# curs_clear 3x 2024-01-05 ncurses 6.4 Library calls

    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.

           X/Open defines no error conditions.  In this implementation,

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

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

## 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 SVr4.0 manual says that these functions could  return  "or  a  non-
           negative  integer  if immedok is set", referring to the return-value of
           wrefresh.  In that implementation, wrefresh would return a count of the
           number of characters written to the terminal.

           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 6.4                       2024-01-05                    curs_clear(3x)