curs_get_wstr(3) | Library calls | curs_get_wstr(3)

# 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 function wgetn_wstr is equivalent to a series of calls to wget_wch(3) until a newline or carriage return terminates the series:

- The terminating character is not included in the returned string.
- An end-of-file condition is represented by WEOF, as defined in <wchar.h>.
- In all instances, the end of the string is terminated by a null wchar_t.
- The function stores the result in the area pointed to by the wstr parameter.
- The function 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).

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

Any of these functions other than wgetn_wstr may be macros.

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. may be macros.

# RETURN VALUE

All of these functions return the integer OK upon successful completion. If unsuccessful, they return ERR.

X/Open defines no error conditions.

In this implementation, these functions return an error

- if the window pointer is null,
- if its timeout expires without having any data, or
- 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.

- For analogy with wgetnstr, ncurses 6.2 uses a limit (based on LINE_MAX).
- Some other implementations (such as Solaris xcurses) do the same, while others (PDCurses) do not allow this.
- NetBSD 7 curses imitates ncurses 6.1 in this regard, treating a -1 as an indefinite number of characters.

# SEE ALSO

Functions: curses(3), curs_get_wch(3), curs_getstr(3).

2023-08-05 | ncurses 6.4