Miscellaneous Library Functions curs_clear(3X)
NAME
erase, werase, clear, wclear, clrtobot, wclrtobot, clrtoeol,
wclrtoeol - clear all or part of a curses window
SYNOPSIS
# include
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, butthey 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. RETURN VALUE All routines return the integer OK on success and ERR onfailure. 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, SunOS 5.10 Last change: 1Miscellaneous Library Functions curs_clear(3X)
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() andwclear(). That fact is not documented in other implementa-
tions, and may not be true of implementations which were not derived from SVr4 source. Not obvious from the description, most implementations clearthe screen after wclear even for a subwindow or derived win-
dow. If you do not want to clear the screen during the next wrefresh, use werase instead.SEE ALSO
curses(3X), curs_outopts(3X), curs_refresh(3X)
SunOS 5.10 Last change: 2