NAME
erase, werase, clear, wclear, clrtobot, wclrtobot, clrtoeol, wclrtoeol
- clear all or part of a curses window
SYNOPSIS
# 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);
DESCRIPTION
The erase and werase routines copy blanks to every position in the
window, clearing the screen.
The clear and wclear routines are like erase and werase, but they also
call clearok, 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.
Blanks created by erasure have the current background rendition (as set
by wbkgdset) merged into them.
RETURN VALUE
All routines return the integer OK on success and ERR on failure. The
SVr4.0 manual says "or a non-negative integer if immedok is set", but
this appears to be an error.
X/Open defines no error conditions. In this implementation, functions
using a window pointer parameter return an error if it is null.
NOTES
Note that erase, werase, clear, wclear, clrtobot, and clrtoeol may be
macros.
PORTABILITY
These functions are described in the XSI Curses standard, Issue 4. The
standard specifies that they return ERR on failure, but specifies no
error conditions.
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.
SEE ALSO
ncurses(3NCURSES), outopts(3NCURSES), refresh(3NCURSES)
clear(3NCURSES)