curs_clear(3X)                   Library calls                  curs_clear(3X)

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

erase, werase

     The erase and werase routines copy blanks to every position in the
     window, clearing the screen.

     Blanks created by erasure have the current background rendition (as set
     by wbkgdset(3X)) merged into them.

clear, wclear

     The clear and wclear routines are like erase and werase, but they also
     call clearok(3X), so that the screen is cleared completely on the next
     call to wrefresh for that window and repainted from scratch.

clrtobot, wclrtobot

     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.

clrtoeol, wclrtoeol

     The clrtoeol and wclrtoeol routines erase the current line to the right
     of the cursor, inclusive, to the end of the current line.

RETURN VALUE

     All routines return the integer OK on success and ERR on failure.

     In this implementation,

     o   functions using a window pointer parameter return ERR if it is null

     o   wclrtoeol returns an error if the cursor position is about to wrap.

NOTES

     erase, werase, clear, wclear, clrtobot, and clrtoeol may be implemented
     as macros.

PORTABILITY

     X/Open Curses Issue 4 describes these functions.  It specifies no error
     conditions for them.

     SVr4 documentation says that these functions return OK "or a non-negative
     integer if immedok() is set", referring to the return value from
     wrefresh, which in SVr4 returns a count of characters written to the
     window if its immedok property is set; in ncurses, it does not.

     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

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

ncurses 6.6                       2025-01-18                    curs_clear(3X)