clearviewport()         Erase the Current Viewport

 #include   <graphics.h>

 void far   clearviewport(void);

    clearviewport() clears the current viewport.  The current position
    (CP) is returned to home position (0,0).

    Returns:    Nothing.

   -------------------------------- Example ---------------------------------

    The following statements establish a viewport and draws two
    rectangles in the viewport. The viewport is cleared and one more
    rectangle is drawn in it.

           #include <graphics.h>
           #include <conio.h>

           main()
           {
               int gdriver = DETECT;
               int gmode;

               initgraph(&gdriver,&gmode,"");
               setviewport(0,0,400,200,1);
               rectangle(100,50,300,100);
               rectangle(200,25,400,75);
               getch();
               clearviewport();
               rectangle(300,50,400,100);
               getch();
               closegraph();
           }