curs_clear(3x) — Linux manual page


curs_clear(3X)                                            curs_clear(3X)

NAME         top

       erase, werase, clear, wclear, clrtobot, wclrtobot, clrtoeol,
       wclrtoeol - clear all or part of a curses window

SYNOPSIS         top

       #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         top

       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.

       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

       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.

RETURN VALUE         top

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

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

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

       •   wclrtoeol returns an error if the cursor position is about to

NOTES         top

       Note that erase, werase, clear, wclear, clrtobot, and clrtoeol
       may be macros.

PORTABILITY         top

       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.

       The SVr4.0 manual says that these functions could return "a non-
       negative integer if immedok(3X) 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         top

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

COLOPHON         top

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