https://invisible-island.net/ncurses/man/
curs_clear(3x) Library calls curs_clear(3x)
erase, werase, clear, wclear, clrtobot, wclrtobot, clrtoeol, wclrtoeol
- clear all or part of a curses window
#include <curses.h>
int erase(void);
int werase(WINDOW *win);
int clear(void);
int wclear(WINDOW *win);
int clrtobot(void);
int wclrtobot(WINDOW *win);
int clrtoeol(void);
int wclrtoeol(WINDOW *win);
The erase and werase routines copy blanks to every position in the
window, clearing the screen.
Blanks created by erasure have the current background rendition (as set
by wbkgdset(3x)) merged into them.
The clear and wclear routines are like erase and werase, but they also
call clearok(3x), so that the screen is cleared completely on the next
call to wrefresh for that window and repainted from scratch.
The clrtobot and wclrtobot routines erase from the cursor to the end of
screen. That is, they erase all lines below the cursor in the window.
Also, the current line to the right of the cursor, inclusive, is
erased.
The clrtoeol and wclrtoeol routines erase the current line to the right
of the cursor, inclusive, to the end of the current line.
All routines return the integer OK on success and ERR on failure.
In this implementation,
o functions using a window pointer parameter return ERR if it is null
o wclrtoeol returns an error if the cursor position is about to wrap.
erase, werase, clear, wclear, clrtobot, and clrtoeol may be implemented
as macros.
X/Open Curses Issue 4 describes these functions. It specifies no error
conditions for them.
SVr4 documentation says that these functions return OK "or a non-
negative integer if immedok() is set", referring to the return value
from wrefresh, which in SVr4 returns a count of characters written to
the window if its immedok property is set; in ncurses, it does not.
Some historic curses implementations had, as an undocumented feature,
the ability to do the equivalent of clearok(..., 1) by saying
touchwin(stdscr) or clear(stdscr). This will not work under ncurses.
This implementation, and others such as Solaris, sets the current
position to 0,0 after erasing via werase and wclear. That fact is not
documented in other implementations, and may not be true of
implementations which were not derived from SVr4 source.
Not obvious from the description, most implementations clear the screen
after wclear even for a subwindow or derived window. If you do not
want to clear the screen during the next wrefresh, use werase instead.
curses(3x), curs_outopts(3x), curs_refresh(3x), curs_variables(3x)
ncurses 6.5 2025-01-18 curs_clear(3x)