# 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

           The refresh and wrefresh  routines  (or  wnoutrefresh  and
           doupdate)  must be called to get actual output to the ter-
           minal, as other routines  merely  manipulate  data  struc-
           tures.   The  routine  wrefresh copies the named window to
           the physical terminal screen, taking into account what  is
           already there to do optimizations.  The refresh routine is
           the same, using stdscr  as  the  default  window.   Unless
           leaveok  has been enabled, the physical cursor of the ter-
           minal is left at the location of the cursor for that  win-
           dow.

           The  wnoutrefresh and doupdate routines allow multiple up-
           dates with more efficiency than wrefresh alone.  In  addi-
           tion  to  all the window structures, curses keeps two data
           structures representing the terminal  screen:  a  physical
           screen,  describing  what is actually on the screen, and a
           virtual screen, describing what the  programmer  wants  to
           have on the screen.

           The  routine wrefresh works by first calling wnoutrefresh,
           which copies the named window to the virtual  screen,  and
           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 se-
           ries of calls to wrefresh results in alternating calls  to
           wnoutrefresh  and doupdate, causing several bursts of out-
           put to the screen.  By first calling wnoutrefresh for each
           window, it is then possible to call doupdate once, result-
           ing in only one burst of output, with fewer total  charac-
           ters transmitted and less CPU time used.  If the win argu-
           ment to wrefresh is the global variable curscr, the screen
           is immediately cleared and repainted from scratch.

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

           The wredrawln routine indicates to curses that some screen
           lines are corrupted and should be thrown away before  any-
           thing  is  written  over  them.   It touches the indicated
           lines (marking them  changed).   The  routine  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 completion.

           X/Open  does not define any error conditions.  In this im-
           plementation

                  wnoutrefresh
                       returns an error  if  the  window  pointer  is
                       null, or if the window 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  func-
           tions.

           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  ex-
           plicit  touchwin() before the wnoutrefresh() call to guar-
           antee an entire-contents copy anywhere.

## SEE ALSO

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

                                                           curs_refresh(3x)