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),
curses_variables(3NCURSES)