curs_clear(3) UNIX Programmer's Manual curs_clear(3)
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 com-
pletely 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 rendi-
tion (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,
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curs_clear(3) UNIX Programmer's Manual curs_clear(3)
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 implementa-
tions, and may not be true of implementations which were not
derived from SVr4 source.
curses(3), curs_outopts(3), curs_refresh(3)
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