return a negative value, while wchar_t is a unsigned type. All of the vendors implement this using wint_t, following the standard.

X/Open Curses, Issue 7 (2009) is unclear regarding whether the terminating null wchar_t value is counted in the length parameter n. X/Open Curses, Issue 7 revised the corresponding description of wgetnstr to address this issue. The unrevised description of wget_nwstr can be interpreted either way. This implementation counts the terminator in the length.

X/Open Curses does not specify what happens if the length n is negative.
.IP • 4 For analogy with wgetnstr, ncurses 6.2 uses a limit (based on LINE_MAX).
.IP • 4 Some other implementations (such as Solaris xcurses) do the same, while others (PDCurses) do not allow this.
.IP • 4 NetBSD 7 curses imitates ncurses 6.1 in this regard, treating a -1 as an indefinite number of characters.