***************************************************************************
Copyright 2018,2020 Thomas E. Dickey *
Copyright 1998-2010,2016 Free Software Foundation, Inc. *
*
Permission is hereby granted, free of charge, to any person obtaining a *
copy of this software and associated documentation files (the *
"Software"), to deal in the Software without restriction, including *
without limitation the rights to use, copy, modify, merge, publish, *
distribute, distribute with modifications, sublicense, and/or sell *
copies of the Software, and to permit persons to whom the Software is *
furnished to do so, subject to the following conditions: *
*
The above copyright notice and this permission notice shall be included *
in all copies or substantial portions of the Software. *
*
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
*
Except as contained in this notice, the name(s) of the above copyright *
holders shall not be used in advertising or otherwise to promote the *
sale, use or other dealings in this Software without prior written *
authorization. *
***************************************************************************

$Id: curs_clear.3x,v 1.17 2020/02/02 23:34:34 tom Exp $
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.

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.

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.

Note that erase, werase, clear, wclear, clrtobot, and clrtoeol may be macros. 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.

curses(3X), curs_outopts(3X), curs_refresh(3X), curs_variables(3X)