# curs_refresh 3x

    curs_refresh(3x)                                              curs_refresh(3x)

## NAME

           doupdate, redrawwin, refresh, wnoutrefresh, wredrawln, wrefresh -
           refresh curses windows and lines

## SYNOPSIS

           #include <curses.h>

           int refresh(void);
           int wrefresh(WINDOW *win);
           int wnoutrefresh(WINDOW *win);
           int doupdate(void);
           int redrawwin(WINDOW *win);
           int wredrawln(WINDOW *win, int beg_line, int num_lines);

## DESCRIPTION

### refresh/wrefresh

           The refresh and wrefresh routines (or wnoutrefresh and  doupdate)  must
           be called to get actual output to the terminal, as other routines mere-
           ly manipulate data structures.  The routine wrefresh copies  the  named
           window  to  the  physical  screen,  taking into account what is already
           there to do optimizations.  The refresh routine is the same, using std-
           scr as the default window.  Unless leaveok has been enabled, the physi-
           cal cursor of the terminal is left at the location of  the  cursor  for
           that window.

### wnoutrefresh/doupdate

           The wnoutrefresh and doupdate routines allow multiple updates with more
           efficiency than wrefresh alone.  In addition to all the  window  struc-
           tures,  curses  keeps  two  data  structures  representing the terminal
           screen:

           o   a physical screen, describing what is actually on the screen, and

           o   a virtual screen, describing what the programmer wants to  have  on
               the screen.

           The routine wrefresh works by

           o   first  calling  wnoutrefresh,  which copies the named window to the
               virtual screen, and

           o   then calling doupdate, which compares the  virtual  screen  to  the
               physical screen and does the actual update.

           If the programmer wishes to output several windows at once, a series of
           calls to wrefresh results in  alternating  calls  to  wnoutrefresh  and
           doupdate,  causing  several  bursts  of output to the screen.  By first
           calling wnoutrefresh for each window, it is then possible to call doup-
           date  once,  resulting  in  only  one burst of output, with fewer total
           characters transmitted and less CPU time used.

           If the win argument to wrefresh is the physical screen (i.e., the glob-
           al  variable  curscr),  the screen is immediately cleared and repainted
           from scratch.

           The phrase "copies the named window to the virtual screen" above is am-
           biguous.   What actually happens is that all touched (changed) lines in
           the window are copied to the virtual  screen.   This  affects  programs
           that use overlapping windows; it means that if two windows overlap, you
           can refresh them in either order and the overlap region will  be  modi-
           fied  only  when  it  is  explicitly  changed.  (But see the section on
           PORTABILITY below for a warning about exploiting this behavior.)

### wredrawln/redrawwin

           The wredrawln routine indicates to curses that some  screen  lines  are
           corrupted  and  should  be  thrown away before anything is written over
           them.  It touches the indicated lines (marking them changed).  The rou-
           tine redrawwin touches the entire window.

## RETURN VALUE

           Routines  that  return an integer return ERR upon failure, and OK (SVr4
           only specifies "an integer value other than ERR") upon successful  com-
           pletion.

           X/Open does not define any error conditions.  In this implementation

              wnoutrefresh
                   returns  an error if the window pointer is null, or if the win-
                   dow is really a pad.

              wredrawln
                   returns an error if the associated call to touchln  returns  an
                   error.

## NOTES

           Note that refresh and redrawwin may be macros.

## PORTABILITY

           The XSI Curses standard, Issue 4 describes these functions.

           Whether  wnoutrefresh  copies to the virtual screen the entire contents
           of a window or just its changed portions has never been well-documented
           in  historic  curses  versions (including SVr4).  It might be unwise to
           rely on either behavior in programs that might have to be  linked  with
           other curses implementations.  Instead, you can do an explicit touchwin
           before the wnoutrefresh call to guarantee an entire-contents copy  any-
           where.

## SEE ALSO

           curses(3x), curs_outopts(3x) curs_variables(3x).

                                                                  curs_refresh(3x)