#include <graphics.h>
void clearviewport(void);
 

clearviewport erases the viewport and moves the CP (current position) to
home (0,0), relative to the viewport.

/* clearviewport example */
 
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
 
#define CLIP_ON 1   /* activates clipping in viewport */
 
int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode, ht;
 
   /* initialize graphics and local variables */
   initgraph(&gdriver, &gmode, "");
 
   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk) {   /* an error occurred */
printf("Graphics error: %s\n", grapherrormsg(errorcode));
 
printf("Press any key to halt:");
getch();
exit(1);   /* terminate with an error code */
   }
 
   setcolor(getmaxcolor());
   ht = textheight("W");
 
   /* message in default full-screen viewport */
   outtextxy(0, 0, "* <-- (0, 0) in default viewport");
 
   /* create a smaller viewport */
   setviewport(50, 50, getmaxx()-50, getmaxy()-50, CLIP_ON);
 
   /* display some messages */
   outtextxy(0, 0, "* <-- (0, 0) in smaller viewport");
 
   outtextxy(0, 2*ht, "Press any key to clear viewport:");
 
   getch();   /* wait for a key */
   clearviewport();   /* clear the viewport */
   /* output another message */
   outtextxy(0, 0, "Press any key to quit:");
 
   /* clean up */
   getch();
   closegraph();
   return 0;
}

cleardevice getviewsettings setviewport

  no output of example at the moment
  do not hesitate and add it...