#include <graphics.h>
void fillpoly(int numpoints, int *polypoints);
 

fillpoly draws the outline of a polygon with numpoints points in the
current line style and color (just as drawpoly does), then fills the
polygon using the current fill pattern and fill color.
polypoints points to a sequence of (numpoints * 2) integers. Each pair of
integers gives the x- and y-coordinates of a point on the polygon.

/* fillpoly example */
 
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
 
int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   int i, maxx, maxy;
 
   /* our polygon array */
   int poly[8];
 
   /* 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 */
   }
 
   maxx = getmaxx();
   maxy = getmaxy();
 
   poly[0] = 20; /* first vertex */
   poly[1] = maxy / 2;
   poly[2] = maxx - 20;/* second vertex */
   poly[3] = 20;
   poly[4] = maxx - 50;/* third vertex */
   poly[5] = maxy - 20;
   poly[6] = maxx / 2; /* fourth, fillpoly automatically */
   poly[7] = maxy / 2; /* closes the polygon */
 
 
   /* loop through the fill patterns */
   for (i=EMPTY_FILL; i<USER_FILL; i++) {
/* set fill pattern */
setfillstyle(i, getmaxcolor());
 
/* draw a filled polygon */
fillpoly(4, poly);
getch();
   }
 
   /* clean up */
   closegraph();
   return 0;
}

drawpoly floodfill graphresult setfillstyle

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